def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
self._pwd_available = True
try:
import pwd
# silent unused import warning
pwd = pwd
except:
self._pwd_available = False
def test_remote_server_key(sftpserver):
'''test .remote_server_key property'''
with sftpserver.serve_content(VFS):
this_conn = conn(sftpserver)
this_conn['cnopts'].hostkeys = None # turn-off hostkey verification
with pysftp.Connection(**this_conn) as sftp:
rsk = sftp.remote_server_key
hks = HostKeys()
hks.add(hostname=sftpserver.host, keytype=rsk.get_name(), key=rsk)
hks.save('sftpserver.pub')
def load_host_keys(filename):
"""
Read a file of known SSH host keys, in the format used by openssh, and
return a compound dict of ``hostname -> keytype ->`` `PKey
<paramiko.pkey.PKey>`. The hostname may be an IP address or DNS name. The
keytype will be either ``"ssh-rsa"`` or ``"ssh-dss"``.
This type of file unfortunately doesn't exist on Windows, but on posix,
it will usually be stored in ``os.path.expanduser("~/.ssh/known_hosts")``.
Since 1.5.3, this is just a wrapper around `.HostKeys`.
:param str filename: name of the file to read host keys from
:return:
nested dict of `.PKey` objects, indexed by hostname and then keytype
"""
from paramiko.hostkeys import HostKeys
return HostKeys(filename)
def load_host_keys(filename):
"""
Read a file of known SSH host keys, in the format used by openssh, and
return a compound dict of C{hostname -> keytype ->} L{PKey <paramiko.pkey.PKey>}.
The hostname may be an IP address or DNS name. The keytype will be either
C{"ssh-rsa"} or C{"ssh-dss"}.
This type of file unfortunately doesn't exist on Windows, but on posix,
it will usually be stored in C{os.path.expanduser("~/.ssh/known_hosts")}.
Since 1.5.3, this is just a wrapper around L{HostKeys}.
@param filename: name of the file to read host keys from
@type filename: str
@return: dict of host keys, indexed by hostname and then keytype
@rtype: dict(hostname, dict(keytype, L{PKey <paramiko.pkey.PKey>}))
"""
from paramiko.hostkeys import HostKeys
return HostKeys(filename)
class SSHClient (ClosingContextManager):
"""
A high-level representation of a session with an SSH server. This class
wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
Instances of this class may be used as context managers.
.. versionadded:: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by `save_host_keys`.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If ``filename`` is left as ``None``, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
:param str filename: the filename to read, or ``None``
:raises IOError:
if a filename was provided and the file could not be read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked after keys loaded via `load_system_host_keys`,
but will be saved back by `save_host_keys` (so they can be modified).
The missing host key policy `.AutoAddPolicy` adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
:param str filename: the filename to read
:raises IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
`load_host_keys` (plus any added directly) will be saved -- not any
host keys loaded with `load_system_host_keys`.
:param str filename: the filename to save to
:raises IOError: if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self._host_keys_filename is not None:
self.load_host_keys(self._host_keys_filename)
with open(filename, 'w') as f:
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write('%s %s %s\n' %
(hostname, keytype, key.get_base64()))
def get_host_keys(self):
"""
Get the local `.HostKeys` object. This can be used to examine the
local host keys or change them.
:return: the local host keys as a `.HostKeys` object.
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is ``"paramiko.transport"``
but it can be set to anything you want.
:param str name: new channel name for logging
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local `.HostKeys` objects. The
default policy is to reject all unknown servers (using `.RejectPolicy`).
You may substitute `.AutoAddPolicy` or write your own policy class.
:param .MissingHostKeyPolicy policy:
the policy to use when receiving a host key from a
previously-unknown server
"""
self._policy = policy
def _families_and_addresses(self, hostname, port):
"""
Yield pairs of address families and addresses to try for connecting.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:returns: Yields an iterable of ``(family, address)`` tuples
"""
guess = True
addrinfos = socket.getaddrinfo(
hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
for (family, socktype, proto, canonname, sockaddr) in addrinfos:
if socktype == socket.SOCK_STREAM:
yield family, sockaddr
guess = False
# some OS like AIX don't indicate SOCK_STREAM support, so just guess. :(
# We only do this if we did not get a single result marked as socktype
# == SOCK_STREAM.
if guess:
for family, _, _, _, sockaddr in addrinfos:
yield family, sockaddr
def connect(
self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True,
compress=False,
sock=None,
gss_auth=False,
gss_kex=False,
gss_deleg_creds=True,
gss_host=None,
banner_timeout=None
):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see `load_system_host_keys`)
and any local host keys (`load_host_keys`). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see `set_missing_host_key_policy`). The default policy is
to reject the key and raise an `.SSHException`.
Authentication is attempted in the following order of priority:
- The ``pkey`` or ``key_filename`` passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in
``~/.ssh/``
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:param str username:
the username to authenticate as (defaults to the current local
username)
:param str password:
a password to use for authentication or for unlocking a private key
:param .PKey pkey: an optional private key to use for authentication
:param str key_filename:
the filename, or list of filenames, of optional private key(s) to
try for authentication
:param float timeout:
an optional timeout (in seconds) for the TCP connect
:param bool allow_agent:
set to False to disable connecting to the SSH agent
:param bool look_for_keys:
set to False to disable searching for discoverable private key
files in ``~/.ssh/``
:param bool compress: set to True to turn on compression
:param socket sock:
an open socket or socket-like object (such as a `.Channel`) to use
for communication to the target host
:param bool gss_auth:
``True`` if you want to use GSS-API authentication
:param bool gss_kex:
Perform GSS-API Key Exchange and user authentication
:param bool gss_deleg_creds: Delegate GSS-API client credentials or not
:param str gss_host:
The targets name in the kerberos database. default: hostname
:param float banner_timeout: an optional timeout (in seconds) to wait
for the SSH banner to be presented.
:raises BadHostKeyException: if the server's host key could not be
verified
:raises AuthenticationException: if authentication failed
:raises SSHException: if there was any other error connecting or
establishing an SSH session
:raises socket.error: if a socket error occurred while connecting
.. versionchanged:: 1.15
Added the ``banner_timeout``, ``gss_auth``, ``gss_kex``,
``gss_deleg_creds`` and ``gss_host`` arguments.
"""
if not sock:
errors = {}
# Try multiple possible address families (e.g. IPv4 vs IPv6)
to_try = list(self._families_and_addresses(hostname, port))
for af, addr in to_try:
try:
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
# Break out of the loop on success
break
except socket.error as e:
# Raise anything that isn't a straight up connection error
# (such as a resolution error)
if e.errno not in (ECONNREFUSED, EHOSTUNREACH):
raise
# Capture anything else so we know how the run looks once
# iteration is complete. Retain info about which attempt
# this was.
errors[addr] = e
# Make sure we explode usefully if no address family attempts
# succeeded. We've no way of knowing which error is the "right"
# one, so we construct a hybrid exception containing all the real
# ones, of a subclass that client code should still be watching for
# (socket.error)
if len(errors) == len(to_try):
raise NoValidConnectionsError(errors)
t = self._transport = Transport(
sock, gss_kex=gss_kex, gss_deleg_creds=gss_deleg_creds)
t.use_compression(compress=compress)
if gss_kex and gss_host is None:
t.set_gss_host(hostname)
elif gss_kex and gss_host is not None:
t.set_gss_host(gss_host)
else:
pass
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
if banner_timeout is not None:
t.banner_timeout = banner_timeout
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
# If GSS-API Key Exchange is performed we are not required to check the
# host key, because the host is authenticated via GSS-API / SSPI as
# well as our client.
if not self._transport.use_gss_kex:
our_server_key = self._system_host_keys.get(server_hostkey_name,
{}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(server_hostkey_name,
{}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall
# out
self._policy.missing_host_key(self, server_hostkey_name,
server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, string_types):
key_filenames = [key_filename]
else:
key_filenames = key_filename
if gss_host is None:
gss_host = hostname
self._auth(username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host)
def close(self):
"""
Close this SSHClient and its underlying `.Transport`.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent is not None:
self._agent.close()
self._agent = None
def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
"""
Execute a command on the SSH server. A new `.Channel` is opened and
the requested command is executed. The command's input and output
streams are returned as Python ``file``-like objects representing
stdin, stdout, and stderr.
:param str command: the command to execute
:param int bufsize:
interpreted the same way as by the built-in ``file()`` function in
Python
:param int timeout:
set command's channel timeout. See `Channel.settimeout`.settimeout
:return:
the stdin, stdout, and stderr of the executing command, as a
3-tuple
:raises SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session(timeout=timeout)
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('r', bufsize)
stderr = chan.makefile_stderr('r', bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term='vt100', width=80, height=24, width_pixels=0,
height_pixels=0):
"""
Start an interactive shell session on the SSH server. A new `.Channel`
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
:param str term:
the terminal type to emulate (for example, ``"vt100"``)
:param int width: the width (in characters) of the terminal window
:param int height: the height (in characters) of the terminal window
:param int width_pixels: the width (in pixels) of the terminal window
:param int height_pixels: the height (in pixels) of the terminal window
:return: a new `.Channel` connected to the remote shell
:raises SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
:return: a new `.SFTPClient` session object
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying `.Transport` object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
:return: the `.Transport` for this connection
"""
return self._transport
def _auth(self, username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in ~/.ssh/
(if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = set()
two_factor_types = set(['keyboard-interactive', 'password'])
algo_map = {'DSA': {'class': DSSKey,
'filename': 'id_dsa'},
'EC': {'class': ECDSAKey,
'filename': 'id_ecds'},
'RSA': {'class': RSAKey,
'filename': 'id_rsa'}
}
# If GSS-API support and GSS-PI Key Exchange was performed, we attempt
# authentication with gssapi-keyex.
if gss_kex and self._transport.gss_kex_used:
try:
self._transport.auth_gssapi_keyex(username)
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
saved_exception = e
except Exception as e:
self._log(EXCEPTION, 'non-ssh exception')
raise
else:
return
# Try GSS-API authentication (gssapi-with-mic) only if GSS-API Key
# Exchange is not performed, because if we use GSS-API for the key
# exchange, there is already a fully established GSS-API context, so
# why should we do that again?
if gss_auth:
try:
self._transport.auth_gssapi_with_mic(username, gss_host,
gss_deleg_creds)
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
saved_exception = e
except Exception as e:
self._log(EXCEPTION, 'non-ssh exception')
raise
else:
return
if pkey is not None:
try:
self._log(DEBUG, 'Trying SSH key %s' %
hexlify(pkey.get_fingerprint()))
allowed_types = set(
self._transport.auth_publickey(username, pkey))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
saved_exception = e
except Exception as e:
self._log(EXCEPTION, 'non-ssh exception')
raise
if not two_factor:
for key_filename in key_filenames:
algo_opt = []
with open(key_filename, 'r') as f:
first_line = f.readline()
match = re.search('BEGIN (\S+) PRIVATE KEY', first_line)
algo = match.group(1)
if algo == 'OPENSSH':
estr = 'ED25519Key class not yet implemented'
self._log(EXCEPTION, estr)
raise SSHException(estr)
elif algo in algo_map:
algo_opt.append(algo)
elif algo not in algo_map:
self._log(DEBUG,
'First line of SSH key is:\n%s' % first_line)
self._log(DEBUG, 'Public Key Algorithm not recognized')
algo_opt.append(algo_map.keys())
for algo in algo_opt:
pk_class = algo_map[algo]['class']
try:
key = pk_class.from_private_key_file(
key_filename, password)
except SSHException as e:
self._log(DEBUG,
'%s is not the right Public Key Algorithm for file %s' % (
algo, key_filename_))
continue
except:
self._log(EXCEPTION, 'non-ssh exception')
raise
else:
self._log(DEBUG,
'%s is the right Public Key Algorithm for file %s' % (
algo, key_filename))
self._log(DEBUG, 'Trying key %s from %s' %
(hexlify(key.get_fingerprint()), key_filename))
try:
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
self._log(EXCEPTION, 'ssh exception')
raise
except:
self._log(EXCEPTION, 'non-ssh exception')
raise
else:
break
if not two_factor and allow_agent:
if self._agent is None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(DEBUG, 'Trying SSH agent key %s' %
hexlify(key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key password will
# return an allowed 2fac auth method
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
self._log(DEBUG,
'%s is not the right Public Key' % key)
except:
self._log(EXCEPTION, 'non-ssh exception')
raise
else:
self._log(DEBUG,
'%s is the right Public Key' % key)
break
if not two_factor:
keyfiles = []
if look_for_keys:
for pfx in ('~/.ssh', '~/ssh'):
for algo, adict in algo_map:
keyfile = os.path.join(os.path.expanduser(pfx),
adict['filename'])
if os.path.isfile(keyfile):
keyfiles.append((algo, keyfile))
for algo, filename in keyfiles:
pkey_class = algo_map[algo]['class']
try:
key = pkey_class.from_private_key_file(filename, password)
except SSHException as e:
self._log(
DEBUG, 'password does not match file %s' % filename)
continue
except Exception as e:
raise
else:
self._log(DEBUG, 'password matches file %s' % filename)
self._log(DEBUG, 'Trying discovered key %s in %s' %
(hexlify(key.get_fingerprint()), filename))
try:
# for 2-factor auth a successfully auth'd key will result
# in ['password']
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except Exception as e:
raise
else:
break
if password is not None:
try:
self._transport.auth_password(username, password)
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
saved_exception = e
else:
return
elif two_factor:
try:
self._transport.auth_interactive_dumb(username)
except AuthenticationException as e:
self._log(EXCEPTION, 'Authentication failure')
raise
except SSHException as e:
saved_exception = e
else:
return
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException('No authentication methods available')
def _log(self, level, msg):
self._transport._log(level, msg)
class SSHClient(ClosingContextManager):
"""
A high-level representation of a session with an SSH server. This class
wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
Instances of this class may be used as context managers.
.. versionadded:: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by `save_host_keys`.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If ``filename`` is left as ``None``, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
:param str filename: the filename to read, or ``None``
:raises IOError:
if a filename was provided and the file could not be read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked after keys loaded via `load_system_host_keys`,
but will be saved back by `save_host_keys` (so they can be modified).
The missing host key policy `.AutoAddPolicy` adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
:param str filename: the filename to read
:raises IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
`load_host_keys` (plus any added directly) will be saved -- not any
host keys loaded with `load_system_host_keys`.
:param str filename: the filename to save to
:raises IOError: if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self._host_keys_filename is not None:
self.load_host_keys(self._host_keys_filename)
with open(filename, 'w') as f:
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write('%s %s %s\n' %
(hostname, keytype, key.get_base64()))
def get_host_keys(self):
"""
Get the local `.HostKeys` object. This can be used to examine the
local host keys or change them.
:return: the local host keys as a `.HostKeys` object.
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is ``"paramiko.transport"``
but it can be set to anything you want.
:param str name: new channel name for logging
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local `.HostKeys` objects. The
default policy is to reject all unknown servers (using `.RejectPolicy`).
You may substitute `.AutoAddPolicy` or write your own policy class.
:param .MissingHostKeyPolicy policy:
the policy to use when receiving a host key from a
previously-unknown server
"""
self._policy = policy
def connect(self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True,
compress=False,
sock=None,
gss_auth=False,
gss_kex=False,
gss_deleg_creds=True,
gss_host=None,
banner_timeout=None):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see `load_system_host_keys`)
and any local host keys (`load_host_keys`). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see `set_missing_host_key_policy`). The default policy is
to reject the key and raise an `.SSHException`.
Authentication is attempted in the following order of priority:
- The ``pkey`` or ``key_filename`` passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in
``~/.ssh/``
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:param str username:
the username to authenticate as (defaults to the current local
username)
:param str password:
a password to use for authentication or for unlocking a private key
:param .PKey pkey: an optional private key to use for authentication
:param str key_filename:
the filename, or list of filenames, of optional private key(s) to
try for authentication
:param float timeout: an optional timeout (in seconds) for the TCP connect
:param bool allow_agent: set to False to disable connecting to the SSH agent
:param bool look_for_keys:
set to False to disable searching for discoverable private key
files in ``~/.ssh/``
:param bool compress: set to True to turn on compression
:param socket sock:
an open socket or socket-like object (such as a `.Channel`) to use
for communication to the target host
:param bool gss_auth: ``True`` if you want to use GSS-API authentication
:param bool gss_kex: Perform GSS-API Key Exchange and user authentication
:param bool gss_deleg_creds: Delegate GSS-API client credentials or not
:param str gss_host: The targets name in the kerberos database. default: hostname
:param float banner_timeout: an optional timeout (in seconds) to wait
for the SSH banner to be presented.
:raises BadHostKeyException: if the server's host key could not be
verified
:raises AuthenticationException: if authentication failed
:raises SSHException: if there was any other error connecting or
establishing an SSH session
:raises socket.error: if a socket error occurred while connecting
.. versionchanged:: 1.15
Added the ``banner_timeout``, ``gss_auth``, ``gss_kex``,
``gss_deleg_creds`` and ``gss_host`` arguments.
"""
if not sock:
for (family, socktype, proto, canonname,
sockaddr) in socket.getaddrinfo(hostname, port,
socket.AF_UNSPEC,
socket.SOCK_STREAM):
if socktype == socket.SOCK_STREAM:
af = family
addr = sockaddr
break
else:
# some OS like AIX don't indicate SOCK_STREAM support, so just guess. :(
af, _, _, _, addr = socket.getaddrinfo(hostname, port,
socket.AF_UNSPEC,
socket.SOCK_STREAM)
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
t = self._transport = Transport(sock,
gss_kex=gss_kex,
gss_deleg_creds=gss_deleg_creds)
t.use_compression(compress=compress)
if gss_kex and gss_host is None:
t.set_gss_host(hostname)
elif gss_kex and gss_host is not None:
t.set_gss_host(gss_host)
else:
pass
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
if banner_timeout is not None:
t.banner_timeout = banner_timeout
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
# If GSS-API Key Exchange is performed we are not required to check the
# host key, because the host is authenticated via GSS-API / SSPI as
# well as our client.
if not self._transport.use_gss_kex:
our_server_key = self._system_host_keys.get(
server_hostkey_name, {}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(server_hostkey_name,
{}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall out
self._policy.missing_host_key(self, server_hostkey_name,
server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, string_types):
key_filenames = [key_filename]
else:
key_filenames = key_filename
if gss_host is None:
gss_host = hostname
self._auth(username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host)
def close(self):
"""
Close this SSHClient and its underlying `.Transport`.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent is not None:
self._agent.close()
self._agent = None
def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
"""
Execute a command on the SSH server. A new `.Channel` is opened and
the requested command is executed. The command's input and output
streams are returned as Python ``file``-like objects representing
stdin, stdout, and stderr.
:param str command: the command to execute
:param int bufsize:
interpreted the same way as by the built-in ``file()`` function in
Python
:param int timeout:
set command's channel timeout. See `Channel.settimeout`.settimeout
:return:
the stdin, stdout, and stderr of the executing command, as a
3-tuple
:raises SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session()
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('r', bufsize)
stderr = chan.makefile_stderr('r', bufsize)
return stdin, stdout, stderr
def invoke_shell(self,
term='vt100',
width=80,
height=24,
width_pixels=0,
height_pixels=0):
"""
Start an interactive shell session on the SSH server. A new `.Channel`
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
:param str term:
the terminal type to emulate (for example, ``"vt100"``)
:param int width: the width (in characters) of the terminal window
:param int height: the height (in characters) of the terminal window
:param int width_pixels: the width (in pixels) of the terminal window
:param int height_pixels: the height (in pixels) of the terminal window
:return: a new `.Channel` connected to the remote shell
:raises SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
:return: a new `.SFTPClient` session object
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying `.Transport` object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
:return: the `.Transport` for this connection
"""
return self._transport
def _auth(self, username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in ~/.ssh/
(if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = []
# If GSS-API support and GSS-PI Key Exchange was performed, we attempt
# authentication with gssapi-keyex.
if gss_kex and self._transport.gss_kex_used:
try:
self._transport.auth_gssapi_keyex(username)
return
except Exception as e:
saved_exception = e
# Try GSS-API authentication (gssapi-with-mic) only if GSS-API Key
# Exchange is not performed, because if we use GSS-API for the key
# exchange, there is already a fully established GSS-API context, so
# why should we do that again?
if gss_auth:
try:
self._transport.auth_gssapi_with_mic(username, gss_host,
gss_deleg_creds)
return
except Exception as e:
saved_exception = e
if pkey is not None:
try:
self._log(
DEBUG,
'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
allowed_types = self._transport.auth_publickey(username, pkey)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
except SSHException as e:
saved_exception = e
if not two_factor:
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey, ECDSAKey):
try:
key = pkey_class.from_private_key_file(
key_filename, password)
self._log(
DEBUG, 'Trying key %s from %s' %
(hexlify(key.get_fingerprint()), key_filename))
self._transport.auth_publickey(username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor and allow_agent:
if self._agent is None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(
DEBUG, 'Trying SSH agent key %s' %
hexlify(key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(
username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor:
keyfiles = []
rsa_key = os.path.expanduser('~/.ssh/id_rsa')
dsa_key = os.path.expanduser('~/.ssh/id_dsa')
ecdsa_key = os.path.expanduser('~/.ssh/id_ecdsa')
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
if os.path.isfile(ecdsa_key):
keyfiles.append((ECDSAKey, ecdsa_key))
# look in ~/ssh/ for windows users:
rsa_key = os.path.expanduser('~/ssh/id_rsa')
dsa_key = os.path.expanduser('~/ssh/id_dsa')
ecdsa_key = os.path.expanduser('~/ssh/id_ecdsa')
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
if os.path.isfile(ecdsa_key):
keyfiles.append((ECDSAKey, ecdsa_key))
if not look_for_keys:
keyfiles = []
for pkey_class, filename in keyfiles:
try:
key = pkey_class.from_private_key_file(filename, password)
self._log(
DEBUG, 'Trying discovered key %s in %s' %
(hexlify(key.get_fingerprint()), filename))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(
username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except (SSHException, IOError) as e:
saved_exception = e
if password is not None:
try:
self._transport.auth_password(username, password)
return
except SSHException as e:
saved_exception = e
elif two_factor:
raise SSHException('Two-factor authentication requires a password')
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException('No authentication methods available')
def _log(self, level, msg):
self._transport._log(level, msg)
def do_ssh_paramiko_connect_to(transport, host, username, password, host_config=None, keyfiles=None, paramiko_config=None):
from paramiko import SSHException, PasswordRequiredException
from paramiko.agent import Agent
from paramiko.hostkeys import HostKeys
log("do_ssh_paramiko_connect_to%s", (transport, host, username, password, host_config, keyfiles, paramiko_config))
log("SSH transport %s", transport)
def configvalue(key):
#if the paramiko config has a setting, honour it:
if paramiko_config and key in paramiko_config:
return paramiko_config.get(key)
#fallback to the value from the host config:
return (host_config or {}).get(key)
def configbool(key, default_value=True):
return parse_bool(key, configvalue(key), default_value)
def configint(key, default_value=0):
v = configvalue(key)
if v is None:
return default_value
return int(v)
host_key = transport.get_remote_server_key()
assert host_key, "no remote server key"
log("remote_server_key=%s", keymd5(host_key))
if configbool("verify-hostkey", VERIFY_HOSTKEY):
host_keys = HostKeys()
host_keys_filename = None
KNOWN_HOSTS = get_ssh_known_hosts_files()
for known_hosts in KNOWN_HOSTS:
host_keys.clear()
try:
path = os.path.expanduser(known_hosts)
if os.path.exists(path):
host_keys.load(path)
log("HostKeys.load(%s) successful", path)
host_keys_filename = path
break
except IOError:
log("HostKeys.load(%s)", known_hosts, exc_info=True)
log("host keys=%s", host_keys)
keys = host_keys.lookup(host)
known_host_key = (keys or {}).get(host_key.get_name())
def keyname():
return host_key.get_name().replace("ssh-", "")
if host_key==known_host_key:
assert host_key
log("%s host key '%s' OK for host '%s'", keyname(), keymd5(host_key), host)
else:
dnscheck = ""
if configbool("verifyhostkeydns"):
try:
from xpra.net.sshfp import check_host_key
dnscheck = check_host_key(host, host_key)
except ImportError as e:
log("verifyhostkeydns failed", exc_info=True)
log.warn("Warning: cannot check SSHFP DNS records")
log.warn(" %s", e)
log("dnscheck=%s", dnscheck)
def adddnscheckinfo(q):
if dnscheck is not True:
if dnscheck:
q += [
"SSHFP validation failed:",
dnscheck
]
else:
q += [
"SSHFP validation failed"
]
if dnscheck is True:
#DNSSEC provided a matching record
log.info("found a valid SSHFP record for host %s", host)
elif known_host_key:
log.warn("Warning: SSH server key mismatch")
qinfo = [
"WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!",
"IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!",
"Someone could be eavesdropping on you right now (man-in-the-middle attack)!",
"It is also possible that a host key has just been changed.",
"The fingerprint for the %s key sent by the remote host is" % keyname(),
keymd5(host_key),
]
adddnscheckinfo(qinfo)
if configbool("stricthostkeychecking", VERIFY_STRICT):
log.warn("Host key verification failed.")
#TODO: show alert with no option to accept key
qinfo += [
"Please contact your system administrator.",
"Add correct host key in %s to get rid of this message.",
"Offending %s key in %s" % (keyname(), host_keys_filename),
"ECDSA host key for %s has changed and you have requested strict checking." % keyname(),
]
sys.stderr.write(os.linesep.join(qinfo))
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "SSH Host key has changed")
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "SSH Host key has changed")
else:
assert (not keys) or (host_key.get_name() not in keys)
if not keys:
log.warn("Warning: unknown SSH host")
else:
log.warn("Warning: unknown %s SSH host key", keyname())
qinfo = [
"The authenticity of host '%s' can't be established." % (host,),
"%s key fingerprint is" % keyname(),
keymd5(host_key),
]
adddnscheckinfo(qinfo)
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "Unknown SSH host '%s'" % host)
if configbool("addkey", ADD_KEY):
try:
if not host_keys_filename:
#the first one is the default,
#ie: ~/.ssh/known_hosts on posix
host_keys_filename = os.path.expanduser(KNOWN_HOSTS[0])
log("adding %s key for host '%s' to '%s'", keyname(), host, host_keys_filename)
if not os.path.exists(host_keys_filename):
keys_dir = os.path.dirname(host_keys_filename)
if not os.path.exists(keys_dir):
log("creating keys directory '%s'", keys_dir)
os.mkdir(keys_dir, 0o700)
elif not os.path.isdir(keys_dir):
log.warn("Warning: '%s' is not a directory")
log.warn(" key not saved")
if os.path.exists(keys_dir) and os.path.isdir(keys_dir):
log("creating known host file '%s'", host_keys_filename)
with umask_context(0o133):
with open(host_keys_filename, 'a+'):
pass
host_keys.add(host, host_key.get_name(), host_key)
host_keys.save(host_keys_filename)
except OSError as e:
log("failed to add key to '%s'", host_keys_filename)
log.error("Error adding key to '%s'", host_keys_filename)
log.error(" %s", e)
except Exception as e:
log.error("cannot add key", exc_info=True)
else:
log("ssh host key verification skipped")
def auth_agent():
agent = Agent()
agent_keys = agent.get_keys()
log("agent keys: %s", agent_keys)
if agent_keys:
for agent_key in agent_keys:
log("trying ssh-agent key '%s'", keymd5(agent_key))
try:
transport.auth_publickey(username, agent_key)
if transport.is_authenticated():
log("authenticated using agent and key '%s'", keymd5(agent_key))
break
except SSHException:
log("agent key '%s' rejected", keymd5(agent_key), exc_info=True)
if not transport.is_authenticated():
log.info("agent authentication failed, tried %i key%s", len(agent_keys), engs(agent_keys))
def auth_publickey():
log("trying public key authentication using %s", keyfiles)
for keyfile_path in keyfiles:
if not os.path.exists(keyfile_path):
log("no keyfile at '%s'", keyfile_path)
continue
log("trying '%s'", keyfile_path)
key = None
import paramiko
for pkey_classname in ("RSA", "DSS", "ECDSA", "Ed25519"):
pkey_class = getattr(paramiko, "%sKey" % pkey_classname, None)
if pkey_class is None:
log("no %s key type", pkey_classname)
continue
log("trying to load as %s", pkey_classname)
try:
key = pkey_class.from_private_key_file(keyfile_path)
log.info("loaded %s private key from '%s'", pkey_classname, keyfile_path)
break
except PasswordRequiredException as e:
log("%s keyfile requires a passphrase; %s", keyfile_path, e)
passphrase = input_pass("please enter the passphrase for %s:" % (keyfile_path,))
if passphrase:
try:
key = pkey_class.from_private_key_file(keyfile_path, passphrase)
log.info("loaded %s private key from '%s'", pkey_classname, keyfile_path)
except SSHException as e:
log("from_private_key_file", exc_info=True)
log.info("cannot load key from file '%s':", keyfile_path)
log.info(" %s", e)
break
except Exception as e:
log("auth_publickey() loading as %s", pkey_classname, exc_info=True)
key_data = load_binary_file(keyfile_path)
if key_data and key_data.find(b"BEGIN OPENSSH PRIVATE KEY")>=0 and paramiko.__version__<"2.7":
log.warn("Warning: private key '%s'", keyfile_path)
log.warn(" this file seems to be using OpenSSH's own format")
log.warn(" please convert it to something more standard (ie: PEM)")
log.warn(" so it can be used with the paramiko backend")
log.warn(" or switch to the OpenSSH backend with '--ssh=ssh'")
if key:
log("auth_publickey using %s as %s: %s", keyfile_path, pkey_classname, keymd5(key))
try:
transport.auth_publickey(username, key)
except SSHException as e:
log("key '%s' rejected", keyfile_path, exc_info=True)
log.info("SSH authentication using key '%s' failed:", keyfile_path)
log.info(" %s", e)
else:
if transport.is_authenticated():
break
else:
log.error("Error: cannot load private key '%s'", keyfile_path)
def auth_none():
log("trying none authentication")
try:
transport.auth_none(username)
except SSHException:
log("auth_none()", exc_info=True)
def auth_password():
log("trying password authentication")
try:
transport.auth_password(username, password)
except SSHException as e:
log("auth_password(..)", exc_info=True)
log.info("SSH password authentication failed:")
log.info(" %s", getattr(e, "message", e))
def auth_interactive():
log("trying interactive authentication")
class iauthhandler:
def __init__(self):
self.authcount = 0
def handlestuff(self, _title, _instructions, prompt_list):
p = []
for pent in prompt_list:
if self.authcount==0 and password:
p.append(password)
else:
p.append(input_pass(pent[0]))
self.authcount += 1
return p
try:
myiauthhandler = iauthhandler()
transport.auth_interactive(username, myiauthhandler.handlestuff, "")
except SSHException as e:
log("auth_interactive(..)", exc_info=True)
log.info("SSH password authentication failed:")
log.info(" %s", getattr(e, "message", e))
banner = transport.get_banner()
if banner:
log.info("SSH server banner:")
for x in banner.splitlines():
log.info(" %s", x)
if paramiko_config and "auth" in paramiko_config:
auth = paramiko_config.get("auth", "").split("+")
AUTH_OPTIONS = ("none", "agent", "key", "password")
if any(a for a in auth if a not in AUTH_OPTIONS):
raise InitExit(EXIT_SSH_FAILURE, "invalid ssh authentication module specified: %s" %
csv(a for a in auth if a not in AUTH_OPTIONS))
else:
auth = []
if configbool("noneauthentication", NONE_AUTH):
auth.append("none")
if password and configbool("passwordauthentication", PASSWORD_AUTH):
auth.append("password")
if configbool("agentauthentication", AGENT_AUTH):
auth.append("agent")
# Some people do two-factor using KEY_AUTH to kick things off, so this happens first
if configbool("keyauthentication", KEY_AUTH):
auth.append("key")
if not password and configbool("passwordauthentication", PASSWORD_AUTH):
auth.append("password")
#def doauth(authtype):
# return authtype in auth and not transport.is_authenticated()
log("starting authentication, authentication methods: %s", auth)
# per the RFC we probably should do none first always and read off the supported
# methods, however, the current code seems to work fine with OpenSSH
while not transport.is_authenticated() and auth:
a = auth.pop(0)
log("auth=%s", a)
if a=="none":
auth_none()
elif a=="agent":
auth_agent()
elif a=="key":
auth_publickey()
elif a=="password":
auth_interactive()
if not transport.is_authenticated():
if password:
auth_password()
else:
tries = configint("numberofpasswordprompts", PASSWORD_RETRY)
for _ in range(tries):
password = input_pass("please enter the SSH password for %s@%s:" % (username, host))
if not password:
break
auth_password()
if transport.is_authenticated():
break
if not transport.is_authenticated():
transport.close()
raise InitExit(EXIT_CONNECTION_FAILED, "SSH Authentication on %s failed" % host)
class SSHClient (object):
"""
A high-level representation of a session with an SSH server. This class
wraps L{Transport}, L{Channel}, and L{SFTPClient} to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
@since: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by L{save_host_keys}.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If C{filename} is left as C{None}, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
@param filename: the filename to read, or C{None}
@type filename: str
@raise IOError: if a filename was provided and the file could not be
read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked I{after} keys loaded via L{load_system_host_keys},
but will be saved back by L{save_host_keys} (so they can be modified).
The missing host key policy L{AutoAddPolicy} adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
@param filename: the filename to read
@type filename: str
@raise IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
L{load_host_keys} (plus any added directly) will be saved -- not any
host keys loaded with L{load_system_host_keys}.
@param filename: the filename to save to
@type filename: str
@raise IOError: if the file could not be written
"""
f = open(filename, 'w')
f.write('# SSH host keys collected by paramiko\n')
for hostname, keys in self._host_keys.iteritems():
for keytype, key in keys.iteritems():
f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
f.close()
def get_host_keys(self):
"""
Get the local L{HostKeys} object. This can be used to examine the
local host keys or change them.
@return: the local host keys
@rtype: L{HostKeys}
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is C{"paramiko.transport"}
but it can be set to anything you want.
@param name: new channel name for logging
@type name: str
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local L{HostKeys} objects. The
default policy is to reject all unknown servers (using L{RejectPolicy}).
You may substitute L{AutoAddPolicy} or write your own policy class.
@param policy: the policy to use when receiving a host key from a
previously-unknown server
@type policy: L{MissingHostKeyPolicy}
"""
self._policy = policy
def connect(self, hostname, port=22, username=None, password=None, pkey=None,
key_filename=None, timeout=None, allow_agent=True, look_for_keys=True):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see L{load_system_host_keys})
and any local host keys (L{load_host_keys}). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see L{set_missing_host_key_policy}). The default policy is
to reject the key and raise an L{SSHException}.
Authentication is attempted in the following order of priority:
- The C{pkey} or C{key_filename} passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa" or "id_dsa" key discoverable in C{~/.ssh/}
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
@param hostname: the server to connect to
@type hostname: str
@param port: the server port to connect to
@type port: int
@param username: the username to authenticate as (defaults to the
current local username)
@type username: str
@param password: a password to use for authentication or for unlocking
a private key
@type password: str
@param pkey: an optional private key to use for authentication
@type pkey: L{PKey}
@param key_filename: the filename of an optional private key to use
for authentication
@type key_filename: str
@param timeout: an optional timeout (in seconds) for the TCP connect
@type timeout: float
@param allow_agent: set to False to disable connecting to the SSH agent
@type allow_agent: bool
@param look_for_keys: set to False to disable searching for discoverable
private key files in C{~/.ssh/}
@type look_for_keys: bool
@raise BadHostKeyException: if the server's host key could not be
verified
@raise AuthenticationException: if authentication failed
@raise SSHException: if there was any other error connecting or
establishing an SSH session
@raise socket.error: if a socket error occurred while connecting
"""
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
sock.connect((hostname, port))
t = self._transport = Transport(sock)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
our_server_key = self._system_host_keys.get(hostname, {}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(hostname, {}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall out
self._policy.missing_host_key(self, hostname, server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
self._auth(username, password, pkey, key_filename, allow_agent, look_for_keys)
def close(self):
"""
Close this SSHClient and its underlying L{Transport}.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
def exec_command(self, command, bufsize=-1):
"""
Execute a command on the SSH server. A new L{Channel} is opened and
the requested command is executed. The command's input and output
streams are returned as python C{file}-like objects representing
stdin, stdout, and stderr.
@param command: the command to execute
@type command: str
@param bufsize: interpreted the same way as by the built-in C{file()} function in python
@type bufsize: int
@return: the stdin, stdout, and stderr of the executing command
@rtype: tuple(L{ChannelFile}, L{ChannelFile}, L{ChannelFile})
@raise SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session()
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('rb', bufsize)
stderr = chan.makefile_stderr('rb', bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term='vt100', width=80, height=24):
"""
Start an interactive shell session on the SSH server. A new L{Channel}
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
@param term: the terminal type to emulate (for example, C{"vt100"})
@type term: str
@param width: the width (in characters) of the terminal window
@type width: int
@param height: the height (in characters) of the terminal window
@type height: int
@return: a new channel connected to the remote shell
@rtype: L{Channel}
@raise SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
@return: a new SFTP session object
@rtype: L{SFTPClient}
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying L{Transport} object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
@return: the Transport for this connection
@rtype: L{Transport}
"""
return self._transport
def _auth(self, username, password, pkey, key_filename, allow_agent, look_for_keys):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa" or "id_dsa" key discoverable in ~/.ssh/ (if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key.)
"""
saved_exception = None
if pkey is not None:
try:
self._log(DEBUG, 'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
self._transport.auth_publickey(username, pkey)
return
except SSHException, e:
saved_exception = e
if key_filename is not None:
for pkey_class in (RSAKey, DSSKey):
try:
key = pkey_class.from_private_key_file(key_filename, password)
self._log(DEBUG, 'Trying key %s from %s' % (hexlify(key.get_fingerprint()), key_filename))
self._transport.auth_publickey(username, key)
return
except SSHException, e:
saved_exception = e
def do_ssh_paramiko_connect_to(sock, host, port, username, password, proxy_command, remote_xpra, socket_dir, display_as_args, target):
from paramiko import SSHException, Transport, Agent, RSAKey, PasswordRequiredException
from paramiko.hostkeys import HostKeys
transport = Transport(sock)
transport.use_compression(False)
log("SSH transport %s", transport)
try:
transport.start_client()
except SSHException as e:
log("start_client()", exc_info=True)
raise InitException("SSH negotiation failed: %s" % e)
host_key = transport.get_remote_server_key()
assert host_key, "no remote server key"
log("remote_server_key=%s", keymd5(host_key))
if VERIFY_HOSTKEY:
host_keys = HostKeys()
host_keys_filename = None
KNOWN_HOSTS = get_ssh_known_hosts_files()
for known_hosts in KNOWN_HOSTS:
host_keys.clear()
try:
path = os.path.expanduser(known_hosts)
if os.path.exists(path):
host_keys.load(path)
log("HostKeys.load(%s) successful", path)
host_keys_filename = path
break
except IOError:
log("HostKeys.load(%s)", known_hosts, exc_info=True)
log("host keys=%s", host_keys)
keys = host_keys.lookup(host)
known_host_key = (keys or {}).get(host_key.get_name())
def keyname():
return host_key.get_name().replace("ssh-", "")
if host_key==known_host_key:
assert host_key
log("%s host key '%s' OK for host '%s'", keyname(), keymd5(host_key), host)
else:
if known_host_key:
log.warn("Warning: SSH server key mismatch")
qinfo = [
"WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!",
"IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!",
"Someone could be eavesdropping on you right now (man-in-the-middle attack)!",
"It is also possible that a host key has just been changed.",
"The fingerprint for the %s key sent by the remote host is" % keyname(),
keymd5(host_key),
]
if VERIFY_STRICT:
log.warn("Host key verification failed.")
#TODO: show alert with no option to accept key
qinfo += [
"Please contact your system administrator.",
"Add correct host key in %s to get rid of this message.",
"Offending %s key in %s" % (keyname(), host_keys_filename),
"ECDSA host key for %s has changed and you have requested strict checking." % keyname(),
]
sys.stderr.write(os.linesep.join(qinfo))
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "SSH Host key has changed")
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "SSH Host key has changed")
else:
assert (not keys) or (host_key.get_name() not in keys)
if not keys:
log.warn("Warning: unknown SSH host")
else:
log.warn("Warning: unknown %s SSH host key", keyname())
qinfo = [
"The authenticity of host '%s' can't be established." % (host,),
"%s key fingerprint is" % keyname(),
keymd5(host_key),
]
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE, "Unknown SSH host '%s'" % host)
if ADD_KEY:
try:
if not host_keys_filename:
#the first one is the default,
#ie: ~/.ssh/known_hosts on posix
host_keys_filename = os.path.expanduser(KNOWN_HOSTS[0])
log("adding %s key for host '%s' to '%s'", keyname(), host, host_keys_filename)
if not os.path.exists(host_keys_filename):
keys_dir = os.path.dirname(host_keys_filename)
if not os.path.exists(keys_dir):
log("creating keys directory '%s'", keys_dir)
os.mkdir(keys_dir, 0o700)
elif not os.path.isdir(keys_dir):
log.warn("Warning: '%s' is not a directory")
log.warn(" key not saved")
if os.path.exists(keys_dir) and os.path.isdir(keys_dir):
log("creating known host file '%s'", host_keys_filename)
with umask_context(0o133):
with open(host_keys_filename, 'a+'):
pass
host_keys.add(host, host_key.get_name(), host_key)
host_keys.save(host_keys_filename)
except OSError as e:
log("failed to add key to '%s'", host_keys_filename)
log.error("Error adding key to '%s'", host_keys_filename)
log.error(" %s", e)
except Exception as e:
log.error("cannot add key", exc_info=True)
def auth_agent():
agent = Agent()
agent_keys = agent.get_keys()
log("agent keys: %s", agent_keys)
if agent_keys:
for agent_key in agent_keys:
log("trying ssh-agent key '%s'", keymd5(agent_key))
try:
transport.auth_publickey(username, agent_key)
if transport.is_authenticated():
log("authenticated using agent and key '%s'", keymd5(agent_key))
break
except SSHException:
log("agent key '%s' rejected", keymd5(agent_key), exc_info=True)
if not transport.is_authenticated():
log.info("agent authentication failed, tried %i key%s", len(agent_keys), engs(agent_keys))
def auth_publickey():
log("trying public key authentication")
for keyfile in ("id_rsa", "id_dsa"):
keyfile_path = osexpand(os.path.join("~/", ".ssh", keyfile))
if not os.path.exists(keyfile_path):
log("no keyfile at '%s'", keyfile_path)
continue
key = None
try:
key = RSAKey.from_private_key_file(keyfile_path)
except PasswordRequiredException:
log("%s keyfile requires a passphrase", keyfile_path)
passphrase = input_pass("please enter the passphrase for %s:" % (keyfile_path,))
if passphrase:
try:
key = RSAKey.from_private_key_file(keyfile_path, passphrase)
except SSHException as e:
log("from_private_key_file", exc_info=True)
log.info("cannot load key from file '%s':", keyfile_path)
log.info(" %s", e)
if key:
log("auth_publickey using %s: %s", keyfile_path, keymd5(key))
try:
transport.auth_publickey(username, key)
except SSHException as e:
log("key '%s' rejected", keyfile_path, exc_info=True)
log.info("SSH authentication using key '%s' failed:", keyfile_path)
log.info(" %s", e)
else:
if transport.is_authenticated():
break
def auth_none():
log("trying none authentication")
try:
transport.auth_none(username)
except SSHException as e:
log("auth_none()", exc_info=True)
def auth_password():
log("trying password authentication")
try:
transport.auth_password(username, password)
except SSHException as e:
log("auth_password(..)", exc_info=True)
log.info("SSH password authentication failed: %s", e)
banner = transport.get_banner()
if banner:
log.info("SSH server banner:")
for x in banner.splitlines():
log.info(" %s", x)
log("starting authentication")
if not transport.is_authenticated() and NONE_AUTH:
auth_none()
if not transport.is_authenticated() and PASSWORD_AUTH and password:
auth_password()
if not transport.is_authenticated() and AGENT_AUTH:
auth_agent()
if not transport.is_authenticated() and KEY_AUTH:
auth_publickey()
if not transport.is_authenticated() and PASSWORD_AUTH and not password:
for _ in range(1+PASSWORD_RETRY):
password = input_pass("please enter the SSH password for %s@%s" % (username, host))
if not password:
break
auth_password()
if transport.is_authenticated():
break
if not transport.is_authenticated():
transport.close()
raise InitException("SSH Authentication failed")
assert len(remote_xpra)>0
log("will try to run xpra from: %s", remote_xpra)
for xpra_cmd in remote_xpra:
try:
chan = transport.open_session(window_size=None, max_packet_size=0, timeout=60)
chan.set_name("find %s" % xpra_cmd)
except SSHException as e:
log("open_session", exc_info=True)
raise InitException("failed to open SSH session: %s" % e)
cmd = "which %s" % xpra_cmd
log("exec_command('%s')", cmd)
chan.exec_command(cmd)
#poll until the command terminates:
start = monotonic_time()
while not chan.exit_status_ready():
if monotonic_time()-start>10:
chan.close()
raise InitException("SSH test command '%s' timed out" % cmd)
log("exit status is not ready yet, sleeping")
time.sleep(0.01)
r = chan.recv_exit_status()
log("exec_command('%s')=%s", cmd, r)
chan.close()
if r!=0:
continue
cmd = xpra_cmd + " " + " ".join(shellquote(x) for x in proxy_command)
if socket_dir:
cmd += " \"--socket-dir=%s\"" % socket_dir
if display_as_args:
cmd += " "
cmd += " ".join(shellquote(x) for x in display_as_args)
log("cmd(%s, %s)=%s", proxy_command, display_as_args, cmd)
#see https://github.com/paramiko/paramiko/issues/175
#WINDOW_SIZE = 2097152
log("trying to open SSH session, window-size=%i, timeout=%i", WINDOW_SIZE, TIMEOUT)
try:
chan = transport.open_session(window_size=WINDOW_SIZE, max_packet_size=0, timeout=TIMEOUT)
chan.set_name("run-xpra")
except SSHException as e:
log("open_session", exc_info=True)
raise InitException("failed to open SSH session: %s" % e)
else:
log("channel exec_command(%s)" % cmd)
chan.exec_command(cmd)
info = {
"host" : host,
"port" : port,
}
conn = SSHSocketConnection(chan, sock, target, info)
conn.timeout = SOCKET_TIMEOUT
conn.start_stderr_reader()
child = None
conn.process = (child, "ssh", cmd)
return conn
raise Exception("all SSH remote proxy commands have failed")
import os
from pysftp.helpers import known_hosts
from paramiko.hostkeys import HostKeys
if __name__ == '__main__':
h = HostKeys()
try:
kh = known_hosts()
print("known_hosts:", kh)
h.load(os.path.expanduser(kh))
except Exception as e:
print(e)
print(len(h.items()))
class SSHClient (object):
"""
A high-level representation of a session with an SSH server. This class
wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
.. versionadded:: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by `save_host_keys`.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If ``filename`` is left as ``None``, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
:param str filename: the filename to read, or ``None``
:raises IOError:
if a filename was provided and the file could not be read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked after keys loaded via `load_system_host_keys`,
but will be saved back by `save_host_keys` (so they can be modified).
The missing host key policy `.AutoAddPolicy` adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
:param str filename: the filename to read
:raises IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
`load_host_keys` (plus any added directly) will be saved -- not any
host keys loaded with `load_system_host_keys`.
:param str filename: the filename to save to
:raises IOError: if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self._host_keys_filename is not None:
self.load_host_keys(self._host_keys_filename)
with open(filename, 'w') as f:
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
def get_host_keys(self):
"""
Get the local `.HostKeys` object. This can be used to examine the
local host keys or change them.
:return: the local host keys as a `.HostKeys` object.
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is ``"paramiko.transport"``
but it can be set to anything you want.
:param str name: new channel name for logging
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local `.HostKeys` objects. The
default policy is to reject all unknown servers (using `.RejectPolicy`).
You may substitute `.AutoAddPolicy` or write your own policy class.
:param .MissingHostKeyPolicy policy:
the policy to use when receiving a host key from a
previously-unknown server
"""
self._policy = policy
def connect(self, hostname, port=SSH_PORT, username=None, password=None, pkey=None,
key_filename=None, timeout=None, allow_agent=True, look_for_keys=True,
compress=False, sock=None):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see `load_system_host_keys`)
and any local host keys (`load_host_keys`). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see `set_missing_host_key_policy`). The default policy is
to reject the key and raise an `.SSHException`.
Authentication is attempted in the following order of priority:
- The ``pkey`` or ``key_filename`` passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa" or "id_dsa" key discoverable in ``~/.ssh/``
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:param str username:
the username to authenticate as (defaults to the current local
username)
:param str password:
a password to use for authentication or for unlocking a private key
:param .PKey pkey: an optional private key to use for authentication
:param str key_filename:
the filename, or list of filenames, of optional private key(s) to
try for authentication
:param float timeout: an optional timeout (in seconds) for the TCP connect
:param bool allow_agent: set to False to disable connecting to the SSH agent
:param bool look_for_keys:
set to False to disable searching for discoverable private key
files in ``~/.ssh/``
:param bool compress: set to True to turn on compression
:param socket sock:
an open socket or socket-like object (such as a `.Channel`) to use
for communication to the target host
:raises BadHostKeyException: if the server's host key could not be
verified
:raises AuthenticationException: if authentication failed
:raises SSHException: if there was any other error connecting or
establishing an SSH session
:raises socket.error: if a socket error occurred while connecting
"""
if not sock:
for (family, socktype, proto, canonname, sockaddr) in socket.getaddrinfo(hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM):
if socktype == socket.SOCK_STREAM:
af = family
addr = sockaddr
break
else:
# some OS like AIX don't indicate SOCK_STREAM support, so just guess. :(
af, _, _, _, addr = socket.getaddrinfo(hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
t = self._transport = Transport(sock)
t.use_compression(compress=compress)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
our_server_key = self._system_host_keys.get(server_hostkey_name, {}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(server_hostkey_name, {}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall out
self._policy.missing_host_key(self, server_hostkey_name, server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, string_types):
key_filenames = [key_filename]
else:
key_filenames = key_filename
self._auth(username, password, pkey, key_filenames, allow_agent, look_for_keys)
def close(self):
"""
Close this SSHClient and its underlying `.Transport`.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent is not None:
self._agent.close()
self._agent = None
def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
"""
Execute a command on the SSH server. A new `.Channel` is opened and
the requested command is executed. The command's input and output
streams are returned as Python ``file``-like objects representing
stdin, stdout, and stderr.
:param str command: the command to execute
:param int bufsize:
interpreted the same way as by the built-in ``file()`` function in
Python
:param int timeout:
set command's channel timeout. See `Channel.settimeout`.settimeout
:return:
the stdin, stdout, and stderr of the executing command, as a
3-tuple
:raises SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session()
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('r', bufsize)
stderr = chan.makefile_stderr('r', bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term='vt100', width=80, height=24, width_pixels=0,
height_pixels=0):
"""
Start an interactive shell session on the SSH server. A new `.Channel`
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
:param str term:
the terminal type to emulate (for example, ``"vt100"``)
:param int width: the width (in characters) of the terminal window
:param int height: the height (in characters) of the terminal window
:param int width_pixels: the width (in pixels) of the terminal window
:param int height_pixels: the height (in pixels) of the terminal window
:return: a new `.Channel` connected to the remote shell
:raises SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
:return: a new `.SFTPClient` session object
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying `.Transport` object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
:return: the `.Transport` for this connection
"""
return self._transport
def _auth(self, username, password, pkey, key_filenames, allow_agent, look_for_keys):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa" or "id_dsa" key discoverable in ~/.ssh/ (if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = []
if pkey is not None:
try:
self._log(DEBUG, 'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
allowed_types = self._transport.auth_publickey(username, pkey)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
except SSHException as e:
saved_exception = e
if not two_factor:
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey):
try:
key = pkey_class.from_private_key_file(key_filename, password)
self._log(DEBUG, 'Trying key %s from %s' % (hexlify(key.get_fingerprint()), key_filename))
self._transport.auth_publickey(username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor and allow_agent:
if self._agent is None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(DEBUG, 'Trying SSH agent key %s' % hexlify(key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor:
keyfiles = []
rsa_key = os.path.expanduser('~/.ssh/id_rsa')
dsa_key = os.path.expanduser('~/.ssh/id_dsa')
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
# look in ~/ssh/ for windows users:
rsa_key = os.path.expanduser('~/ssh/id_rsa')
dsa_key = os.path.expanduser('~/ssh/id_dsa')
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
if not look_for_keys:
keyfiles = []
for pkey_class, filename in keyfiles:
try:
key = pkey_class.from_private_key_file(filename, password)
self._log(DEBUG, 'Trying discovered key %s in %s' % (hexlify(key.get_fingerprint()), filename))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(username, key)
two_factor = (allowed_types == ['password'])
if not two_factor:
return
break
except (SSHException, IOError) as e:
saved_exception = e
if password is not None:
try:
self._transport.auth_password(username, password)
return
except SSHException as e:
saved_exception = e
elif two_factor:
raise SSHException('Two-factor authentication requires a password')
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException('No authentication methods available')
def _log(self, level, msg):
self._transport._log(level, msg)
class SSHClient(object):
"""
A high-level representation of a session with an SSH server. This class
wraps L{Transport}, L{Channel}, and L{SFTPClient} to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
@since: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by L{save_host_keys}.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If C{filename} is left as C{None}, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
@param filename: the filename to read, or C{None}
@type filename: str
@raise IOError: if a filename was provided and the file could not be
read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked I{after} keys loaded via L{load_system_host_keys},
but will be saved back by L{save_host_keys} (so they can be modified).
The missing host key policy L{AutoAddPolicy} adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
@param filename: the filename to read
@type filename: str
@raise IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
L{load_host_keys} (plus any added directly) will be saved -- not any
host keys loaded with L{load_system_host_keys}.
@param filename: the filename to save to
@type filename: str
@raise IOError: if the file could not be written
"""
f = open(filename, 'w')
f.write('# SSH host keys collected by paramiko\n')
for hostname, keys in self._host_keys.iteritems():
for keytype, key in keys.iteritems():
f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))
f.close()
def get_host_keys(self):
"""
Get the local L{HostKeys} object. This can be used to examine the
local host keys or change them.
@return: the local host keys
@rtype: L{HostKeys}
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is C{"paramiko.transport"}
but it can be set to anything you want.
@param name: new channel name for logging
@type name: str
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local L{HostKeys} objects. The
default policy is to reject all unknown servers (using L{RejectPolicy}).
You may substitute L{AutoAddPolicy} or write your own policy class.
@param policy: the policy to use when receiving a host key from a
previously-unknown server
@type policy: L{MissingHostKeyPolicy}
"""
self._policy = policy
def connect(self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see L{load_system_host_keys})
and any local host keys (L{load_host_keys}). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see L{set_missing_host_key_policy}). The default policy is
to reject the key and raise an L{SSHException}.
Authentication is attempted in the following order of priority:
- The C{pkey} or C{key_filename} passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa" or "id_dsa" key discoverable in C{~/.ssh/}
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
@param hostname: the server to connect to
@type hostname: str
@param port: the server port to connect to
@type port: int
@param username: the username to authenticate as (defaults to the
current local username)
@type username: str
@param password: a password to use for authentication or for unlocking
a private key
@type password: str
@param pkey: an optional private key to use for authentication
@type pkey: L{PKey}
@param key_filename: the filename, or list of filenames, of optional
private key(s) to try for authentication
@type key_filename: str or list(str)
@param timeout: an optional timeout (in seconds) for the TCP connect
@type timeout: float
@param allow_agent: set to False to disable connecting to the SSH agent
@type allow_agent: bool
@param look_for_keys: set to False to disable searching for discoverable
private key files in C{~/.ssh/}
@type look_for_keys: bool
@raise BadHostKeyException: if the server's host key could not be
verified
@raise AuthenticationException: if authentication failed
@raise SSHException: if there was any other error connecting or
establishing an SSH session
@raise socket.error: if a socket error occurred while connecting
"""
for (family, socktype, proto, canonname,
sockaddr) in socket.getaddrinfo(hostname, port, socket.AF_UNSPEC,
socket.SOCK_STREAM):
if socktype == socket.SOCK_STREAM:
af = family
addr = sockaddr
break
else:
raise SSHException('No suitable address family for %s' % hostname)
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
sock.connect(addr)
t = self._transport = Transport(sock)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
our_server_key = self._system_host_keys.get(server_hostkey_name,
{}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(server_hostkey_name,
{}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall out
self._policy.missing_host_key(self, server_hostkey_name,
server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, (str, unicode)):
key_filenames = [key_filename]
else:
key_filenames = key_filename
self._auth(username, password, pkey, key_filenames, allow_agent,
look_for_keys)
def close(self):
"""
Close this SSHClient and its underlying L{Transport}.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
def exec_command(self, command, bufsize=-1):
"""
Execute a command on the SSH server. A new L{Channel} is opened and
the requested command is executed. The command's input and output
streams are returned as python C{file}-like objects representing
stdin, stdout, and stderr.
@param command: the command to execute
@type command: str
@param bufsize: interpreted the same way as by the built-in C{file()} function in python
@type bufsize: int
@return: the stdin, stdout, and stderr of the executing command
@rtype: tuple(L{ChannelFile}, L{ChannelFile}, L{ChannelFile})
@raise SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session()
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('rb', bufsize)
stderr = chan.makefile_stderr('rb', bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term='vt100', width=80, height=24):
"""
Start an interactive shell session on the SSH server. A new L{Channel}
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
@param term: the terminal type to emulate (for example, C{"vt100"})
@type term: str
@param width: the width (in characters) of the terminal window
@type width: int
@param height: the height (in characters) of the terminal window
@type height: int
@return: a new channel connected to the remote shell
@rtype: L{Channel}
@raise SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
@return: a new SFTP session object
@rtype: L{SFTPClient}
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying L{Transport} object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
@return: the Transport for this connection
@rtype: L{Transport}
"""
return self._transport
def _auth(self, username, password, pkey, key_filenames, allow_agent,
look_for_keys):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa" or "id_dsa" key discoverable in ~/.ssh/ (if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key.)
"""
saved_exception = None
if pkey is not None:
try:
self._log(
DEBUG,
'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
self._transport.auth_publickey(username, pkey)
return
except SSHException, e:
saved_exception = e
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey):
try:
key = pkey_class.from_private_key_file(
key_filename, password)
self._log(
DEBUG, 'Trying key %s from %s' %
(hexlify(key.get_fingerprint()), key_filename))
self._transport.auth_publickey(username, key)
return
except SSHException, e:
saved_exception = e
def do_ssh_paramiko_connect_to(transport,
host,
username,
password,
host_config=None):
from paramiko import SSHException, RSAKey, PasswordRequiredException
from paramiko.agent import Agent
from paramiko.hostkeys import HostKeys
log("do_ssh_paramiko_connect_to%s",
(transport, host, username, password, host_config))
log("SSH transport %s", transport)
host_key = transport.get_remote_server_key()
assert host_key, "no remote server key"
log("remote_server_key=%s", keymd5(host_key))
if VERIFY_HOSTKEY:
host_keys = HostKeys()
host_keys_filename = None
KNOWN_HOSTS = get_ssh_known_hosts_files()
for known_hosts in KNOWN_HOSTS:
host_keys.clear()
try:
path = os.path.expanduser(known_hosts)
if os.path.exists(path):
host_keys.load(path)
log("HostKeys.load(%s) successful", path)
host_keys_filename = path
break
except IOError:
log("HostKeys.load(%s)", known_hosts, exc_info=True)
log("host keys=%s", host_keys)
keys = host_keys.lookup(host)
known_host_key = (keys or {}).get(host_key.get_name())
def keyname():
return host_key.get_name().replace("ssh-", "")
if host_key == known_host_key:
assert host_key
log("%s host key '%s' OK for host '%s'", keyname(),
keymd5(host_key), host)
else:
dnscheck = ""
if host_config:
verifyhostkeydns = host_config.get("verifyhostkeydns")
if verifyhostkeydns and verifyhostkeydns.lower(
) in TRUE_OPTIONS:
try:
from xpra.net.sshfp import check_host_key
dnscheck = check_host_key(host, host_key)
except ImportError as e:
log("verifyhostkeydns failed", exc_info=True)
log.warn("Warning: cannot check SSHFP DNS records")
log.warn(" %s", e)
log.info("dnscheck=%s", dnscheck)
def adddnscheckinfo(q):
if dnscheck is not True:
q += ["SSHFP validation failed:", dnscheck]
if dnscheck is True:
#DNSSEC provided a matching record
log.info("found a valid SSHFP record for host %s", host)
elif known_host_key:
log.warn("Warning: SSH server key mismatch")
qinfo = [
"WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!",
"IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!",
"Someone could be eavesdropping on you right now (man-in-the-middle attack)!",
"It is also possible that a host key has just been changed.",
"The fingerprint for the %s key sent by the remote host is"
% keyname(),
keymd5(host_key),
]
adddnscheckinfo(qinfo)
if VERIFY_STRICT:
log.warn("Host key verification failed.")
#TODO: show alert with no option to accept key
qinfo += [
"Please contact your system administrator.",
"Add correct host key in %s to get rid of this message.",
"Offending %s key in %s" %
(keyname(), host_keys_filename),
"ECDSA host key for %s has changed and you have requested strict checking."
% keyname(),
]
sys.stderr.write(os.linesep.join(qinfo))
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE,
"SSH Host key has changed")
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE,
"SSH Host key has changed")
else:
assert (not keys) or (host_key.get_name() not in keys)
if not keys:
log.warn("Warning: unknown SSH host")
else:
log.warn("Warning: unknown %s SSH host key", keyname())
qinfo = [
"The authenticity of host '%s' can't be established." %
(host, ),
"%s key fingerprint is" % keyname(),
keymd5(host_key),
]
adddnscheckinfo(qinfo)
if not confirm_key(qinfo):
transport.close()
raise InitExit(EXIT_SSH_KEY_FAILURE,
"Unknown SSH host '%s'" % host)
if ADD_KEY:
try:
if not host_keys_filename:
#the first one is the default,
#ie: ~/.ssh/known_hosts on posix
host_keys_filename = os.path.expanduser(KNOWN_HOSTS[0])
log("adding %s key for host '%s' to '%s'", keyname(), host,
host_keys_filename)
if not os.path.exists(host_keys_filename):
keys_dir = os.path.dirname(host_keys_filename)
if not os.path.exists(keys_dir):
log("creating keys directory '%s'", keys_dir)
os.mkdir(keys_dir, 0o700)
elif not os.path.isdir(keys_dir):
log.warn("Warning: '%s' is not a directory")
log.warn(" key not saved")
if os.path.exists(keys_dir) and os.path.isdir(
keys_dir):
log("creating known host file '%s'",
host_keys_filename)
with umask_context(0o133):
with open(host_keys_filename, 'a+'):
pass
host_keys.add(host, host_key.get_name(), host_key)
host_keys.save(host_keys_filename)
except OSError as e:
log("failed to add key to '%s'", host_keys_filename)
log.error("Error adding key to '%s'", host_keys_filename)
log.error(" %s", e)
except Exception as e:
log.error("cannot add key", exc_info=True)
def auth_agent():
agent = Agent()
agent_keys = agent.get_keys()
log("agent keys: %s", agent_keys)
if agent_keys:
for agent_key in agent_keys:
log("trying ssh-agent key '%s'", keymd5(agent_key))
try:
transport.auth_publickey(username, agent_key)
if transport.is_authenticated():
log("authenticated using agent and key '%s'",
keymd5(agent_key))
break
except SSHException:
log("agent key '%s' rejected",
keymd5(agent_key),
exc_info=True)
if not transport.is_authenticated():
log.info("agent authentication failed, tried %i key%s",
len(agent_keys), engs(agent_keys))
def auth_publickey():
log("trying public key authentication")
for keyfile in ("id_rsa", "id_dsa"):
keyfile_path = osexpand(os.path.join("~/", ".ssh", keyfile))
if not os.path.exists(keyfile_path):
log("no keyfile at '%s'", keyfile_path)
continue
key = None
try:
key = RSAKey.from_private_key_file(keyfile_path)
except PasswordRequiredException:
log("%s keyfile requires a passphrase", keyfile_path)
passphrase = input_pass("please enter the passphrase for %s:" %
(keyfile_path, ))
if passphrase:
try:
key = RSAKey.from_private_key_file(
keyfile_path, passphrase)
except SSHException as e:
log("from_private_key_file", exc_info=True)
log.info("cannot load key from file '%s':",
keyfile_path)
log.info(" %s", e)
if key:
log("auth_publickey using %s: %s", keyfile_path, keymd5(key))
try:
transport.auth_publickey(username, key)
except SSHException as e:
log("key '%s' rejected", keyfile_path, exc_info=True)
log.info("SSH authentication using key '%s' failed:",
keyfile_path)
log.info(" %s", e)
else:
if transport.is_authenticated():
break
def auth_none():
log("trying none authentication")
try:
transport.auth_none(username)
except SSHException as e:
log("auth_none()", exc_info=True)
def auth_password():
log("trying password authentication")
try:
transport.auth_password(username, password)
except SSHException as e:
log("auth_password(..)", exc_info=True)
log.info("SSH password authentication failed: %s", e)
def auth_interactive():
log("trying interactive authentication")
class iauthhandler:
def __init__(self):
self.authcount = 0
def handlestuff(self, title, instructions, prompt_list):
p = []
for pent in prompt_list:
if self.authcount == 0 and password:
p.append(password)
else:
p.append(input_pass(pent[0]))
self.authcount += 1
return p
try:
myiauthhandler = iauthhandler()
transport.auth_interactive(username, myiauthhandler.handlestuff,
"")
except SSHException as e:
log("auth_interactive(..)", exc_info=True)
log.info("SSH password authentication failed: %s", e)
banner = transport.get_banner()
if banner:
log.info("SSH server banner:")
for x in banner.splitlines():
log.info(" %s", x)
log("starting authentication")
# per the RFC we probably should do none first always and read off the supported
# methods, however, the current code seems to work fine with OpenSSH
if not transport.is_authenticated() and NONE_AUTH:
auth_none()
# Some people do two-factor using KEY_AUTH to kick things off, so this happens first
if not transport.is_authenticated() and KEY_AUTH:
auth_publickey()
if not transport.is_authenticated() and PASSWORD_AUTH:
auth_interactive()
if not transport.is_authenticated() and PASSWORD_AUTH and password:
auth_password()
if not transport.is_authenticated() and AGENT_AUTH:
auth_agent()
if not transport.is_authenticated() and PASSWORD_AUTH and not password:
for _ in range(1 + PASSWORD_RETRY):
password = input_pass("please enter the SSH password for %s@%s" %
(username, host))
if not password:
break
auth_password()
if transport.is_authenticated():
break
if not transport.is_authenticated():
transport.close()
raise InitException("SSH Authentication on %s failed" % host)
class SSHClient (ClosingContextManager):
"""
A high-level representation of a session with an SSH server. This class
wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
Instances of this class may be used as context managers.
.. versionadded:: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by `save_host_keys`.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If ``filename`` is left as ``None``, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
:param str filename: the filename to read, or ``None``
:raises: ``IOError`` --
if a filename was provided and the file could not be read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked after keys loaded via `load_system_host_keys`,
but will be saved back by `save_host_keys` (so they can be modified).
The missing host key policy `.AutoAddPolicy` adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
:param str filename: the filename to read
:raises: ``IOError`` -- if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
`load_host_keys` (plus any added directly) will be saved -- not any
host keys loaded with `load_system_host_keys`.
:param str filename: the filename to save to
:raises: ``IOError`` -- if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self._host_keys_filename is not None:
self.load_host_keys(self._host_keys_filename)
with open(filename, 'w') as f:
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write('%s %s %s\n' % (
hostname, keytype, key.get_base64()))
def get_host_keys(self):
"""
Get the local `.HostKeys` object. This can be used to examine the
local host keys or change them.
:return: the local host keys as a `.HostKeys` object.
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is ``"paramiko.transport"``
but it can be set to anything you want.
:param str name: new channel name for logging
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set policy to use when connecting to servers without a known host key.
Specifically:
* A **policy** is a "policy class" (or instance thereof), namely some
subclass of `.MissingHostKeyPolicy` such as `.RejectPolicy` (the
default), `.AutoAddPolicy`, `.WarningPolicy`, or a user-created
subclass.
* A host key is **known** when it appears in the client object's cached
host keys structures (those manipulated by `load_system_host_keys`
and/or `load_host_keys`).
:param .MissingHostKeyPolicy policy:
the policy to use when receiving a host key from a
previously-unknown server
"""
if inspect.isclass(policy):
policy = policy()
self._policy = policy
def _families_and_addresses(self, hostname, port):
"""
Yield pairs of address families and addresses to try for connecting.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:returns: Yields an iterable of ``(family, address)`` tuples
"""
guess = True
addrinfos = socket.getaddrinfo(
hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
for (family, socktype, proto, canonname, sockaddr) in addrinfos:
if socktype == socket.SOCK_STREAM:
yield family, sockaddr
guess = False
# some OS like AIX don't indicate SOCK_STREAM support, so just
# guess. :( We only do this if we did not get a single result marked
# as socktype == SOCK_STREAM.
if guess:
for family, _, _, _, sockaddr in addrinfos:
yield family, sockaddr
def connect(
self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True,
compress=False,
sock=None,
gss_auth=False,
gss_kex=False,
gss_deleg_creds=True,
gss_host=None,
banner_timeout=None,
auth_timeout=None,
gss_trust_dns=True,
):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see `load_system_host_keys`)
and any local host keys (`load_host_keys`). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see `set_missing_host_key_policy`). The default policy is
to reject the key and raise an `.SSHException`.
Authentication is attempted in the following order of priority:
- The ``pkey`` or ``key_filename`` passed in (if any)
- ``key_filename`` may contain OpenSSH public certificate paths
as well as regular private-key paths; when files ending in
``-cert.pub`` are found, they are assumed to match a private
key, and both components will be loaded. (The private key
itself does *not* need to be listed in ``key_filename`` for
this to occur - *just* the certificate.)
- Any key we can find through an SSH agent
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in
``~/.ssh/``
- When OpenSSH-style public certificates exist that match an
existing such private key (so e.g. one has ``id_rsa`` and
``id_rsa-cert.pub``) the certificate will be loaded alongside
the private key and used for authentication.
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:param str username:
the username to authenticate as (defaults to the current local
username)
:param str password:
a password to use for authentication or for unlocking a private key
:param .PKey pkey: an optional private key to use for authentication
:param str key_filename:
the filename, or list of filenames, of optional private key(s)
and/or certs to try for authentication
:param float timeout:
an optional timeout (in seconds) for the TCP connect
:param bool allow_agent:
set to False to disable connecting to the SSH agent
:param bool look_for_keys:
set to False to disable searching for discoverable private key
files in ``~/.ssh/``
:param bool compress: set to True to turn on compression
:param socket sock:
an open socket or socket-like object (such as a `.Channel`) to use
for communication to the target host
:param bool gss_auth:
``True`` if you want to use GSS-API authentication
:param bool gss_kex:
Perform GSS-API Key Exchange and user authentication
:param bool gss_deleg_creds: Delegate GSS-API client credentials or not
:param str gss_host:
The targets name in the kerberos database. default: hostname
:param bool gss_trust_dns:
Indicates whether or not the DNS is trusted to securely
canonicalize the name of the host being connected to (default
``True``).
:param float banner_timeout: an optional timeout (in seconds) to wait
for the SSH banner to be presented.
:param float auth_timeout: an optional timeout (in seconds) to wait for
an authentication response.
:raises:
`.BadHostKeyException` -- if the server's host key could not be
verified
:raises: `.AuthenticationException` -- if authentication failed
:raises:
`.SSHException` -- if there was any other error connecting or
establishing an SSH session
:raises socket.error: if a socket error occurred while connecting
.. versionchanged:: 1.15
Added the ``banner_timeout``, ``gss_auth``, ``gss_kex``,
``gss_deleg_creds`` and ``gss_host`` arguments.
.. versionchanged:: 2.3
Added the ``gss_trust_dns`` argument.
"""
if not sock:
errors = {}
# Try multiple possible address families (e.g. IPv4 vs IPv6)
to_try = list(self._families_and_addresses(hostname, port))
for af, addr in to_try:
try:
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
# Break out of the loop on success
break
except socket.error as e:
# Raise anything that isn't a straight up connection error
# (such as a resolution error)
if e.errno not in (ECONNREFUSED, EHOSTUNREACH):
raise
# Capture anything else so we know how the run looks once
# iteration is complete. Retain info about which attempt
# this was.
errors[addr] = e
# Make sure we explode usefully if no address family attempts
# succeeded. We've no way of knowing which error is the "right"
# one, so we construct a hybrid exception containing all the real
# ones, of a subclass that client code should still be watching for
# (socket.error)
if len(errors) == len(to_try):
raise NoValidConnectionsError(errors)
t = self._transport = Transport(
sock, gss_kex=gss_kex, gss_deleg_creds=gss_deleg_creds
)
t.use_compression(compress=compress)
t.set_gss_host(
kex_requested=gss_kex,
gss_host=gss_host,
trust_dns=gss_trust_dns,
)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
if banner_timeout is not None:
t.banner_timeout = banner_timeout
if auth_timeout is not None:
t.auth_timeout = auth_timeout
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
our_server_keys = None
our_server_keys = self._system_host_keys.get(server_hostkey_name)
if our_server_keys is None:
our_server_keys = self._host_keys.get(server_hostkey_name)
if our_server_keys is not None:
keytype = our_server_keys.keys()[0]
sec_opts = t.get_security_options()
other_types = [x for x in sec_opts.key_types if x != keytype]
sec_opts.key_types = [keytype] + other_types
t.start_client(timeout=timeout)
# If GSS-API Key Exchange is performed we are not required to check the
# host key, because the host is authenticated via GSS-API / SSPI as
# well as our client.
if not self._transport.gss_kex_used:
server_key = t.get_remote_server_key()
if our_server_keys is None:
# will raise exception if the key is rejected
self._policy.missing_host_key(
self, server_hostkey_name, server_key
)
else:
our_key = our_server_keys.get(server_key.get_name())
if our_key != server_key:
if our_key is None:
our_key = list(our_server_keys.values())[0]
raise BadHostKeyException(hostname, server_key, our_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, string_types):
key_filenames = [key_filename]
else:
key_filenames = key_filename
self._auth(
username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, t.gss_host,
)
def close(self):
"""
Close this SSHClient and its underlying `.Transport`.
.. warning::
Failure to do this may, in some situations, cause your Python
interpreter to hang at shutdown (often due to race conditions).
It's good practice to `close` your client objects anytime you're
done using them, instead of relying on garbage collection.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent is not None:
self._agent.close()
self._agent = None
def exec_command(
self,
command,
bufsize=-1,
timeout=None,
get_pty=False,
environment=None,
):
"""
Execute a command on the SSH server. A new `.Channel` is opened and
the requested command is executed. The command's input and output
streams are returned as Python ``file``-like objects representing
stdin, stdout, and stderr.
:param str command: the command to execute
:param int bufsize:
interpreted the same way as by the built-in ``file()`` function in
Python
:param int timeout:
set command's channel timeout. See `.Channel.settimeout`
:param dict environment:
a dict of shell environment variables, to be merged into the
default environment that the remote command executes within.
.. warning::
Servers may silently reject some environment variables; see the
warning in `.Channel.set_environment_variable` for details.
:return:
the stdin, stdout, and stderr of the executing command, as a
3-tuple
:raises: `.SSHException` -- if the server fails to execute the command
"""
chan = self._transport.open_session(timeout=timeout)
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
if environment:
chan.update_environment(environment)
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('r', bufsize)
stderr = chan.makefile_stderr('r', bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term='vt100', width=80, height=24, width_pixels=0,
height_pixels=0, environment=None):
"""
Start an interactive shell session on the SSH server. A new `.Channel`
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
:param str term:
the terminal type to emulate (for example, ``"vt100"``)
:param int width: the width (in characters) of the terminal window
:param int height: the height (in characters) of the terminal window
:param int width_pixels: the width (in pixels) of the terminal window
:param int height_pixels: the height (in pixels) of the terminal window
:param dict environment: the command's environment
:return: a new `.Channel` connected to the remote shell
:raises: `.SSHException` -- if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
:return: a new `.SFTPClient` session object
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying `.Transport` object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
:return: the `.Transport` for this connection
"""
return self._transport
def _key_from_filepath(self, filename, klass, password):
"""
Attempt to derive a `.PKey` from given string path ``filename``:
- If ``filename`` appears to be a cert, the matching private key is
loaded.
- Otherwise, the filename is assumed to be a private key, and the
matching public cert will be loaded if it exists.
"""
cert_suffix = '-cert.pub'
# Assume privkey, not cert, by default
if filename.endswith(cert_suffix):
key_path = filename[:-len(cert_suffix)]
cert_path = filename
else:
key_path = filename
cert_path = filename + cert_suffix
# Blindly try the key path; if no private key, nothing will work.
key = klass.from_private_key_file(key_path, password)
# TODO: change this to 'Loading' instead of 'Trying' sometime; probably
# when #387 is released, since this is a critical log message users are
# likely testing/filtering for (bah.)
msg = "Trying discovered key {0} in {1}".format(
hexlify(key.get_fingerprint()), key_path,
)
self._log(DEBUG, msg)
# Attempt to load cert if it exists.
if os.path.isfile(cert_path):
key.load_certificate(cert_path)
self._log(DEBUG, "Adding public certificate {0}".format(cert_path))
return key
def _auth(self, username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host):
"""
Try, in order:
- The key(s) passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in ~/.ssh/
(if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = set()
two_factor_types = set(['keyboard-interactive', 'password'])
# If GSS-API support and GSS-PI Key Exchange was performed, we attempt
# authentication with gssapi-keyex.
if gss_kex and self._transport.gss_kex_used:
try:
self._transport.auth_gssapi_keyex(username)
return
except Exception as e:
saved_exception = e
# Try GSS-API authentication (gssapi-with-mic) only if GSS-API Key
# Exchange is not performed, because if we use GSS-API for the key
# exchange, there is already a fully established GSS-API context, so
# why should we do that again?
if gss_auth:
try:
return self._transport.auth_gssapi_with_mic(
username, gss_host, gss_deleg_creds,
)
except Exception as e:
saved_exception = e
if pkey is not None:
try:
self._log(
DEBUG,
'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
allowed_types = set(
self._transport.auth_publickey(username, pkey))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
except SSHException as e:
saved_exception = e
if not two_factor:
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey, ECDSAKey, Ed25519Key):
try:
key = self._key_from_filepath(
key_filename, pkey_class, password,
)
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor and allow_agent:
if self._agent is None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(
DEBUG,
'Trying SSH agent key %s' % hexlify(
key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key password
# will return an allowed 2fac auth method
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor:
keyfiles = []
for keytype, name in [
(RSAKey, "rsa"),
(DSSKey, "dsa"),
(ECDSAKey, "ecdsa"),
(Ed25519Key, "ed25519"),
]:
# ~/ssh/ is for windows
for directory in [".ssh", "ssh"]:
full_path = os.path.expanduser(
"~/%s/id_%s" % (directory, name)
)
if os.path.isfile(full_path):
# TODO: only do this append if below did not run
keyfiles.append((keytype, full_path))
if os.path.isfile(full_path + '-cert.pub'):
keyfiles.append((keytype, full_path + '-cert.pub'))
if not look_for_keys:
keyfiles = []
for pkey_class, filename in keyfiles:
try:
key = self._key_from_filepath(
filename, pkey_class, password,
)
# for 2-factor auth a successfully auth'd key will result
# in ['password']
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except (SSHException, IOError) as e:
saved_exception = e
if password is not None:
try:
self._transport.auth_password(username, password)
return
except SSHException as e:
saved_exception = e
elif two_factor:
try:
self._transport.auth_interactive_dumb(username)
return
except SSHException as e:
saved_exception = e
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException('No authentication methods available')
def _log(self, level, msg):
self._transport._log(level, msg)
class SSHClient(ClosingContextManager):
"""
A high-level representation of a session with an SSH server. This class
wraps `.Transport`, `.Channel`, and `.SFTPClient` to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
Instances of this class may be used as context managers.
.. versionadded:: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by `save_host_keys`.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If ``filename`` is left as ``None``, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
:param str filename: the filename to read, or ``None``
:raises: ``IOError`` --
if a filename was provided and the file could not be read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser('~/.ssh/known_hosts')
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked after keys loaded via `load_system_host_keys`,
but will be saved back by `save_host_keys` (so they can be modified).
The missing host key policy `.AutoAddPolicy` adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
:param str filename: the filename to read
:raises: ``IOError`` -- if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
`load_host_keys` (plus any added directly) will be saved -- not any
host keys loaded with `load_system_host_keys`.
:param str filename: the filename to save to
:raises: ``IOError`` -- if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self._host_keys_filename is not None:
self.load_host_keys(self._host_keys_filename)
with open(filename, 'w') as f:
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write('%s %s %s\n' %
(hostname, keytype, key.get_base64()))
def get_host_keys(self):
"""
Get the local `.HostKeys` object. This can be used to examine the
local host keys or change them.
:return: the local host keys as a `.HostKeys` object.
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is ``"paramiko.transport"``
but it can be set to anything you want.
:param str name: new channel name for logging
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set policy to use when connecting to servers without a known host key.
Specifically:
* A **policy** is a "policy class" (or instance thereof), namely some
subclass of `.MissingHostKeyPolicy` such as `.RejectPolicy` (the
default), `.AutoAddPolicy`, `.WarningPolicy`, or a user-created
subclass.
* A host key is **known** when it appears in the client object's cached
host keys structures (those manipulated by `load_system_host_keys`
and/or `load_host_keys`).
:param .MissingHostKeyPolicy policy:
the policy to use when receiving a host key from a
previously-unknown server
"""
if inspect.isclass(policy):
policy = policy()
self._policy = policy
def _families_and_addresses(self, hostname, port):
"""
Yield pairs of address families and addresses to try for connecting.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:returns: Yields an iterable of ``(family, address)`` tuples
"""
guess = True
addrinfos = socket.getaddrinfo(hostname, port, socket.AF_UNSPEC,
socket.SOCK_STREAM)
for (family, socktype, proto, canonname, sockaddr) in addrinfos:
if socktype == socket.SOCK_STREAM:
yield family, sockaddr
guess = False
# some OS like AIX don't indicate SOCK_STREAM support, so just
# guess. :( We only do this if we did not get a single result marked
# as socktype == SOCK_STREAM.
if guess:
for family, _, _, _, sockaddr in addrinfos:
yield family, sockaddr
def connect(
self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True,
compress=False,
sock=None,
gss_auth=False,
gss_kex=False,
gss_deleg_creds=True,
gss_host=None,
banner_timeout=None,
auth_timeout=None,
gss_trust_dns=True,
):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see `load_system_host_keys`)
and any local host keys (`load_host_keys`). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see `set_missing_host_key_policy`). The default policy is
to reject the key and raise an `.SSHException`.
Authentication is attempted in the following order of priority:
- The ``pkey`` or ``key_filename`` passed in (if any)
- ``key_filename`` may contain OpenSSH public certificate paths
as well as regular private-key paths; when files ending in
``-cert.pub`` are found, they are assumed to match a private
key, and both components will be loaded. (The private key
itself does *not* need to be listed in ``key_filename`` for
this to occur - *just* the certificate.)
- Any key we can find through an SSH agent
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in
``~/.ssh/``
- When OpenSSH-style public certificates exist that match an
existing such private key (so e.g. one has ``id_rsa`` and
``id_rsa-cert.pub``) the certificate will be loaded alongside
the private key and used for authentication.
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
:param str hostname: the server to connect to
:param int port: the server port to connect to
:param str username:
the username to authenticate as (defaults to the current local
username)
:param str password:
a password to use for authentication or for unlocking a private key
:param .PKey pkey: an optional private key to use for authentication
:param str key_filename:
the filename, or list of filenames, of optional private key(s)
and/or certs to try for authentication
:param float timeout:
an optional timeout (in seconds) for the TCP connect
:param bool allow_agent:
set to False to disable connecting to the SSH agent
:param bool look_for_keys:
set to False to disable searching for discoverable private key
files in ``~/.ssh/``
:param bool compress: set to True to turn on compression
:param socket sock:
an open socket or socket-like object (such as a `.Channel`) to use
for communication to the target host
:param bool gss_auth:
``True`` if you want to use GSS-API authentication
:param bool gss_kex:
Perform GSS-API Key Exchange and user authentication
:param bool gss_deleg_creds: Delegate GSS-API client credentials or not
:param str gss_host:
The targets name in the kerberos database. default: hostname
:param bool gss_trust_dns:
Indicates whether or not the DNS is trusted to securely
canonicalize the name of the host being connected to (default
``True``).
:param float banner_timeout: an optional timeout (in seconds) to wait
for the SSH banner to be presented.
:param float auth_timeout: an optional timeout (in seconds) to wait for
an authentication response.
:raises:
`.BadHostKeyException` -- if the server's host key could not be
verified
:raises: `.AuthenticationException` -- if authentication failed
:raises:
`.SSHException` -- if there was any other error connecting or
establishing an SSH session
:raises socket.error: if a socket error occurred while connecting
.. versionchanged:: 1.15
Added the ``banner_timeout``, ``gss_auth``, ``gss_kex``,
``gss_deleg_creds`` and ``gss_host`` arguments.
.. versionchanged:: 2.3
Added the ``gss_trust_dns`` argument.
"""
if not sock:
errors = {}
# Try multiple possible address families (e.g. IPv4 vs IPv6)
to_try = list(self._families_and_addresses(hostname, port))
for af, addr in to_try:
try:
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
# Break out of the loop on success
break
except socket.error as e:
# Raise anything that isn't a straight up connection error
# (such as a resolution error)
if e.errno not in (ECONNREFUSED, EHOSTUNREACH):
raise
# Capture anything else so we know how the run looks once
# iteration is complete. Retain info about which attempt
# this was.
errors[addr] = e
# Make sure we explode usefully if no address family attempts
# succeeded. We've no way of knowing which error is the "right"
# one, so we construct a hybrid exception containing all the real
# ones, of a subclass that client code should still be watching for
# (socket.error)
if len(errors) == len(to_try):
raise NoValidConnectionsError(errors)
t = self._transport = Transport(sock,
gss_kex=gss_kex,
gss_deleg_creds=gss_deleg_creds)
t.use_compression(compress=compress)
t.set_gss_host(
# t.hostname may be None, but GSS-API requires a target name.
# Therefore use hostname as fallback.
gss_host=gss_host or hostname,
trust_dns=gss_trust_dns,
gssapi_requested=gss_auth or gss_kex,
)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
if banner_timeout is not None:
t.banner_timeout = banner_timeout
if auth_timeout is not None:
t.auth_timeout = auth_timeout
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
our_server_keys = None
our_server_keys = self._system_host_keys.get(server_hostkey_name)
if our_server_keys is None:
our_server_keys = self._host_keys.get(server_hostkey_name)
if our_server_keys is not None:
keytype = our_server_keys.keys()[0]
sec_opts = t.get_security_options()
other_types = [x for x in sec_opts.key_types if x != keytype]
sec_opts.key_types = [keytype] + other_types
t.start_client(timeout=timeout)
# If GSS-API Key Exchange is performed we are not required to check the
# host key, because the host is authenticated via GSS-API / SSPI as
# well as our client.
if not self._transport.gss_kex_used:
server_key = t.get_remote_server_key()
if our_server_keys is None:
# will raise exception if the key is rejected
self._policy.missing_host_key(self, server_hostkey_name,
server_key)
else:
our_key = our_server_keys.get(server_key.get_name())
if our_key != server_key:
if our_key is None:
our_key = list(our_server_keys.values())[0]
raise BadHostKeyException(hostname, server_key, our_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif isinstance(key_filename, string_types):
key_filenames = [key_filename]
else:
key_filenames = key_filename
self._auth(
username,
password,
pkey,
key_filenames,
allow_agent,
look_for_keys,
gss_auth,
gss_kex,
gss_deleg_creds,
t.gss_host,
)
def close(self):
"""
Close this SSHClient and its underlying `.Transport`.
.. warning::
Failure to do this may, in some situations, cause your Python
interpreter to hang at shutdown (often due to race conditions).
It's good practice to `close` your client objects anytime you're
done using them, instead of relying on garbage collection.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent is not None:
self._agent.close()
self._agent = None
def exec_command(
self,
command,
bufsize=-1,
timeout=None,
get_pty=False,
environment=None,
):
"""
Execute a command on the SSH server. A new `.Channel` is opened and
the requested command is executed. The command's input and output
streams are returned as Python ``file``-like objects representing
stdin, stdout, and stderr.
:param str command: the command to execute
:param int bufsize:
interpreted the same way as by the built-in ``file()`` function in
Python
:param int timeout:
set command's channel timeout. See `.Channel.settimeout`
:param dict environment:
a dict of shell environment variables, to be merged into the
default environment that the remote command executes within.
.. warning::
Servers may silently reject some environment variables; see the
warning in `.Channel.set_environment_variable` for details.
:return:
the stdin, stdout, and stderr of the executing command, as a
3-tuple
:raises: `.SSHException` -- if the server fails to execute the command
"""
chan = self._transport.open_session(timeout=timeout)
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
if environment:
chan.update_environment(environment)
chan.exec_command(command)
stdin = chan.makefile('wb', bufsize)
stdout = chan.makefile('r', bufsize)
stderr = chan.makefile_stderr('r', bufsize)
return stdin, stdout, stderr
def invoke_shell(self,
term='vt100',
width=80,
height=24,
width_pixels=0,
height_pixels=0,
environment=None):
"""
Start an interactive shell session on the SSH server. A new `.Channel`
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
:param str term:
the terminal type to emulate (for example, ``"vt100"``)
:param int width: the width (in characters) of the terminal window
:param int height: the height (in characters) of the terminal window
:param int width_pixels: the width (in pixels) of the terminal window
:param int height_pixels: the height (in pixels) of the terminal window
:param dict environment: the command's environment
:return: a new `.Channel` connected to the remote shell
:raises: `.SSHException` -- if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
:return: a new `.SFTPClient` session object
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying `.Transport` object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
:return: the `.Transport` for this connection
"""
return self._transport
def _key_from_filepath(self, filename, klass, password):
"""
Attempt to derive a `.PKey` from given string path ``filename``:
- If ``filename`` appears to be a cert, the matching private key is
loaded.
- Otherwise, the filename is assumed to be a private key, and the
matching public cert will be loaded if it exists.
"""
cert_suffix = '-cert.pub'
# Assume privkey, not cert, by default
if filename.endswith(cert_suffix):
key_path = filename[:-len(cert_suffix)]
cert_path = filename
else:
key_path = filename
cert_path = filename + cert_suffix
# Blindly try the key path; if no private key, nothing will work.
key = klass.from_private_key_file(key_path, password)
# TODO: change this to 'Loading' instead of 'Trying' sometime; probably
# when #387 is released, since this is a critical log message users are
# likely testing/filtering for (bah.)
msg = "Trying discovered key {0} in {1}".format(
hexlify(key.get_fingerprint()),
key_path,
)
self._log(DEBUG, msg)
# Attempt to load cert if it exists.
if os.path.isfile(cert_path):
key.load_certificate(cert_path)
self._log(DEBUG, "Adding public certificate {0}".format(cert_path))
return key
def _auth(self, username, password, pkey, key_filenames, allow_agent,
look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host):
"""
Try, in order:
- The key(s) passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa", "id_dsa" or "id_ecdsa" key discoverable in ~/.ssh/
(if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = set()
two_factor_types = set(['keyboard-interactive', 'password'])
# If GSS-API support and GSS-PI Key Exchange was performed, we attempt
# authentication with gssapi-keyex.
if gss_kex and self._transport.gss_kex_used:
try:
self._transport.auth_gssapi_keyex(username)
return
except Exception as e:
saved_exception = e
# Try GSS-API authentication (gssapi-with-mic) only if GSS-API Key
# Exchange is not performed, because if we use GSS-API for the key
# exchange, there is already a fully established GSS-API context, so
# why should we do that again?
if gss_auth:
try:
return self._transport.auth_gssapi_with_mic(
username,
gss_host,
gss_deleg_creds,
)
except Exception as e:
saved_exception = e
if pkey is not None:
try:
self._log(
DEBUG,
'Trying SSH key %s' % hexlify(pkey.get_fingerprint()))
allowed_types = set(
self._transport.auth_publickey(username, pkey))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
except SSHException as e:
saved_exception = e
if not two_factor:
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey, ECDSAKey, Ed25519Key):
try:
key = self._key_from_filepath(
key_filename,
pkey_class,
password,
)
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor and allow_agent:
if self._agent is None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(
DEBUG, 'Trying SSH agent key %s' %
hexlify(key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key password
# will return an allowed 2fac auth method
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor:
keyfiles = []
for keytype, name in [
(RSAKey, "rsa"),
(DSSKey, "dsa"),
(ECDSAKey, "ecdsa"),
(Ed25519Key, "ed25519"),
]:
# ~/ssh/ is for windows
for directory in [".ssh", "ssh"]:
full_path = os.path.expanduser("~/%s/id_%s" %
(directory, name))
if os.path.isfile(full_path):
# TODO: only do this append if below did not run
keyfiles.append((keytype, full_path))
if os.path.isfile(full_path + '-cert.pub'):
keyfiles.append((keytype, full_path + '-cert.pub'))
if not look_for_keys:
keyfiles = []
for pkey_class, filename in keyfiles:
try:
key = self._key_from_filepath(
filename,
pkey_class,
password,
)
# for 2-factor auth a successfully auth'd key will result
# in ['password']
allowed_types = set(
self._transport.auth_publickey(username, key))
two_factor = (allowed_types & two_factor_types)
if not two_factor:
return
break
except (SSHException, IOError) as e:
saved_exception = e
if password is not None:
try:
self._transport.auth_password(username, password)
return
except SSHException as e:
saved_exception = e
elif two_factor:
try:
self._transport.auth_interactive_dumb(username)
return
except SSHException as e:
saved_exception = e
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException('No authentication methods available')
def _log(self, level, msg):
self._transport._log(level, msg)
class SSHClient(object):
"""
A high-level representation of a session with an SSH server. This class
wraps L{Transport}, L{Channel}, and L{SFTPClient} to take care of most
aspects of authenticating and opening channels. A typical use case is::
client = SSHClient()
client.load_system_host_keys()
client.connect('ssh.example.com')
stdin, stdout, stderr = client.exec_command('ls -l')
You may pass in explicit overrides for authentication and server host key
checking. The default mechanism is to try to use local key files or an
SSH agent (if one is running).
@since: 1.6
"""
def __init__(self):
"""
Create a new SSHClient.
"""
self._system_host_keys = HostKeys()
self._host_keys = HostKeys()
self._host_keys_filename = None
self._log_channel = None
self._policy = RejectPolicy()
self._transport = None
self._agent = None
def load_system_host_keys(self, filename=None):
"""
Load host keys from a system (read-only) file. Host keys read with
this method will not be saved back by L{save_host_keys}.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts).
If C{filename} is left as C{None}, an attempt will be made to read
keys from the user's local "known hosts" file, as used by OpenSSH,
and no exception will be raised if the file can't be read. This is
probably only useful on posix.
@param filename: the filename to read, or C{None}
@type filename: str
@raise IOError: if a filename was provided and the file could not be
read
"""
if filename is None:
# try the user's .ssh key file, and mask exceptions
filename = os.path.expanduser("~/.ssh/known_hosts")
try:
self._system_host_keys.load(filename)
except IOError:
pass
return
self._system_host_keys.load(filename)
def load_host_keys(self, filename):
"""
Load host keys from a local host-key file. Host keys read with this
method will be checked I{after} keys loaded via L{load_system_host_keys},
but will be saved back by L{save_host_keys} (so they can be modified).
The missing host key policy L{AutoAddPolicy} adds keys to this set and
saves them, when connecting to a previously-unknown server.
This method can be called multiple times. Each new set of host keys
will be merged with the existing set (new replacing old if there are
conflicts). When automatically saving, the last hostname is used.
@param filename: the filename to read
@type filename: str
@raise IOError: if the filename could not be read
"""
self._host_keys_filename = filename
self._host_keys.load(filename)
def save_host_keys(self, filename):
"""
Save the host keys back to a file. Only the host keys loaded with
L{load_host_keys} (plus any added directly) will be saved -- not any
host keys loaded with L{load_system_host_keys}.
@param filename: the filename to save to
@type filename: str
@raise IOError: if the file could not be written
"""
# update local host keys from file (in case other SSH clients
# have written to the known_hosts file meanwhile.
if self.known_hosts is not None:
self.load_host_keys(self.known_hosts)
f = open(filename, "w")
for hostname, keys in self._host_keys.items():
for keytype, key in keys.items():
f.write("%s %s %s\n" % (hostname, keytype, key.get_base64()))
f.close()
def get_host_keys(self):
"""
Get the local L{HostKeys} object. This can be used to examine the
local host keys or change them.
@return: the local host keys
@rtype: L{HostKeys}
"""
return self._host_keys
def set_log_channel(self, name):
"""
Set the channel for logging. The default is C{"paramiko.transport"}
but it can be set to anything you want.
@param name: new channel name for logging
@type name: str
"""
self._log_channel = name
def set_missing_host_key_policy(self, policy):
"""
Set the policy to use when connecting to a server that doesn't have a
host key in either the system or local L{HostKeys} objects. The
default policy is to reject all unknown servers (using L{RejectPolicy}).
You may substitute L{AutoAddPolicy} or write your own policy class.
@param policy: the policy to use when receiving a host key from a
previously-unknown server
@type policy: L{MissingHostKeyPolicy}
"""
self._policy = policy
def connect(
self,
hostname,
port=SSH_PORT,
username=None,
password=None,
pkey=None,
key_filename=None,
timeout=None,
allow_agent=True,
look_for_keys=True,
compress=False,
sock=None,
):
"""
Connect to an SSH server and authenticate to it. The server's host key
is checked against the system host keys (see L{load_system_host_keys})
and any local host keys (L{load_host_keys}). If the server's hostname
is not found in either set of host keys, the missing host key policy
is used (see L{set_missing_host_key_policy}). The default policy is
to reject the key and raise an L{SSHException}.
Authentication is attempted in the following order of priority:
- The C{pkey} or C{key_filename} passed in (if any)
- Any key we can find through an SSH agent
- Any "id_rsa" or "id_dsa" key discoverable in C{~/.ssh/}
- Plain username/password auth, if a password was given
If a private key requires a password to unlock it, and a password is
passed in, that password will be used to attempt to unlock the key.
@param hostname: the server to connect to
@type hostname: str
@param port: the server port to connect to
@type port: int
@param username: the username to authenticate as (defaults to the
current local username)
@type username: str
@param password: a password to use for authentication or for unlocking
a private key
@type password: str
@param pkey: an optional private key to use for authentication
@type pkey: L{PKey}
@param key_filename: the filename, or list of filenames, of optional
private key(s) to try for authentication
@type key_filename: str or list(str)
@param timeout: an optional timeout (in seconds) for the TCP connect
@type timeout: float
@param allow_agent: set to False to disable connecting to the SSH agent
@type allow_agent: bool
@param look_for_keys: set to False to disable searching for discoverable
private key files in C{~/.ssh/}
@type look_for_keys: bool
@param compress: set to True to turn on compression
@type compress: bool
@param sock: an open socket or socket-like object (such as a
L{Channel}) to use for communication to the target host
@type sock: socket
@raise BadHostKeyException: if the server's host key could not be
verified
@raise AuthenticationException: if authentication failed
@raise SSHException: if there was any other error connecting or
establishing an SSH session
@raise socket.error: if a socket error occurred while connecting
"""
if not sock:
for (family, socktype, proto, canonname, sockaddr) in socket.getaddrinfo(
hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM
):
if socktype == socket.SOCK_STREAM:
af = family
addr = sockaddr
break
else:
# some OS like AIX don't indicate SOCK_STREAM support, so just guess. :(
af, _, _, _, addr = socket.getaddrinfo(hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM)
sock = socket.socket(af, socket.SOCK_STREAM)
if timeout is not None:
try:
sock.settimeout(timeout)
except:
pass
retry_on_signal(lambda: sock.connect(addr))
t = self._transport = Transport(sock)
t.use_compression(compress=compress)
if self._log_channel is not None:
t.set_log_channel(self._log_channel)
t.start_client()
ResourceManager.register(self, t)
server_key = t.get_remote_server_key()
keytype = server_key.get_name()
if port == SSH_PORT:
server_hostkey_name = hostname
else:
server_hostkey_name = "[%s]:%d" % (hostname, port)
our_server_key = self._system_host_keys.get(server_hostkey_name, {}).get(keytype, None)
if our_server_key is None:
our_server_key = self._host_keys.get(server_hostkey_name, {}).get(keytype, None)
if our_server_key is None:
# will raise exception if the key is rejected; let that fall out
self._policy.missing_host_key(self, server_hostkey_name, server_key)
# if the callback returns, assume the key is ok
our_server_key = server_key
if server_key != our_server_key:
raise BadHostKeyException(hostname, server_key, our_server_key)
if username is None:
username = getpass.getuser()
if key_filename is None:
key_filenames = []
elif type(key_filename) == str:
key_filenames = [key_filename]
else:
key_filenames = key_filename
self._auth(username, password, pkey, key_filenames, allow_agent, look_for_keys)
def close(self):
"""
Close this SSHClient and its underlying L{Transport}.
"""
if self._transport is None:
return
self._transport.close()
self._transport = None
if self._agent != None:
self._agent.close()
self._agent = None
def exec_command(self, command, bufsize=-1, timeout=None, get_pty=False):
"""
Execute a command on the SSH server. A new L{Channel} is opened and
the requested command is executed. The command's input and output
streams are returned as python C{file}-like objects representing
stdin, stdout, and stderr.
@param command: the command to execute
@type command: str
@param bufsize: interpreted the same way as by the built-in C{file()} function in python
@type bufsize: int
@param timeout: set command's channel timeout. See L{Channel.settimeout}.settimeout
@type timeout: int
@return: the stdin, stdout, and stderr of the executing command
@rtype: tuple(L{ChannelFile}, L{ChannelFile}, L{ChannelFile})
@raise SSHException: if the server fails to execute the command
"""
chan = self._transport.open_session()
if get_pty:
chan.get_pty()
chan.settimeout(timeout)
chan.exec_command(command)
stdin = chan.makefile("wb", bufsize)
stdout = chan.makefile("rb", bufsize)
stderr = chan.makefile_stderr("rb", bufsize)
return stdin, stdout, stderr
def invoke_shell(self, term=b"vt100", width=80, height=24, width_pixels=0, height_pixels=0):
"""
Start an interactive shell session on the SSH server. A new L{Channel}
is opened and connected to a pseudo-terminal using the requested
terminal type and size.
@param term: the terminal type to emulate (for example, C{"vt100"})
@type term: str
@param width: the width (in characters) of the terminal window
@type width: int
@param height: the height (in characters) of the terminal window
@type height: int
@param width_pixels: the width (in pixels) of the terminal window
@type width_pixels: int
@param height_pixels: the height (in pixels) of the terminal window
@type height_pixels: int
@return: a new channel connected to the remote shell
@rtype: L{Channel}
@raise SSHException: if the server fails to invoke a shell
"""
chan = self._transport.open_session()
chan.get_pty(term, width, height, width_pixels, height_pixels)
chan.invoke_shell()
return chan
def open_sftp(self):
"""
Open an SFTP session on the SSH server.
@return: a new SFTP session object
@rtype: L{SFTPClient}
"""
return self._transport.open_sftp_client()
def get_transport(self):
"""
Return the underlying L{Transport} object for this SSH connection.
This can be used to perform lower-level tasks, like opening specific
kinds of channels.
@return: the Transport for this connection
@rtype: L{Transport}
"""
return self._transport
def _auth(self, username, password, pkey, key_filenames, allow_agent, look_for_keys):
"""
Try, in order:
- The key passed in, if one was passed in.
- Any key we can find through an SSH agent (if allowed).
- Any "id_rsa" or "id_dsa" key discoverable in ~/.ssh/ (if allowed).
- Plain username/password auth, if a password was given.
(The password might be needed to unlock a private key, or for
two-factor authentication [for which it is required].)
"""
saved_exception = None
two_factor = False
allowed_types = []
if pkey is not None:
try:
self._log(DEBUG, "Trying SSH key %s" % hexlify(pkey.get_fingerprint()))
allowed_types = self._transport.auth_publickey(username, pkey)
two_factor = allowed_types == [b"password"]
if not two_factor:
return
except SSHException as e:
saved_exception = e
if not two_factor:
for key_filename in key_filenames:
for pkey_class in (RSAKey, DSSKey):
try:
key = pkey_class.from_private_key_file(key_filename, password)
self._log(DEBUG, "Trying key %s from %s" % (hexlify(key.get_fingerprint()), key_filename))
self._transport.auth_publickey(username, key)
two_factor = allowed_types == [b"password"]
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor and allow_agent:
if self._agent == None:
self._agent = Agent()
for key in self._agent.get_keys():
try:
self._log(DEBUG, "Trying SSH agent key %s" % hexlify(key.get_fingerprint()))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(username, key)
two_factor = allowed_types == [b"password"]
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
if not two_factor:
keyfiles = []
rsa_key = os.path.expanduser("~/.ssh/id_rsa")
dsa_key = os.path.expanduser("~/.ssh/id_dsa")
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
# look in ~/ssh/ for windows users:
rsa_key = os.path.expanduser("~/ssh/id_rsa")
dsa_key = os.path.expanduser("~/ssh/id_dsa")
if os.path.isfile(rsa_key):
keyfiles.append((RSAKey, rsa_key))
if os.path.isfile(dsa_key):
keyfiles.append((DSSKey, dsa_key))
if not look_for_keys:
keyfiles = []
for pkey_class, filename in keyfiles:
try:
key = pkey_class.from_private_key_file(filename, password)
self._log(DEBUG, "Trying discovered key %s in %s" % (hexlify(key.get_fingerprint()), filename))
# for 2-factor auth a successfully auth'd key will result in ['password']
allowed_types = self._transport.auth_publickey(username, key)
two_factor = allowed_types == [b"password"]
if not two_factor:
return
break
except SSHException as e:
saved_exception = e
except IOError as e:
saved_exception = e
if password is not None:
try:
self._transport.auth_password(username, password)
return
except SSHException as e:
saved_exception = e
elif two_factor:
raise SSHException("Two-factor authentication requires a password")
# if we got an auth-failed exception earlier, re-raise it
if saved_exception is not None:
raise saved_exception
raise SSHException("No authentication methods available")
def _log(self, level, msg):
self._transport._log(level, msg)
