What communication can be intercepted by network I'm connected over VPN to?

Question

I have to connect to client's network over VPN, and I was wondering if the client can intercept (and read) my Google Talk messages (or any other IM communication) while I'm VPN-ing.

My main concern is them having access to our internal conversations.

Suggest workarounds if you have any.

Answer 1

That depends on how you route your internet connection. In most cases, you'll just route addresses from the client's network (typically in a subnet of 10.0.0.0/8).

Type route in a console to see your routing table. The first default entry determines how your regular internet connection flows. For example, the following configuration does route over the VPN:

0.0.0.0         172.16.0.5      0.0.0.0         tun0 # default via tun0(=VPN)
172.16.0.5      0.0.0.0         255.255.255.255 tun0
1.2.3.4         192.168.1.1     255.255.255.255 wlan0
192.168.1.0     0.0.0.0         255.255.255.0   wlan0
0.0.0.0         192.168.1.1     0.0.0.0         wlan0 # default via wlan0(local)

A simple alternative is checking whether your IP address changes when you connect to the VPN.