Hi, When I'm using uml-utilities, specifically the command: sudo tunctl -t tap0 -u test sudo ifconfig tap0 11.1.1.2/16 Or, I've already had virtual network interfaces, I want to delete them: sudo tunctl -d tap0 Sometimes after entering these commands, BIRD(version 1.0.14, alreay been running OSPF protocol) works well and creates new LSAs to flood; but sometimes it crashes.But when I plug in or pull out a twisted pair of a real network interface, it seems that BIRD don't crash. So maybe it's a problem of the "virtual" interface as I thought when testing. But when actually using BIRD for routing in the lab maybe there's no chances to use virtual interfaces. So just reporting this bug. In the debugging file, here may be the related line: May 15 14:24:24 test-ubuntu kernel: [ 292.820382] bird[3797]: segfault at e0000021 ip 08065f83 sp bfee6590 error 5 in bird[8048000+45000] Thanks!