Configure Network Interface Using Command-Line
You can configure a network interface from the command line. You configure your network client hosts with the command line by using commands to change your current settings or by editing a number of system files.
Find Network Interface Card
When setting up your network you will need to know the network interface cards on your computer. The interface name of cards for different vendors may be different, which is why this step is needed.
ls /sys/class/net
This will list the interface names for all NICs on your computer. It will probably include eth0 (hardwired NIC), lo (loopback interface for the localhost), and something for your wireless card (like wifi0, or wlan0).
Configuring Static IP Address For Your Network Card
Configure a Static IP address by editing /etc/network/interfaces. Replace eth0 with your network interface card (see Find Network Interface Card).
sudo nano /etc/network/interfaces
# The primary network interface auto eth0 iface eth0 inet static address 192.168.2.33 gateway 192.168.2.1 netmask 255.255.255.0 network 192.168.2.0 broadcast 192.168.2.255
For these settings to take effect you need to restart your networking services.
sudo /etc/init.d/networking restart
Setting up Second IP Address or Virtual IP Address
If you need to set up a second ip address you need to edit the /etc/network/interfaces.
sudo nano /etc/network/interfaces
auto eth0:1 iface eth0:1 inet static address 192.168.2.33 netmask 255.255.255.0 network x.x.x.x broadcast x.x.x.x gateway x.x.x.x
You need to enter all the details like address,netmask,network,broadcast and gateways values.
For these new settings to take effect you need to restart networking services using the following command
sudo /etc/init.d/networking restart
Setting Your Hostname
The hostname command allows you to directly query, or set, the hostname from the command line.
You can see your current hostname with
sudo /bin/hostname
To set the hostname directly you can become root and run
sudo /bin/hostname newname
When your system boots it will automatically read the hostname from the file /etc/hostname
Setting up DNS
You can add hostname and IP addresses to the file /etc/hosts for static lookups.
To cause your machine to consult with a particular server for name lookups you simply add their addresses to /etc/resolv.conf.
For example a machine which should perform lookups from the DNS server at IP address 192.168.3.2 would have a resolv.conf file looking like this
sudo nano /etc/resolv.conf
enter the following details
search myaddress.com nameserver 192.168.3.2
Configuring DHCP Address for Your Network Card
The DHCP address can be configured by editing the following file /etc/network/interfaces. Replace eth0 with your interface card (see Find Network Interface Card).
sudo nano /etc/network/interfaces
# The primary network interface – use DHCP to find our address auto eth0 iface eth0 inet dhcp
Howto Set MTU for a DHCP Connection
Although this is not documented in the manual for interfaces, MTU for a DHCP connected device can be set in the /etc/network/interfaces file. To do so you need to append the 'pre-up' command to the 'iface' section of the relevent interface.
iface eth0 inet dhcp
pre-up /sbin/ip link set $IFACE mtu 1492The above example sets the MTU for device eth0 to 1492, the usual MTU for a PPPoE ISP connection. This however is only needed if connections seem to hang otherwise (with the default of 1500).
This tip was found on http://glasnost.beeznest.org/articles/290.