I have a server with the current /etc/network/interfaces:
auto lo iface lo inet loopback auto em1 iface em1 inet dhcp auto em1:1 iface em1:1 inet static address 192.168.168.1 netmask 255.255.255.0
dhclient.conf file is default, nothing edited. If I connect 2 machines together, ethernet port on pc1 to ethernet port on pc2, the connection works great for 5 minutes (this just happens to be the default dhclient.conf timeout). If I change the dhclient.conf timeout to 20 seconds, the machines stay connected for 20 seconds then kill both interfaces (em1 and em1:1). I can do ifdown to both connections & ifup to bring them up, but they will just die again in whatever the dhcp timeout is.
/etc/network/interfaces has to be like that, DHCP on em1 with an alias or virtual connect for em1:1 that is static. I could set the dhcp timeout to like 9999999999999999999999999999999999999, but eventually it will hit that timeout & bomb. No errors in the log files.
Any ideas? No Network Mangler suggestions please :)