def flush_systemd_dns_cache():
# If the user is using systemd-resolve for DNS resolution, it is
# possible for the request to go through systemd-resolve before we
# see it...and it may use a cached result instead of sending a
# request that we can intercept. When sshuttle starts and stops,
# this means that we should clear the cache!
#
# The command to do this was named systemd-resolve, but changed to
# resolvectl in systemd 239.
# https://github.com/systemd/systemd/blob/f8eb41003df1a4eab59ff9bec67b2787c9368dbd/NEWS#L3816
p = None
if helpers.which("resolvectl"):
debug2("Flushing systemd's DNS resolver cache: "
"resolvectl flush-caches")
p = ssubprocess.Popen(["resolvectl", "flush-caches"],
stdout=ssubprocess.PIPE, env=helpers.get_env())
elif helpers.which("systemd-resolve"):
debug2("Flushing systemd's DNS resolver cache: "
"systemd-resolve --flush-caches")
p = ssubprocess.Popen(["systemd-resolve", "--flush-caches"],
stdout=ssubprocess.PIPE, env=helpers.get_env())
if p:
# Wait so flush is finished and process doesn't show up as defunct.
rv = p.wait()
if rv != 0:
log("Received non-zero return code %d when flushing DNS resolver "
"cache." % rv)
def list_routes():
if which('ip'):
routes = _list_routes(['ip', 'route'], _route_iproute)
elif which('netstat'):
routes = _list_routes(['netstat', '-rn'], _route_netstat)
else:
log('WARNING: Neither "ip" nor "netstat" were found on the server. '
'--auto-nets feature will not work.')
routes = []
for (family, ip, width) in routes:
if not ip.startswith('0.') and not ip.startswith('127.'):
yield (family, ip, width)
def get_auto_method():
if which('iptables'):
method_name = "nat"
elif which('nft'):
method_name = "nft"
elif which('pfctl'):
method_name = "pf"
elif which('ipfw'):
method_name = "ipfw"
else:
raise Fatal(
"can't find either iptables, nft or pfctl; check your PATH")
return get_method(method_name)
def __init__(self, method_name, sudo_pythonpath):
self.auto_nets = []
argvbase = ([sys.executable, sys.argv[0]] + ['-v'] *
(helpers.verbose or 0) + ['--method', method_name] +
['--firewall'])
if ssyslog._p:
argvbase += ['--syslog']
# Determine how to prefix the command in order to elevate privileges.
if platform.platform().startswith('OpenBSD'):
elev_prefix = ['doas'] # OpenBSD uses built in `doas`
else:
elev_prefix = ['sudo', '-p', '[local sudo] Password: '******'/usr/bin/env',
'PYTHONPATH=%s' % os.path.dirname(os.path.dirname(__file__))
]
argv_tries = [elev_prefix + argvbase, argvbase]
# we can't use stdin/stdout=subprocess.PIPE here, as we normally would,
# because stupid Linux 'su' requires that stdin be attached to a tty.
# Instead, attach a *bidirectional* socket to its stdout, and use
# that for talking in both directions.
(s1, s2) = socket.socketpair()
def setup():
# run in the child process
s2.close()
if os.getuid() == 0:
argv_tries = argv_tries[-1:] # last entry only
for argv in argv_tries:
try:
if argv[0] == 'su':
sys.stderr.write('[local su] ')
self.p = ssubprocess.Popen(argv, stdout=s1, preexec_fn=setup)
# No env: Talking to `FirewallClient.start`, which has no i18n.
break
except OSError as e:
log('Spawning firewall manager: %r' % argv)
raise Fatal(e)
self.argv = argv
s1.close()
self.pfile = s2.makefile('rwb')
line = self.pfile.readline()
self.check()
if line[0:5] != b'READY':
raise Fatal('%r expected READY, got %r' % (self.argv, line))
method_name = line[6:-1]
self.method = get_method(method_name.decode("ASCII"))
self.method.set_firewall(self)
def flush_systemd_dns_cache():
# If the user is using systemd-resolve for DNS resolution, it is
# possible for the request to go through systemd-resolve before we
# see it...and it may use a cached result instead of sending a
# request that we can intercept. When sshuttle starts and stops,
# this means that we should clear the cache!
#
# The command to do this was named systemd-resolve, but changed to
# resolvectl in systemd 239.
# https://github.com/systemd/systemd/blob/f8eb41003df1a4eab59ff9bec67b2787c9368dbd/NEWS#L3816
if helpers.which("resolvectl"):
debug2("Flushing systemd's DNS resolver cache: "
"resolvectl flush-caches")
ssubprocess.Popen(["resolvectl", "flush-caches"],
stdout=ssubprocess.PIPE, env=helpers.get_env())
elif helpers.which("systemd-resolve"):
debug2("Flushing systemd's DNS resolver cache: "
"systemd-resolve --flush-caches")
ssubprocess.Popen(["systemd-resolve", "--flush-caches"],
stdout=ssubprocess.PIPE, env=helpers.get_env())
def is_supported(self):
if which("ipfw"):
return True
debug2("ipfw method not supported because 'ipfw' command is "
"missing.")
return False
def connect(ssh_cmd, rhostport, python, stderr, options):
username, password, port, host = parse_hostport(rhostport)
if username:
rhost = "{}@{}".format(username, host)
else:
rhost = host
z = zlib.compressobj(1)
content = get_module_source('sshuttle.assembler')
optdata = ''.join("%s=%r\n" % (k, v) for (k, v) in list(options.items()))
optdata = optdata.encode("UTF8")
content2 = (empackage(z, 'sshuttle') +
empackage(z, 'sshuttle.cmdline_options', optdata) +
empackage(z, 'sshuttle.helpers') +
empackage(z, 'sshuttle.ssnet') +
empackage(z, 'sshuttle.hostwatch') +
empackage(z, 'sshuttle.server') + b"\n")
pyscript = r"""
import sys, os;
verbosity=%d;
sys.stdin = os.fdopen(0, "rb");
exec(compile(sys.stdin.read(%d), "assembler.py", "exec"))
""" % (helpers.verbose or 0, len(content))
pyscript = re.sub(r'\s+', ' ', pyscript.strip())
if not rhost:
# ignore the --python argument when running locally; we already know
# which python version works.
argv = [sys.executable, '-c', pyscript]
else:
if ssh_cmd:
sshl = shlex.split(ssh_cmd)
else:
sshl = ['ssh']
if port is not None:
portl = ["-p", str(port)]
else:
portl = []
if python:
pycmd = "'%s' -c '%s'" % (python, pyscript)
else:
pycmd = ("P=python3; $P -V 2>%s || P=python; "
"exec \"$P\" -c %s") % (os.devnull, quote(pyscript))
pycmd = ("/bin/sh -c {}".format(quote(pycmd)))
if password is not None:
os.environ['SSHPASS'] = str(password)
argv = (["sshpass", "-e"] + sshl + portl + [rhost, '--', pycmd])
else:
argv = (sshl + portl + [rhost, '--', pycmd])
# Our which() function searches for programs in get_path()
# directories (which include PATH). This step isn't strictly
# necessary if ssh is already in the user's PATH, but it makes the
# error message friendlier if the user incorrectly passes in a
# custom ssh command that we cannot find.
abs_path = which(argv[0])
if abs_path is None:
raise Fatal("Failed to find '%s' in path %s" % (argv[0], get_path()))
argv[0] = abs_path
(s1, s2) = socket.socketpair()
def setup():
# runs in the child process
s2.close()
s1a, s1b = os.dup(s1.fileno()), os.dup(s1.fileno())
s1.close()
debug2('executing: %r\n' % argv)
p = ssubprocess.Popen(argv,
stdin=s1a,
stdout=s1b,
preexec_fn=setup,
close_fds=True,
stderr=stderr)
os.close(s1a)
os.close(s1b)
s2.sendall(content)
s2.sendall(content2)
return p, s2
def is_supported(self):
if which("nft"):
return True
debug2("nft method not supported because 'nft' command is missing.")
return False
def is_supported(self):
if which("iptables"):
return True
debug2("nat method not supported because 'iptables' command "
"is missing.")
return False
def is_supported(self):
if which("iptables") and which("ip6tables"):
return True
debug2("tproxy method not supported because 'iptables' "
"or 'ip6tables' commands are missing.\n")
return False
def connect(ssh_cmd, rhostport, python, stderr, options):
username, password, port, host = parse_hostport(rhostport)
if username:
rhost = "{}@{}".format(username, host)
else:
rhost = host
z = zlib.compressobj(1)
content = get_module_source('sshuttle.assembler')
optdata = ''.join("%s=%r\n" % (k, v) for (k, v) in list(options.items()))
optdata = optdata.encode("UTF8")
content2 = (empackage(z, 'sshuttle') +
empackage(z, 'sshuttle.cmdline_options', optdata) +
empackage(z, 'sshuttle.helpers') +
empackage(z, 'sshuttle.ssnet') +
empackage(z, 'sshuttle.hostwatch') +
empackage(z, 'sshuttle.server') + b"\n")
# If the exec() program calls sys.exit(), it should exit python
# and the sys.exit(98) call won't be reached (so we try to only
# exit that way in the server). However, if the code that we
# exec() simply returns from main, then we will return from
# exec(). If the server's python process dies, it should stop
# executing and also won't reach sys.exit(98).
#
# So, we shouldn't reach sys.exit(98) and we certainly shouldn't
# reach it immediately after trying to start the server.
pyscript = r"""
import sys, os;
verbosity=%d;
sys.stdin = os.fdopen(0, "rb");
exec(compile(sys.stdin.read(%d), "assembler.py", "exec"));
sys.exit(98);
""" % (helpers.verbose or 0, len(content))
pyscript = re.sub(r'\s+', ' ', pyscript.strip())
if not rhost:
# ignore the --python argument when running locally; we already know
# which python version works.
argv = [sys.executable, '-c', pyscript]
else:
if ssh_cmd:
sshl = shlex.split(ssh_cmd)
else:
sshl = ['ssh']
if port is not None:
portl = ["-p", str(port)]
else:
portl = []
if python:
pycmd = "'%s' -c '%s'" % (python, pyscript)
else:
# By default, we run the following code in a shell.
# However, with restricted shells and other unusual
# situations, there can be trouble. See the RESTRICTED
# SHELL section in "man bash" for more information. The
# code makes many assumptions:
#
# (1) That /bin/sh exists and that we can call it.
# Restricted shells often do *not* allow you to run
# programs specified with an absolute path like /bin/sh.
# Either way, if there is trouble with this, it should
# return error code 127.
#
# (2) python3 or python exists in the PATH and is
# executable. If they aren't, then exec won't work (see (4)
# below).
#
# (3) In /bin/sh, that we can redirect stderr in order to
# hide the version that "python3 -V" might print (some
# restricted shells don't allow redirection, see
# RESTRICTED SHELL section in 'man bash'). However, if we
# are in a restricted shell, we'd likely have trouble with
# assumption (1) above.
#
# (4) The 'exec' command should work except if we failed
# to exec python because it doesn't exist or isn't
# executable OR if exec isn't allowed (some restricted
# shells don't allow exec). If the exec succeeded, it will
# not return and not get to the "exit 97" command. If exec
# does return, we exit with code 97.
#
# Specifying the exact python program to run with --python
# avoids many of the issues above. However, if
# you have a restricted shell on remote, you may only be
# able to run python if it is in your PATH (and you can't
# run programs specified with an absolute path). In that
# case, sshuttle might not work at all since it is not
# possible to run python on the remote machine---even if
# it is present.
pycmd = ("P=python3; $P -V 2>%s || P=python; "
"exec \"$P\" -c %s; exit 97") % \
(os.devnull, quote(pyscript))
pycmd = ("/bin/sh -c {}".format(quote(pycmd)))
if password is not None:
os.environ['SSHPASS'] = str(password)
argv = (["sshpass", "-e"] + sshl + portl + [rhost, '--', pycmd])
else:
argv = (sshl + portl + [rhost, '--', pycmd])
# Our which() function searches for programs in get_path()
# directories (which include PATH). This step isn't strictly
# necessary if ssh is already in the user's PATH, but it makes the
# error message friendlier if the user incorrectly passes in a
# custom ssh command that we cannot find.
abs_path = which(argv[0])
if abs_path is None:
raise Fatal("Failed to find '%s' in path %s" % (argv[0], get_path()))
argv[0] = abs_path
(s1, s2) = socket.socketpair()
def setup():
# runs in the child process
s2.close()
s1a, s1b = os.dup(s1.fileno()), os.dup(s1.fileno())
s1.close()
debug2('executing: %r' % argv)
p = ssubprocess.Popen(argv,
stdin=s1a,
stdout=s1b,
preexec_fn=setup,
close_fds=True,
stderr=stderr)
os.close(s1a)
os.close(s1b)
s2.sendall(content)
s2.sendall(content2)
return p, s2
def is_supported(self):
if which("pfctl"):
return True
debug2("pf method not supported because 'pfctl' command is missing.")
return False