how to forward ip tunnel's output
I'm trying to implement a routing short-cut solution, whose requirement is as following:
server1(Linux) sends ip packets(destined to server3) to server2(Linux) via an ip tunnel between them, server2 forwards the ip tunnel's output (the inner ip packets) to server3. Each server has only one NIC and a public ip associated with it. All servers can communicate with each other.
I'm sure the ip tunnel between server1 and server2 was configured correctly and worked well. server2's ip_forward was enabled too. On server2, I can capture the traffic on the ip tunnel interface, and they are originated from server1 and destined to server3. The problem is server2 does not forward the ip tunnel's output at all.
On server2, I just run "echo 1 > /proc/sys/net/ipv4/ip_forward". Is there anything I missed for enabling ip_forward?
Or originally, ip forward can't work on servers with only one NIC, can it?
Any help would be greatly appreciated!
Thanks a lot!