Support for clients on realservers

Maybe I'm missing something, but out-of-the-box `seesaw` doesn't seem to support having the backend servers initiate TCP connections to outside servers (say, Gmail mail servers) for LVS-DR.

Here is a longer form explanation of an example setup with one outside client, one outside server, seesaw load balancer with a `VIP`and three backend real servers:

`CIP` = Client IP address (outside)
`SIP` = Server IP address (outside)
`VIP` = Virtual IP address of the seesaw service / `vserver`
`RIP1` = Real (backend) server IP address number 1
`RIP2` = Real (backend) server IP address number 2
`RIP3` = Real (backend) server IP address number 3

Typically for LVS-DR, a client from outside will initiate TCP (say, port 25) connection with [source IP=`CIP`, source port=34567, destination IP=`VIP`, destination port=25] to the load balancer. Load balancer (if it has a matching `vserver` configured for port 25) then forwards via MAC address re-write to one of the backend servers, say server with `RIP3`. TCP Server living on that server sees a TCP `SYN` packet with [source IP=`CIP`, source port=34567, destination IP=`VIP`, destination port=25], the `VIP` being configured on one of its dummy interfaces. The TCP server on port 25 on the backend server with `RIP3` will then respond with a `SYN,ACK` TCP packet with [source IP=`VIP`, source port=25, destination IP=`CIP`, destination port=34567] directly to the router and the packets end up on the client with IP address=`CIP` that originally initiated the TCP connection.

I am just describing this for clarity. This is what normal LVS-DR looks like and what `seesaw` typically does. This is when TCP connections are initiated from an outside client towards `seesaw`/`VIP`.

What about the reverse? Say I have a TCP client on one of the real (`backend`) servers. I want this client to initiate TCP connection with [source IP=`VIP`, source port=34568, destination IP=`SIP`, destination IP=25]. For the initial `SYN` package, this works fine, as it is send directly via the router, not through the `seesaw` director node. The outside server listening on `SIP` then responds with `SYN,ACK` packet with [source IP=`SIP`, source port=25, destination IP=`VIP`, destination port=34568]. Then the problem occurs: The `seesaw` node sees the packet coming in and, since its sent towards a port that isn't configured as a `vserver` (ephemeral port 34568), drops the packet and the connection isn't established.

Now, if I add the following configuration to the seesaw node by hand, it does work:
```
# iptables -I INPUT -p tcp -m tcp -d $VIP --sport 25 -j MARK --set-mark 0x1
# ipvsadm -A -f 1 -s rr
# ipvsadm -a -f 1 -r $RIP3 -g # Just using RIP3 as an example here
```

Is there any other way to do this? As it looks now, I would have to fork seesaw to add this functionality into the code so it works with `seesaw` node switchover etc.