On Fri, 2007-11-02 at 10:14 +0530, Srikanth Pokkuluri wrote: > s = socket(AF_INET6,SOCK_STREAM,PF_INET6); When using TCP (SOCK_STREAM) you don't need to specify a protocol (i.e PF_*), you can just use zero. Give that a try. > SERVER PROGRAM [snip] > s = socket(AF_INET6,SOCK_STREAM,IPPROTO_TCP6); Same here, replace IPPROTO_TCP6 with a zero. hth, -Jim P.