sshuttle/tests/client/test_methods_nat.py
Scott Kuhl bc065e368d Remove ttl hack & require -r option.
Previously, it was possible to run sshuttle locally without using ssh
and connecting to a remote server. In this configuration, traffic was
redirected to the sshuttle server running on the localhost. However,
the firewall needed to distinguish between traffic leaving the
sshuttle server and traffic that originated from the machine that
still needed to be routed through the sshuttle server. The TTL of the
packets leaving the sshuttle server were manipulated to indicate to
the firewall what should happen. The TTL was adjusted for all packets
leaving the sshuttle server (even if it wasn't necessary because the
server and client were running on different machines).

Changing the TTL caused trouble and some machines, and
the --ttl option was added as a workaround to change how the TTL was
set for traffic leaving sshuttle. All of this added complexity to the
code for a feature (running the server on localhost) that is likely
only used for testing and rarely used by others.

This commit updates the associated documentation, but doesn't fully
fix the ipfw method since I am unable to test that.

This change will also make sshuttle fail to work if -r is used to
specify a localhost. Pull request #610 partially addresses that issue.

For example, see: #240, #490, #660, #606.
2021-07-12 11:24:29 -04:00

213 lines
7.4 KiB
Python

import socket
from socket import AF_INET, AF_INET6
import struct
import pytest
from unittest.mock import Mock, patch, call
from sshuttle.helpers import Fatal
from sshuttle.methods import get_method
def test_get_supported_features():
method = get_method('nat')
features = method.get_supported_features()
assert features.ipv6
assert not features.udp
assert features.dns
def test_get_tcp_dstip():
sock = Mock()
sock.family = AF_INET
sock.getsockopt.return_value = struct.pack(
'!HHBBBB', socket.ntohs(AF_INET), 1024, 127, 0, 0, 1)
method = get_method('nat')
assert method.get_tcp_dstip(sock) == ('127.0.0.1', 1024)
assert sock.mock_calls == [call.getsockopt(0, 80, 16)]
sock = Mock()
sock.family = AF_INET6
sock.getsockopt.return_value = struct.pack(
'!HH4xBBBBBBBBBBBBBBBB', socket.ntohs(AF_INET6),
1024, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1)
method = get_method('nft')
assert method.get_tcp_dstip(sock) == ('::1', 1024)
assert sock.mock_calls == [call.getsockopt(41, 80, 64)]
def test_recv_udp():
sock = Mock()
sock.recvfrom.return_value = "11111", "127.0.0.1"
method = get_method('nat')
result = method.recv_udp(sock, 1024)
assert sock.mock_calls == [call.recvfrom(1024)]
assert result == ("127.0.0.1", None, "11111")
def test_send_udp():
sock = Mock()
method = get_method('nat')
method.send_udp(sock, None, "127.0.0.1", "22222")
assert sock.mock_calls == [call.sendto("22222", "127.0.0.1")]
def test_setup_tcp_listener():
listener = Mock()
method = get_method('nat')
method.setup_tcp_listener(listener)
assert listener.mock_calls == []
def test_setup_udp_listener():
listener = Mock()
method = get_method('nat')
method.setup_udp_listener(listener)
assert listener.mock_calls == []
def test_assert_features():
method = get_method('nat')
features = method.get_supported_features()
method.assert_features(features)
features.udp = True
with pytest.raises(Fatal):
method.assert_features(features)
features.ipv6 = True
with pytest.raises(Fatal):
method.assert_features(features)
def test_firewall_command():
method = get_method('nat')
assert not method.firewall_command("somthing")
@patch('sshuttle.methods.nat.ipt')
@patch('sshuttle.methods.nat.ipt_chain_exists')
def test_setup_firewall(mock_ipt_chain_exists, mock_ipt):
mock_ipt_chain_exists.return_value = True
method = get_method('nat')
assert method.name == 'nat'
assert mock_ipt_chain_exists.mock_calls == []
assert mock_ipt.mock_calls == []
method.setup_firewall(
1024, 1026,
[(AF_INET6, u'2404:6800:4004:80c::33')],
AF_INET6,
[(AF_INET6, 64, False, u'2404:6800:4004:80c::', 0, 0),
(AF_INET6, 128, True, u'2404:6800:4004:80c::101f', 80, 80)],
False,
None,
'0x01')
assert mock_ipt_chain_exists.mock_calls == [
call(AF_INET6, 'nat', 'sshuttle-1024')
]
assert mock_ipt.mock_calls == [
call(AF_INET6, 'nat', '-D', 'OUTPUT', '-j', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-D', 'PREROUTING', '-j', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-F', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-X', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-N', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-F', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-I', 'OUTPUT', '1', '-j', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-I', 'PREROUTING', '1', '-j', 'sshuttle-1024'),
call(AF_INET6, 'nat', '-A', 'sshuttle-1024', '-j', 'REDIRECT',
'--dest', u'2404:6800:4004:80c::33', '-p', 'udp',
'--dport', '53', '--to-ports', '1026'),
call(AF_INET6, 'nat', '-A', 'sshuttle-1024', '-j', 'RETURN',
'-m', 'addrtype', '--dst-type', 'LOCAL'),
call(AF_INET6, 'nat', '-A', 'sshuttle-1024', '-j', 'RETURN',
'--dest', u'2404:6800:4004:80c::101f/128', '-p', 'tcp',
'--dport', '80:80'),
call(AF_INET6, 'nat', '-A', 'sshuttle-1024', '-j', 'REDIRECT',
'--dest', u'2404:6800:4004:80c::/64', '-p', 'tcp',
'--to-ports', '1024')
]
mock_ipt_chain_exists.reset_mock()
mock_ipt.reset_mock()
assert mock_ipt_chain_exists.mock_calls == []
assert mock_ipt.mock_calls == []
with pytest.raises(Exception) as excinfo:
method.setup_firewall(
1025, 1027,
[(AF_INET, u'1.2.3.33')],
AF_INET,
[(AF_INET, 24, False, u'1.2.3.0', 8000, 9000),
(AF_INET, 32, True, u'1.2.3.66', 8080, 8080)],
True,
None,
'0x01')
assert str(excinfo.value) == 'UDP not supported by nat method_name'
assert mock_ipt_chain_exists.mock_calls == []
assert mock_ipt.mock_calls == []
method.setup_firewall(
1025, 1027,
[(AF_INET, u'1.2.3.33')],
AF_INET,
[(AF_INET, 24, False, u'1.2.3.0', 8000, 9000),
(AF_INET, 32, True, u'1.2.3.66', 8080, 8080)],
False,
None,
'0x01')
assert mock_ipt_chain_exists.mock_calls == [
call(AF_INET, 'nat', 'sshuttle-1025')
]
assert mock_ipt.mock_calls == [
call(AF_INET, 'nat', '-D', 'OUTPUT', '-j', 'sshuttle-1025'),
call(AF_INET, 'nat', '-D', 'PREROUTING', '-j', 'sshuttle-1025'),
call(AF_INET, 'nat', '-F', 'sshuttle-1025'),
call(AF_INET, 'nat', '-X', 'sshuttle-1025'),
call(AF_INET, 'nat', '-N', 'sshuttle-1025'),
call(AF_INET, 'nat', '-F', 'sshuttle-1025'),
call(AF_INET, 'nat', '-I', 'OUTPUT', '1', '-j', 'sshuttle-1025'),
call(AF_INET, 'nat', '-I', 'PREROUTING', '1', '-j', 'sshuttle-1025'),
call(AF_INET, 'nat', '-A', 'sshuttle-1025', '-j', 'REDIRECT',
'--dest', u'1.2.3.33', '-p', 'udp',
'--dport', '53', '--to-ports', '1027'),
call(AF_INET, 'nat', '-A', 'sshuttle-1025', '-j', 'RETURN',
'-m', 'addrtype', '--dst-type', 'LOCAL'),
call(AF_INET, 'nat', '-A', 'sshuttle-1025', '-j', 'RETURN',
'--dest', u'1.2.3.66/32', '-p', 'tcp', '--dport', '8080:8080'),
call(AF_INET, 'nat', '-A', 'sshuttle-1025', '-j', 'REDIRECT',
'--dest', u'1.2.3.0/24', '-p', 'tcp', '--dport', '8000:9000',
'--to-ports', '1025')
]
mock_ipt_chain_exists.reset_mock()
mock_ipt.reset_mock()
method.restore_firewall(1025, AF_INET, False, None)
assert mock_ipt_chain_exists.mock_calls == [
call(AF_INET, 'nat', 'sshuttle-1025')
]
assert mock_ipt.mock_calls == [
call(AF_INET, 'nat', '-D', 'OUTPUT', '-j',
'sshuttle-1025'),
call(AF_INET, 'nat', '-D', 'PREROUTING', '-j',
'sshuttle-1025'),
call(AF_INET, 'nat', '-F', 'sshuttle-1025'),
call(AF_INET, 'nat', '-X', 'sshuttle-1025')
]
mock_ipt_chain_exists.reset_mock()
mock_ipt.reset_mock()
method.restore_firewall(1025, AF_INET6, False, None)
assert mock_ipt_chain_exists.mock_calls == [
call(AF_INET6, 'nat', 'sshuttle-1025')
]
assert mock_ipt.mock_calls == [
call(AF_INET6, 'nat', '-D', 'OUTPUT', '-j', 'sshuttle-1025'),
call(AF_INET6, 'nat', '-D', 'PREROUTING', '-j',
'sshuttle-1025'),
call(AF_INET6, 'nat', '-F', 'sshuttle-1025'),
call(AF_INET6, 'nat', '-X', 'sshuttle-1025')
]
mock_ipt_chain_exists.reset_mock()
mock_ipt.reset_mock()