Received UDP packet from unknown source 1.2.3.4 (port 12345)

[Pavel Georgiev]

Hi list, 

I have a VPN mesh with ~10 nodes. A recently added node experience 
the 'Received UDP packet from unknown source' problem. I read in the faq this 
is probably caused by a NAT rule on wither side, but I dont have such rules.

The thing is that IP in the 'Received UDP packet from unknown source ' message 
is exactly what I have configured. The problem solves itself with time and 
this is marked in the logs as:

tinc.vpn[25833]: Lost 219 packets from UA_VPN

When the tunnel works, both source and destination port of the udp packets is 
655, while when I experience the problem the source port of the node that has 
the problems is 602/601. I run tcpdump on that node and the packets have 
exactly that port when they leave the box, so its not something that gets 
rewritten on the way to the other node.

Has anyone else experienced this?

Both nodes running Ubuntu 6.06 / tinc 1.0.4 (binary install).