Hello, maybe my first email doesn't exactly describe my problem. I'd like to test in the source code for some #ifdef's regarding to IPv4/IPv6/UNIXDomain. In the book 'UNIX Network Programming. Vol.1' from R.W.Stevens I can see something like #ifdef IPV4 #ifdef IPV6 #ifdef UNIXdomain #ifdef HAVE_SOCK_SA_LEN (couldn't remember exactly) ... The constants should indicate the support from linux. If I test this macros in my code on linux - it seems they are not defined. Where can I find this things? with regards, Oliver - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org