how to access computers on dd-wrt LAN using hostnames, when connected to a university VPN?

Question

So I have a dd-wrt router connected to my cable modem. Behind that router on my lan are computers with hostnames le1700, wind and t60p. On each machine, I am simply able to do a nslookup and it returns the correct address. All is good.

Then, I connect to my university VPN (cisco client) with, say, le1700. Now bam, I can no longer access t60p and wind with their hostnames. I can still use their IP addresses, but I can't use their hostnames.

Now, this is understandable. When I am not on a VPN, nslookup (Windows) tells me the server it is using for name resolution is my router itself (which is thanks to dnsmasq, I am guessing). However, when on the VPN, the server used is that of my university.

So my question is, when connected to university VPN, how do I still access my LAN computers through hostname? I am kind of hoping that there's a way I can say "MyHomeNetwork" will always refer to LAN, and therefore even if connected to VPN "t60p.MyHomeNetwork" still refers correctly.

Any suggestions?

Answer 1

Easiest way to do that is to put your DNS records manually to hosts file. hosts is local database for static (manually set) DNS records.

In Mac OS X / Linux see /etc/hosts, in Windows C:\Windows\system32\drivers\etc\hosts.

As you already guessed, just setting up DNS records is not enough to have connectivity to your computers, as all traffic is going through VPN tunnel to university network, and your router is blocking incoming connections.

You can fix this by adding static route for your local computers. In Linux:

route add -host 192.168.0.2 dev eth0

will add static route to 192.168.0.2 via eth0, instead of VPN tun/tap device.

Answer 2

The Cico VPN system uses something called Split DNS to facilitate this. Unfortunately this is configured at the VPN Server end and not at the client.

Split DNS should send a list of university domains to the client and these domains are then the only ones resolved using your campus DNS servers.

You should speak to the computer support people at your university about whether Split DNS is set up on thier VPN system or not and find out why it hasn't been.