Hello, On Fri, 11 Jun 2004, Denis Vlasenko wrote: > Hmmm... do I have to set a *routing dest address* field > to set src ip address of my UDP packet? Try such function: static int my_send(int fd, unsigned srcip, (struct sockaddr *) remote, char *data, int len) { struct iovec iov = { data, len }; struct { struct cmsghdr cm; struct in_pktinfo ipi; } cmsg = { .cm = { .cmsg_len = sizeof(struct cmsghdr) + sizeof(struct in_pktinfo), .cmsg_level = SOL_IP, .cmsg_type = IP_PKTINFO, }, .ipi = { .ipi_ifindex = 0, .ipi_spec_dst = srcip, }, }; struct msghdr m = { .msg_name = remote, .msg_namelen = sizeof(struct sockaddr_in), .msg_iov = &iov, .msg_iovlen = 1, .msg_control = &cmsg, .msg_controllen = sizeof(cmsg), .msg_flags = 0, }; return sendmsg(fd, &m, MSG_NOSIGNAL|MSG_DONTWAIT); } Regards -- Julian Anastasov <ja@ssi.bg> - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html