[tproxy] tproxy routing issue within processes in the same machine

[Ming-Ching Tiew]

tproxy has  problem working within 2 processes on the same machine,
ie a client process using tproxy to spoof an IP,  has problem 
communicating  with the server process within the same machine.

It seems tproxy attaches itself to mangle table PREROUTING
chain, that is unable to hook to the in-machine process. I figured
that for it to work, in this case, it needs to be able to attach itself
to the INPUT chain. However that hook is not supported.

Is there a way to get around this problem ?