Recently my vpn stopped working for no apparent reason. I could connect to the vpn using vpnc, but from there I couldn’t ping any of the machines on the network. I had not changed any settings so it was quite puzzling. Friends’ using Windows clients were able to connect with the same vpn parameters without any problems. It looked like a dns lookup problem.
cat /etc/resolv.conf confirmed that the vpn dns was not being used.
After googling around a bit I came across this site which gave me a clue on how to configure my dns look ups. I just had to add the following line to my vpnc config file:
NAT Traversal Mode cisco-udp
Now when I ran vpnc, and ran
cat /etc/resolv.conf, it confirmed that my vpn dns was used! :)
The complete vpnc config file looks like this:
IPSec gateway xxx.xx.xxx.xxx IPSec ID your_id IPSec secret your_secret IKE Authmode psk NAT Traversal Mode cisco-udp