Merge pull request #550 from skuhl/nft-ipv6

IPv6 support in nft method.

docs/manpage.rst

@@ -37,14 +37,18 @@ Options
     netmask), and 0/0 ('just route everything through the
     VPN'). Any of the previous examples are also valid if you append
     a port or a port range, so 1.2.3.4:8000 will only tunnel traffic
-    that has as the destination port 8000 of 1.2.3.4 and 
+    that has as the destination port 8000 of 1.2.3.4 and
     1.2.3.0/24:8000-9000 will tunnel traffic going to any port between
     8000 and 9000 (inclusive) for all IPs in the 1.2.3.0/24 subnet.
-    It is also possible to use a name in which case the first IP it resolves
-    to during startup will be routed over the VPN. Valid examples are
-    example.com, example.com:8000 and example.com:8000-9000.
+    A hostname can be provided instead of an IP address. If the
+    hostname resolves to multiple IPs, all of the IPs are included.
+    If a width is provided with a hostname that the width is applied
+    to all of the hostnames IPs (if they are all either IPv4 or IPv6).
+    Widths cannot be supplied to hostnames that resolve to both IPv4
+    and IPv6. Valid examples are example.com, example.com:8000,
+    example.com/24, example.com/24:8000 and example.com:8000-9000.
 
-.. option:: --method <auto|nat|nft|tproxy|pf>
+.. option:: --method <auto|nat|nft|tproxy|pf|ipfw>
 
    Which firewall method should sshuttle use? For auto, sshuttle attempts to
    guess the appropriate method depending on what it can find in PATH. The
@@ -64,9 +68,9 @@ Options
     You can use any name resolving to an IP address of the machine running
     :program:`sshuttle`, e.g. ``--listen localhost``.
 
-    For the tproxy and pf methods this can be an IPv6 address. Use this option 
-    with comma separated values if required, to provide both IPv4 and IPv6
-    addresses, e.g. ``--listen 127.0.0.1:0,[::1]:0``.
+    For the nft, tproxy and pf methods this can be an IPv6 address. Use 
+    this option with comma separated values if required, to provide both 
+    IPv4 and IPv6 addresses, e.g. ``--listen 127.0.0.1:0,[::1]:0``.
 
 .. option:: -H, --auto-hosts
 
@@ -92,6 +96,10 @@ Options
     are taken automatically from the server's routing
     table.
 
+    This feature does not detect IPv6 routes. Specify IPv6 subnets
+    manually. For example, specify the ``::/0`` subnet on the command
+    line to route all IPv6 traffic.
+
 .. option:: --dns
 
     Capture local DNS requests and forward to the remote DNS
@@ -122,9 +130,9 @@ Options
 
 .. option:: --python
 
-    Specify the name/path of the remote python interpreter.
-    The default is just ``python``, which means to use the
-    default python interpreter on the remote system's PATH.
+    Specify the name/path of the remote python interpreter. The
+    default is to use ``python3`` (or ``python``, if ``python3``
+    fails) in the remote system's PATH.
 
 .. option:: -r <[username@]sshserver[:port]>, --remote=<[username@]sshserver[:port]>
 
@@ -221,7 +229,8 @@ Options
 
 .. option:: --disable-ipv6
 
-    If using tproxy or pf methods, this will disable IPv6 support.
+    Disable IPv6 support for methods that support it (nft, tproxy, and
+    pf).
 
 .. option:: --firewall
 

docs/requirements.rst

@@ -20,6 +20,18 @@ Requires:
 
 * iptables DNAT, REDIRECT, and ttl modules.
 
+Linux with nft method
+~~~~~~~~~~~~~~~~~~~~~
+Supports
+
+* IPv4 TCP
+* IPv4 DNS
+* IPv6 TCP
+* IPv6 DNS
+
+Requires:
+
+* nftables
 
 Linux with TPROXY method
 ~~~~~~~~~~~~~~~~~~~~~~~~

sshuttle/methods/__init__.py

@@ -3,24 +3,34 @@ import importlib
 import socket
 import struct
 import errno
+import ipaddress
 from sshuttle.helpers import Fatal, debug3
 
 
 def original_dst(sock):
+    ip = "0.0.0.0"
+    port = -1
     try:
+        family = sock.family
         SO_ORIGINAL_DST = 80
-        SOCKADDR_MIN = 16
-        sockaddr_in = sock.getsockopt(socket.SOL_IP,
-                                      SO_ORIGINAL_DST, SOCKADDR_MIN)
-        (proto, port, a, b, c, d) = struct.unpack('!HHBBBB', sockaddr_in[:8])
-        # FIXME: decoding is IPv4 only.
-        assert(socket.htons(proto) == socket.AF_INET)
-        ip = '%d.%d.%d.%d' % (a, b, c, d)
-        return (ip, port)
+
+        if family == socket.AF_INET:
+            SOCKADDR_MIN = 16
+            sockaddr_in = sock.getsockopt(socket.SOL_IP,
+                                          SO_ORIGINAL_DST, SOCKADDR_MIN)
+            port, raw_ip = struct.unpack_from('!2xH4s', sockaddr_in[:8])
+            ip = str(ipaddress.IPv4Address(raw_ip))
+        elif family == socket.AF_INET6:
+            sockaddr_in = sock.getsockopt(41, SO_ORIGINAL_DST, 64)
+            port, raw_ip = struct.unpack_from("!2xH4x16s", sockaddr_in)
+            ip = str(ipaddress.IPv6Address(raw_ip))
+        else:
+            raise Fatal("fw: Unknown family type.")
     except socket.error as e:
         if e.args[0] == errno.ENOPROTOOPT:
             return sock.getsockname()
         raise
+    return (ip, port)
 
 
 class Features(object):

sshuttle/methods/nft.py

@@ -16,7 +16,10 @@ class Method(BaseMethod):
         if udp:
             raise Exception("UDP not supported by nft")
 
-        table = 'sshuttle-%s' % port
+        if family == socket.AF_INET:
+            table = 'sshuttle-ipv4-%s' % port
+        if family == socket.AF_INET6:
+            table = 'sshuttle-ipv6-%s' % port
 
         def _nft(action, *args):
             return nft(family, table, action, *args)
@@ -37,7 +40,10 @@ class Method(BaseMethod):
         # This TTL hack allows the client and server to run on the
         # same host. The connections the sshuttle server makes will
         # have TTL set to 63.
-        _nft('add rule', chain, 'ip ttl == 63 return')
+        if family == socket.AF_INET:
+            _nft('add rule', chain, 'ip ttl == 63 return')
+        elif family == socket.AF_INET6:
+            _nft('add rule', chain, 'ip6 hoplimit == 63 return')
 
         # Redirect DNS traffic as requested. This includes routing traffic
         # to localhost DNS servers through sshuttle.
@@ -57,7 +63,11 @@ class Method(BaseMethod):
         # create new subnet entries.
         for _, swidth, sexclude, snet, fport, lport \
                 in sorted(subnets, key=subnet_weight, reverse=True):
-            tcp_ports = ('ip', 'protocol', 'tcp')
+            if family == socket.AF_INET:
+                tcp_ports = ('ip', 'protocol', 'tcp')
+            elif family == socket.AF_INET6:
+                tcp_ports = ('ip6', 'nexthdr', 'tcp')
+
             if fport and fport != lport:
                 tcp_ports = \
                     tcp_ports + \
@@ -66,21 +76,38 @@ class Method(BaseMethod):
                 tcp_ports = tcp_ports + ('tcp', 'dport', '%d' % (fport))
 
             if sexclude:
-                _nft('add rule', chain, *(tcp_ports + (
-                     'ip daddr %s/%s' % (snet, swidth), 'return')))
+                if family == socket.AF_INET:
+                    _nft('add rule', chain, *(tcp_ports + (
+                        'ip daddr %s/%s' % (snet, swidth), 'return')))
+                elif family == socket.AF_INET6:
+                    _nft('add rule', chain, *(tcp_ports + (
+                        'ip6 daddr %s/%s' % (snet, swidth), 'return')))
             else:
-                _nft('add rule', chain, *(tcp_ports + (
-                     'ip daddr %s/%s' % (snet, swidth),
-                     ('redirect to :' + str(port)))))
+                if family == socket.AF_INET:
+                    _nft('add rule', chain, *(tcp_ports + (
+                        'ip daddr %s/%s' % (snet, swidth),
+                        ('redirect to :' + str(port)))))
+                elif family == socket.AF_INET6:
+                    _nft('add rule', chain, *(tcp_ports + (
+                        'ip6 daddr %s/%s' % (snet, swidth),
+                        ('redirect to :' + str(port)))))
 
     def restore_firewall(self, port, family, udp, user):
         if udp:
             raise Exception("UDP not supported by nft method_name")
 
-        table = 'sshuttle-%s' % port
+        if family == socket.AF_INET:
+            table = 'sshuttle-ipv4-%s' % port
+        if family == socket.AF_INET6:
+            table = 'sshuttle-ipv6-%s' % port
 
         def _nft(action, *args):
             return nft(family, table, action, *args)
 
         # basic cleanup/setup of chains
         nonfatal(_nft, 'delete table', '')
+
+    def get_supported_features(self):
+        result = super(Method, self).get_supported_features()
+        result.ipv6 = True
+        return result

tests/client/test_methods_nat.py

@@ -18,12 +18,22 @@ def test_get_supported_features():
 
 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()