Centos: multiple IP addresses

Question

I just bought 10 extra IPs from my host. How do I point these at my CentOS 5 server?

Answer 1

Use IP aliasing on the host.

ifconfig eth0:1 192.168.0.100 netmask 255.255.255.0
ifconfig eth0:2 192.168.0.101 netmask 255.255.255.0

To do it permanently you will have to use the files in /etc/sysconfig/network-scripts/ifcfg-<interface>

And so on. But why do you need multiple IPs for a single host? SSL/TLS?

Answer 2

On CentOS you can use a ifcfg-eth?-range? file to assign multiple IP adresses. For example; you want to assign additional IP adresses to your eth0 interface and you don't have any additional addresses assigned yet. Create the file /etc/sysconfig/network-scripts/ifcfg-eth0-range0:

IPADDR_START=10.0.0.10
IPADDR_END=10.0.0.19
CLONENUM_START=0

When you already have assigned additional IP addresses the CLONENUM_START value should match the next available eth0:x number.

If the IP addresses aren't in order you have to create an ifcfg-eth0:x file for each of the addresses. The content should look like this:

DEVICE=eth0:0
IPADDR=10.0.0.10
NETMASK=255.255.255.0
ONBOOT=yes

Change the DEVICE value to the corresponding filename and run ifup eth0:0 to bring the interface online.