LVS-TUN setup - responses from realserver not being let through

[Per Jessen]

I'm setting up an LVS using tunnelling, and I'm having trouble
seeing/getting the responses from the real-server(s). 

For the time being, I'm using one director and just one real-server.
These are leased servers in a remote datacenter.

The setup is as follows:

director RIP = 88.198.41.117  (plus subnet 88.198.198.120/29) 
LVS VIP = 88.198.198.122

real server RIP = 88.198.7.133

My test-client is at 217.8.220.94

On the client, I'm using telnet <VIP> 25 and I've got postfix running on
the real server listening on the VIP.  

Using tcpdump:

1. I see the request arriving on the real server over the tunnel link. 
2. On the real server I see the response being sent. 
3. I see no responses back on my client.

The connection between the real server and the client is fine. 

What am I missing here?  Are the responses from my real server somehow
being blocked because they have a source address of <VIP>?  Or is this
a plain routing problem?



/Per Jessen, Zürich