Adding Alias IP to a NIC

http://www.cyberciti.biz/faq/linux-creating-or-adding-new-network-alias-to-a-network-card-nic/

{{{ Using ifconfig command line You can use ifconfig command to configure a network interface and alias. For example:

   * eth0 NIC IP – 192.168.1.5
   * eth0:0 first NIC alias: 192.168.1.6

To setup eth0:0 alias type the following command as the root user:

1. ifconfig eth0:0 192.168.1.6 up

Verify alias is up and running using following command:

1. ifconfig –a
2. ping 192.168.1.6

However if you reboot system you will lost your alias. To make it permanent you need to add it network configuration file:

If you are using Debian Linux Open the file /etc/network/interfaces:

1. vi /etc/network/interfaces

Append text as follows:

auto eth0:1 iface eth0:1 inet static name Ethernet alias LAN card address 192.168.1.7 netmask 255.255.255.0 broadcast 192.168.1.255 network 192.168.1.0

Save the file and restart the network:

1. /etc/init.d/networking restart

If you are using Red Hat / Fedora Linux Copy etc/sysconfig/network-scripts/ifcfg-eth0 file etc/sysconfig/network-scripts/ifcfg-eth0:0 -

1. cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:0

Open file /etc/sysconfig/network-scripts/ifcfg-eth0:0 using vi text editor:

1. vi /etc/sysconfig/network-scripts/ifcfg-eth0:0

Find entry that read as follows:

DEVICE=eth0

Replace with:

DEVICE=eth0:0

Find entry that read as follows:

IPADDR=xxx.xxx.xxx.xxx

Replace it with your actual IP address:

IPADDR=192.168.1.7

At the end your file should like as follows:

DEVICE=eth0:0 IPADDR=192.168.1.7 NETMASK=255.255.255.0 NETWORK=192.168.1.0 ONBOOT=yes NAME=eth0:0

Open file /etc/sysconfig/network-scripts/ifcfg-eth0 and make sure file does not have a GATEWAY= entry:

1. vi /etc/sysconfig/network-scripts/ifcfg-eth0

Find the entry that read as follows:

GATEWAY=192.168.1.254

Remove or comment it out by prefixing # (hash) :

1. GATEWAY=192.168.1.254

Save the file. Add the GATEWAY= to your /etc/sysconfig/network:

1. vi /etc/sysconfig/network

Append or modify GATEWAY entry:

GATEWAY=192.168.1.254

Save the file. Reboot the system or run the following command:

1. ifup eth0:0

OR

1. service network restart

See also: }}}

http://www.cyberciti.biz/tips/freebsd-how-to-setup-2-ip-address-on-one-nic.html

{{{ It is possible to create network alias or assign 2 ip address to single NIC under FreeBSD.

My setup: lnc0 - IP : 192.168.1.1/255.255.255.0 lnc0 alias - IP : 192.168.1.5/255.255.255.255

Note: Netmask must be diffrent otherwise you will get an error ifconfig: ioctl (SIOCAIFADDR): File exists

A) From command line use ifconfig command as follows:

1. ifconfig lnc0 192.168.1.5 netmask 255.255.255.255 alias

B) You can setup this alias in /etc/rc.conf file by appending following text, so that next time FreeBSD comes up (after restart/shutdown) it will create alias for you: ifconfig_lnc0_alias0=”192.168.1.5 netmask 255.255.255.255″

C)Restart FreeBSD network service using following script:

1. /etc/netstart

D) Display alias and real ip using ifconfig lnc0 command:

1. ifconfig lnc0

lnc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 inet6 fe80::20c:29ff:fe01:ddbd%lnc0 prefixlen 64 scopeid 0×1 inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255 inet 192.168.1.5 netmask 0xffff

Read ifconfig man page. }}}