[tproxy] Tproxy changes for performing dual NAT

Hi Bazsi, Thank you for a nice work that provides real transparency to both web users and web servers. :) I am using cttproxy v2.0.6 on linux kernel v2.6.18.1 along with Squid v2.6. Cttproxy is used to provide transparency to both web server and client and also to cache web requests. Sometimes it is required to SNAT HTTP traffic that is not possible with Cttproxy-v2.0.6; since double NAT is not possible. Here is a patch attached to solve that issue. This patch helps to perform SNAT in POSTROUTING chain of TPROXY table as well as in POSTROUTING chain of NAT table. Can you please validate this patch let me know your concerns. -- Regards, Arun S.