Monday, June 4, 2012

Getting my VM to talk to the office

Admittedly, without putting too much thought into this I expected to be able to configure a VM located on my home machine to connect to a work computer through an already established VPN tunnel without too much hassle.

Well, I ran into a couple bumps getting this system up and running. To be specific I needed sessions to be initiated from both directions (from work to the local VM, and from the local VM to work).

So, basically, the configuration looked like this: There's a VPN tunnel established between work and my home computer. On the home computer there's a VM that needs to reach a system at work, and the system at work needs to reach the VM at home.

Or similar to the illustration below:

So, I guess why I found this interesting is that it wasn't as simple as I initially thought. First stab was to set up the VM and bridging the network on the VM to the host systems interface. But the bridged VM ended up getting the dhcp advertised default route from my home router and therefore packets would not travel through the VPN tunnel. The routing table on the VM looks like (where is the IP of my home router):

root@debian:~# ip route dev eth0  proto kernel  scope link  src 
default via dev eth0