Using one VPN through another?

Mattus · 16 Nov 2008 at 17:32

Hi guys,

I'm a Uni student who's spending a year abroad in Germany. I have a VPN connection to my home Uni through the Cisco VPN client, which I have to use to access resources on the Uni network.

The problem is that in my halls here in Germany, I have to connect through a VPN (this time set up directly through Windows Vista) to get an internet connection in the first place. When I'm connected through the German VPN, my Oxford VPN doesn't work. It establishes a connection, but for as long as I stay connected to Oxford I have no internet connectivity at all.

So is it possible to make one VPN work through another? Is there a setting I can change to get this to work?

Tui · 16 Nov 2008 at 18:42

Cisco say no in their FAQ, stating there are known issues.

sparkey196 · 16 Nov 2008 at 23:13

If the oxford vpn gatway supports NAT-T (UDP encapsulation) or SSL-VPN it should work as this is a regular udp connection, like streaming video or file sharing. You will not be able to traverse the German VPN if oxford only supports normal IPSEC.

It might be a limitation of the cisco client software so you may want to take a look at the shrew client. Good luck.

Mattus · 16 Nov 2008 at 23:17

Thanks guys, that's very helpful. What do you make of this? Looks to me like it can only be an IPSEC connection, at least if I use the Cisco client.

Tui · 17 Nov 2008 at 20:04

Yes, the Cisco VPN client is only IPSEC.
Back to your original post:

When I'm connected through the German VPN, my Oxford VPN doesn't work. It establishes a connection, but for as long as I stay connected to Oxford I have no internet connectivity at all.

This doesn't mean the Cisco VPN client doesn't work, unless you can't connect to the Oxford networks.
To connect anywhere else, like the internet at the same time, the connection has to allow split tunnelling. This is set up by whatever policy is applied by the server and not the client - even if Allow Local LAN Access is ticked.

sparkey196 · 17 Nov 2008 at 21:24

could the problem be that you are trying to use the oxford vpn as your default gateway (for internet routes) but it only pushes you LAN traffic? If the university suppies and http proxy, you could use that for internet while on the vpn.

Mattus · 17 Nov 2008 at 21:28

Thanks guys, knew this forum wouldn't let me down.

The Oxford VPN normally has full internet connectivity. (Traceroute when connected to the Oxford VPN shows packets being routed through the Oxford network.) If I've followed what you've been saying, the problem must simply be what sparkey mentioned first, namely that IPSEC doesn't allow VPN traversal? I'll have to find out if the server allows connections through another method, though I doubt it does.