def _establish_ssh_session(self):
# Connect to remote host.
try:
sock = socket.create_connection(
(str(self._ssh_host), self._ssh_port))
except Exception:
log.error("Cannot connect to host '%s' (%s, %d).", self.name,
self._ssh_host, self._ssh_port)
raise
# SSH handshake.
ssh_session = Session()
ssh_session.handshake(sock)
# Verify host key. Accept keys from previously unknown hosts on first connection.
hosts = ssh_session.knownhost_init()
testbed_root = os.path.dirname(os.path.abspath(inspect.stack()[-1][1]))
known_hosts_path = os.path.join(testbed_root, KNOWN_HOSTS_FILE)
try:
hosts.readfile(known_hosts_path)
except ssh2.exceptions.KnownHostReadFileError:
pass # ignore, file is created/overwritten later
host_key, key_type = ssh_session.hostkey()
server_type = None
if key_type == LIBSSH2_HOSTKEY_TYPE_RSA:
server_type = LIBSSH2_KNOWNHOST_KEY_SSHRSA
else:
server_type = LIBSSH2_KNOWNHOST_KEY_SSHDSS
type_mask = LIBSSH2_KNOWNHOST_TYPE_PLAIN | LIBSSH2_KNOWNHOST_KEYENC_RAW | server_type
try:
hosts.checkp(
str(self._ssh_host).encode('utf-8'), self._ssh_port, host_key,
type_mask)
except ssh2.exceptions.KnownHostCheckNotFoundError:
log.warn("Host key of '%s' (%s, %d) added to known hosts.",
self.name, self._ssh_host, self._ssh_port)
hosts.addc(
str(self._ssh_host).encode('utf-8'), host_key, type_mask)
hosts.writefile(known_hosts_path)
except ssh2.exceptions.KnownHostCheckMisMatchError:
log.error("Host key of '%s' (%s, %d) does not match known key.",
self.name, self._ssh_host, self._ssh_port)
raise
# Authenticate at remote host.
try:
if self._identity_file is None:
ssh_session.agent_auth(self._username)
else:
ssh_session.userauth_publickey_fromfile(
self._username, self._identity_file)
except Exception:
log.error("Authentication at host '%s' (%s, %d) failed.",
self.name, self._ssh_host, self._ssh_port)
ssh_session.disconnect()
raise
return ssh_session
# Make socket, connect
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((host, 22))
# Initialise
session = Session()
session.handshake(sock)
host_key, key_type = session.hostkey()
server_key_type = LIBSSH2_KNOWNHOST_KEY_SSHRSA \
if key_type == LIBSSH2_HOSTKEY_TYPE_RSA \
else LIBSSH2_KNOWNHOST_KEY_SSHDSS
kh = session.knownhost_init()
_read_hosts = kh.readfile(known_hosts)
print("Read %s hosts from known hosts file at %s" % (_read_hosts, known_hosts))
# Verification
type_mask = LIBSSH2_KNOWNHOST_TYPE_PLAIN | \
LIBSSH2_KNOWNHOST_KEYENC_RAW | \
server_key_type
kh.checkp(host, 22, host_key, type_mask)
print("Host verification passed.")
# Verification passed, continue with authentication
session.agent_auth(user)
channel = session.open_session()
channel.execute('echo me')