While upgrading a remote server from sarge to etch including the new kernel, the server did not come up. After attaching a console (thanks Hetzner!) I found out that the network interface got mysteriously renamed to eth2!
After snooping around a bit, I found out that the culprit was udev, more specifically /etc/udev/rules.d/z25_persistent-net.rules which says:
# This file was automatically generated by the /lib/udev/write_net_rules
# program, probably run by the persistent-net-generator.rules rules file.
#
# You can modify it, as long as you keep each rule on a single line.
# MAC addresses must be written in lowercase.
# PCI device 0x1106:0x3065 (via-rhine)
SUBSYSTEM=="net", DRIVERS=="?*", ATTRS{address}=="00:0c:76:af:2f:9d", NAME="eth0"
It also contained two entries for bogus eth0 and eth1 (usb dongle got identified as a network card?). After removing the and relabeling interfaces everything is back to normal now.
