You may need to setup several ip addresses to be served by the same physical network interface. You may need to setup few (secondary)  IP addresses to be served by same virtual network interface. For example If you are using Apache server very useful for setting up multiple virtual sites for a single network interface with different IP addresses.

The below instruciton for all  Linux distributions like CentOS, RHEL, Fedora,...

Create Virtual Interface:

Default interface name is "ifcfg-eth0" this is located in /etc/sysconfig/network-scripts, create interfaces for to accomplish  many ip addresses. This post describes configure 2 IP addresses.

# cd /etc/sysconfig/network-scripts

# ls


ifcfg-eth0        ifdown-bnep  ifdown-isdn    ifdown-sit     ifup-bnep  ifup-isdn   ifup-ppp     ifup-wireless      

ifcfg-lo          ifdown-eth   ifdown-post    ifdown-tunnel  ifup-eth   ifup-plip   ifup-routes  init.ipv6-global

netowrk-functions ifdown-ippp  ifdown-ppp     ifup           ifup-ippp  ifup-plusb  ifup-sit     net.hotplug

ifdown            ifdown-ipv6  ifdown-routes  ifup-aliases   ifup-ipv6  ifup-post   ifup-tunnel  network-functions-ipv6


Assume that the below interfaces assigning IP addresses,

ifcfg-eth0:0 = 192.168.0.210

ifcfg-eth0:1 = 192.168.0.211
 
# vim ifcfg-eth0


TYPE=Ethernet

DEVICE=eth0

IPADDR=192.168.0.110

NETMASK=255.255.255.0

BROADCAST=192.168.0.255

NETWORK=192.168.0.200

ONBOOT=yes

GATEWAY=192.168.0.1


Now, copy the configure file,
 
# cp ifcfg-eth0  ifcfg-eth0:0

# cp ifcfg-eth0  ifcfg-eth0:1

Configure Interface:

Now, open the configure file everyone and update the parameters,
 
# vim ifcfg-eth0:0


TYPE=Ethernet

DEVICE=eth0:0

IPADDR=192.168.0.210

NETMASK=255.255.255.0

BROADCAST=192.168.0.255

NETWORK=192.168.0.200

ONBOOT=yes

GATEWAY=192.168.0.1

 
# vim ifcfg-eth0:0


TYPE=Ethernet

DEVICE=eth0:1

IPADDR=192.168.0.211

NETMASK=255.255.255.0

BROADCAST=192.168.0.255

NETWORK=192.168.0.200

ONBOOT=yes

GATEWAY=192.168.0.1


Once you have verified all the changes restart your network service,
 
# /etc/init.d/network restart

# ifconfig


eth0      Link encap:Ethernet  HWaddr 50:b7:c3:5a:1e:6e  

          inet addr:192.168.0.110  Bcast:192.168.0.255  Mask:255.255.255.0

          inet6 addr: fe80::52b7:c3ff:fe5a:1e6e/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:56702 errors:0 dropped:0 overruns:0 frame:0

          TX packets:34554 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:34300113 (34.3 MB)  TX bytes:5643764 (5.6 MB)





eth0:0    Link encap:Ethernet  HWaddr 01:26:EE:C3:52:C3  

          inet addr:192.168.0.210  Bcast:1192.168.0.255  Mask:255.255.255.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          Interrupt:11 



eth0:1    Link encap:Ethernet  HWaddr 14:CC:EE:A1:12:A2

          inet addr:192.168.0.211  Bcast:1192.168.0.255  Mask:255.255.255.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          Interrupt:11 



lo        Link encap:Local Loopback  

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:1081128 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1081128 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:1656298983 (1.5 GiB)  TX bytes:1656298983 (1.5 GiB)


Also ping the both IP address, 192.168.0.210,  192.168.0.211.