How to keep network interface up, during cable disconnects

Question

I have two ubuntu PCs whose network cards connected directly to each other with cross-over cable. I have assigned ip addresses manually to their interfaces using command similar to

 ifconfig eth0 192.168.2.1 up

The problem is that every time I physically disconnect those PCs, the connection goes down and next time when I connect it back, the ip addresses are lost. Also whatever applications I have bound to those adresses before disconnect needs restarting two. Is there a way to keep networ interfaces UP during physical cable disconnect so the apps which create listening sockets on those addresses, would not need to be restarted after re-connect?

Answer 1

Edit your /etc/networking/interfaces and add:

iface eth0 inet static
    address 192.168.2.1
    netmask 255.255.255.0

Then eth0 has static ip always.

More info on configuring interfaces with man interfaces

You can also use Network Connections graphical setup tool from your system preferences. You can configure network-manager to use static ip-addresses from there.