I'm trying to create a bridge using the bridge-utils package under kubuntu 8.04.1.

= /etc/network/interfaces =
auto lo
iface lo inet loopback

# from http://www.virtualbox.org/download/UserManual.pdf
auto br0
iface br0 inet dhcp
bridge_ports eth0

This worked fine the first time I did a "/etc/init.d/network restart" ... However, whenever I reboot my machine the network is down, which is probably due to a defect routing table:

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface * U 0 0 0 br0 * U 0 0 0 eth0
link-local * U 1000 0 0 br0
default tor.xxxxxxx UG 0 0 0 eth0
default tor.xxxxxxx UG 100 0 0 br0

If I remove the routes using eth0 manually, the network is up again. Thread http://ubuntuforums.org/showthread.php?t=807563 seem to describe the same problem, but the solution found there (disabling the bridge) is no alternative to me, I'm afraid.

Does anybody have an idea where the ambiguous routes to eth0 may come from?