After having spent now hours troubleshooting, trawling potential solutions on this site and others, and I am resigned to beg the advice of my betters. I am working to route all network traffic on an instance of Ubuntu over a Cisco VPN at a university. Using either the built in network manager or vpnc, I can successfully establish a connection to the VPN, and can successfully route traffic to any university IP over the VPN. However, aside of those specific IP ranges, I cannot seem to conjure any route which will successfully map all network traffic over the VPN.
So far, I've attempted:
route add -net 0.0.0.0 gw homeportal dev tun0
route add -net 0.0.0.0 tun0
route add -net 0.0.0.0 gw 128.122.252.77 dev tun0
route add -net 0.0.0.0 gw 128.122.252.77 dev eth0
iptables -A FORWARD -o tun0 -j ACCEPT
iptables -A FORWARD -i tun0 -j ACCEPT
iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE
And many other silly, ineffective, things that I cannot remember well enough to transcribe accurately.
In addition, I've tried routing smaller IP ranges, and specific IPs, each to no avail. I'm not really sure what's going wrong, as the extent of the effects I've been able to observe are failures of name resolution, and failures to route traffic over the VPN. What am I doing wrong here?
Edit-
Here is the output of ip route show after starting the VPN connection with VPNC:
default via 192.168.1.254 dev eth0 proto static
10.0.0.0/8 dev tun0 scope link
91.230.41.0/24 dev tun0 scope link
128.122.0.0/16 dev tun0 scope link
128.122.252.68 via 192.168.1.254 dev eth0 src 192.168.1.32
128.122.253.46 dev tun0 scope link
128.122.253.79 dev tun0 scope link
172.16.0.0/12 dev tun0 scope link
192.168.0.0/16 dev tun0 scope link
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.32 metric 1
193.175.54.0/24 dev tun0 scope link
193.205.158.0/25 dev tun0 scope link
193.206.104.0/24 dev tun0 scope link
195.113.94.0/24 dev tun0 scope link
203.126.200.0/24 dev tun0 scope link
203.174.165.128/25 dev tun0 scope link
212.219.93.0/24 dev tun0 scope link
216.165.0.0/17 dev tun0 scope link
More information-
I've successfully routed arbitrary traffic over this VPN in MS Windows via the Cisco AnyConnect client with default configuration. Here is what the routing table looks like when the AnyConnect client is working (this is a different computer behind the same router at 192.168.1.254).
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 192.168.1.254 192.168.1.13 30
10.0.0.0 255.0.0.0 192.168.128.1 192.168.128.197 2
91.230.41.0 255.255.255.0 192.168.128.1 192.168.128.197 2
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
128.122.0.0 255.255.0.0 192.168.128.1 192.168.128.197 2
128.122.252.68 255.255.255.255 192.168.1.254 192.168.1.13 31
172.16.0.0 255.240.0.0 192.168.128.1 192.168.128.197 2
192.168.0.0 255.255.0.0 192.168.128.1 192.168.128.197 2
192.168.1.0 255.255.255.0 On-link 192.168.1.13 286
192.168.1.13 255.255.255.255 On-link 192.168.1.13 286
192.168.1.254 255.255.255.255 On-link 192.168.1.13 31
192.168.1.255 255.255.255.255 On-link 192.168.1.13 286
192.168.31.0 255.255.255.0 On-link 192.168.31.1 276
192.168.31.1 255.255.255.255 On-link 192.168.31.1 276
192.168.31.255 255.255.255.255 On-link 192.168.31.1 276
192.168.128.0 255.255.255.0 On-link 192.168.128.197 257
192.168.128.197 255.255.255.255 On-link 192.168.128.197 257
192.168.128.255 255.255.255.255 On-link 192.168.128.197 257
192.168.203.0 255.255.255.0 On-link 192.168.203.1 276
192.168.203.1 255.255.255.255 On-link 192.168.203.1 276
192.168.203.255 255.255.255.255 On-link 192.168.203.1 276
193.175.54.0 255.255.255.0 192.168.128.1 192.168.128.197 2
193.205.158.0 255.255.255.128 192.168.128.1 192.168.128.197 2
193.206.104.0 255.255.255.0 192.168.128.1 192.168.128.197 2
195.113.94.0 255.255.255.0 192.168.128.1 192.168.128.197 2
203.126.200.0 255.255.255.0 192.168.128.1 192.168.128.197 2
203.174.165.128 255.255.255.128 192.168.128.1 192.168.128.197 2
212.219.93.0 255.255.255.0 192.168.128.1 192.168.128.197 2
216.165.0.0 255.255.128.0 192.168.128.1 192.168.128.197 2
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 192.168.1.13 286
224.0.0.0 240.0.0.0 On-link 192.168.203.1 276
224.0.0.0 240.0.0.0 On-link 192.168.31.1 276
224.0.0.0 240.0.0.0 On-link 192.168.128.197 10000
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 192.168.1.13 286
255.255.255.255 255.255.255.255 On-link 192.168.203.1 276
255.255.255.255 255.255.255.255 On-link 192.168.31.1 276
255.255.255.255 255.255.255.255 On-link 192.168.128.197 10000
===========================================================================
Answer
Your local network is 192.168.1.0/24, as shown by this line in your routing table:
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.32 metric 1
Your VPN network is 10.0.0.0/8, as shown by this line:
10.0.0.0/8 dev tun0 scope link
Currently, your default router is:
default via 192.168.1.254 dev eth0 proto static
which is of course what you do not want, because it belongs to your local LAN: thus all of your stuff is routed through your local gateway, as if the VPN did not exist.
You do have however, the all-important statement
128.122.252.68 via 192.168.1.254 dev eth0 src 192.168.1.32
which is the route to your VPN-provider.
EDIT:
I had not realized that the routing table is simply the one that is obtained from your VPN, without your intervention. This may indicate (indirectly) that your service provider is willing to forward only the traffic explicitly allowed in your table through the interface tun0, and may have taken further steps to block all other traffic, in which case your efforts will be futile.
However, assuming that your provider is willing to forward all of your traffic, what you need to do is the following.
First, you need to find out whether there is a gateway willing to accept your connection on the other side, because we need its IP address. I will give you four methods to do this.
1) With the pc connected to the VPN, try the following command:
sudo dhclient -v tun0
If everything goes well, you should see a reply containing this line:
DHCPOFFER of a.b.c.d from x.y.w.z
x.y.w.z is the IP address of the local gateway. You may have to shutdown your VPN after this test, and maybe even to reboot your pc, because we will have just messed up the routing table pretty well.
2) Alternatively, you may try navigating to one of the allowed sites (those that appear in your routing table as going through the tun0 interface), then issuing the command:
ip neigh show
You should get a list of pcs contacted through the ARP protocol, with MAC and IP address; most likely, you will receive either zero or one reply. If you get a single reply, then that's your router.
3) If you get no such reply, then you may try with
sudo nmap -sn 10.0.0.0/8
(which is going to be very slow). Your gateway will be one of the pcs listed, most likely the one with address ending in .1 or in .254, if any such exist.
4) Use the tcpdump command:
sudo tcpdump -n -i tun0
and see the IP addresses spewed out by the command.
If you get no proper reply to this test either, it means someone has really tightened the screws in his network.
But let us be optimistic, and suppose you now have a candidate IP address x.w.y.z for the remote router. You will need to delete the default gateway, (as sudo!):
ip route del default via 192.168.1.254
an add the new one:
ip route add default via x.w.y.z
and try to navigate.
Let me repeat: since your provider has allowed traffic only to a few selected IP addresses through his VPN, it is possible he may have taken extra measures (=firewall) to prevent a smart user to force his generic traffic through his VPN. In this case, there is nothing you can do. But if he did not, the above steps should help you find a solution.
No comments:
Post a Comment