Hi, I have two tun interfaces on my box and I was trying to route packets between the two local addresses through a "userspace router" hooked up to the file descriptors of the tun devices. I see the packet appearing on both the interfaces (using tcpdump -i) but my (udp) server listening for my packets on a particular port doesn't get any of them. I force the packets to not take the localhost route by explicitly specifying the interface on which I want the packet to be sent (I think socat udp4:<dest addr>:<port>,interface=<ifname> ...) does it using setsockopts() ). In other words it seems that if linux receives a packet through an interface (not the loopback) which has a src address equal to one of the local addresses then the packet is not sent to the server listening for it. Is there a way to work around this? Searching for this on the web gave me a pointer to a mail in which routing packets through an ethernet crossover (between two NICs connected to the same computer) was discussed. It seems that there is a small patch for it, but I was hoping if somebody had tricks to do it using configuration changes (routing, /proc/sys settings etc) only. Thanks for your attention! Ritesh -- http://www.cs.unc.edu/~ritesh/ - : send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html