Creating virtual network interfaces in RHEL/CentOS

Setting up an additional IP address for a webserver or any other service/reason is easy on RHEL/CentOS.

Go to /etc/sysconfig/network-scripts and copy existing script:
cp ifcfg-eth0 ifcfg-eth0:0
If you will need to create more IP addresses just increase the number after colon in the file name and in the device name field of course.

Now you need to edit ifcfg-eth0:0 and put there new IP address, it should have at least the following entries included:

DEVICE=eth0:0
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.0.182
NETMASK=255.255.255.0

Finally restart network services:

service network restart

You should be able to see new virtual interface up and running:

# ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000

    link/ether 08:00:27:18:08:b3 brd ff:ff:ff:ff:ff:ff

    inet 192.168.0.181/24 brd 192.168.0.255 scope global eth0

    inet 192.168.0.182/24 brd 192.168.0.255 scope global secondary eth0:0