Linux Ubuntu losing static IP address on disconnect

If you are losing the interface static IP address on disconnect in your Linux Ubuntu 9.x , this happens because Ubuntu has its own network manager and probably you're trying to configure the static IP in the usual way, editing the config file /etc/network/interfaces.

There are two solutions:


1) Use the Network-Manager

1.1) Remove all manually configurations from /etc/network/interfaces

The file  /etc/network/interfaces  should be like this:

auto lo
iface lo inet loopback

 1.2) Configure your network interface static IP address through the Network-Manager in Gnome panel.

1.3) Restart Network-Manager service:

# service network-manager restart
 

2) Stop Network-Manager Service

2.1) Stop Network-Manager service with:


# service network-manager stop

2.2) To permanently disable Network-Manager
edit /etc/init/network-manager.conf and comment the line

## exec NetworkManager

2.3) Configure your network in the usual way (manually), editing /etc/network/interfaces

# vi /etc/network/interfaces 

auto lo

iface lo inet loopback

auto eth0

iface eth0 inet static
address 192.168.1.5
netmask 255.255.255.0
gateway 192.168.1.1

Restart the network service:


# ./etc/init.d/networking restart

For more information about this issue: 

1. http://en.kioskea.net/faq/979-having-a-static-ip-address-under-ubuntu-8-10
2. http://www.cyberciti.biz/faq/setting-up-an-network-interfaces-file/

I hope this information helps.