is there any way to track/debug the tunnel traffic.

it was working, we moved the client and now no activity can be seen.

you can install tcpdump on the node. ie. for Ubiquiti...

opkg update

opkg install tcpdump

tcpdump -i eth0.1 port 5525 -A -v

would you try to connect?

Of note, tcpdump is actually installed by default on Ubiquiti so no need to install it just run it (Linksys devices on the other hand don't have enough space for it in the 4mb limit with everything else for us to include it by default so must be installed manually)

You may try running "logread"  - It will show you the log output to see if your getting connections or not.

Also a "ps w|grep vtun" will help as well as you should see if memory is correct you should seel statuses like "[connected]" or "[connecting]" etc.

good point Conrad, with one correction and an additional tip:

Since the tunnel server/client will only run on a Linksys GS box, there is certainly enough space to install tcpdump on them. I have it on my GS2 client and my NS2 server.

one additional tip to test a server's ability to receive the vtun traffic thru an external firewall:

on the remote network, it's useful to see if your vtun traffic is getting to the target nodes vtun server process thru their firewall.

An EASY test is to use telnet. from my osx commandline, i run:

telnet remoteServerDNSnameOrIPAddress 5525

If you get back a response that says "VTun version 2.6", then the remote firewall is properly forwarding to your server.