Dear sir, SORRY FOR MINE POOR ENGLISH. this is mine configuration. a----------------->b------------------------------------------->c 10.10.10.5(global ip) 10.10.10.5 port=7500 port=5500 server s1 server s1 >now server s1 is running on both the machine but on different port. Objective --------------------- >if 'a' sends a packet(ip=10.10.10.5 dport=7500) .then this packet is recive by 'b' >Otherwise forward it to 'c' --------------------------- >i have made modification on the source code(also ip_forward enabled). >for udp its no problem >for tcp,one way forwarding is no problem.('a' sends a syn packet having destination ip=10.10.10.5 and dport=5500 to 'b'. now 'b' forwards it to 'c') >now the ack packet 'c' sends to 'b'.but 'b' can't deliver it to 'a'. >i have followed the same techineque for forwarding from 'b' to 'a'(as that of i do while forwarding 'b' to 'c') skiping the source validation .still it hangs sometimes not always.i gives the cases CASE 1: ------- >send a udp packet having(ip=10.10.10.5 port=5500) from 'a'.it reaches at 'c' >now send a packet udp packet from 'c' to 'a'.it reaches >now send a tcp packet from 'a'(ip=10.10.10.5 dport=5500).it reaches to 'c' also reply comes to 'a'.its working, its fine. CASE 2: ------- >if i first tries to send a tcp packet having(ip=10.10.10.5 port=5500) then system 'b' hangs. CASE 3: --------- >if i first send a udp packet from 'c' to 'a'.system 'b' hangs. i did not getting the problem. With Regards kanhu <A target="_blank" HREF="http://clients.rediff.com/signature/track_sig.asp"><IMG SRC="http://ads.rediff.com/RealMedia/ads/adstream_nx.cgi/www.rediffmail.com/inbox.htm@Bottom" BORDER=0 VSPACE=0 HSPACE=0></a>