How to bind range of IP address to Ethernet
In this short post we will see how we can quickly add a range of IPs on any RedHat based system (RHEL, Centos, Fedora, etc). When you have to add many IPs to a system this can be quite handy and can save a lot of time.
Normally when you add a new IP to a network interface in a RedHat based system you create a file ifcfg-eth0:x in /etc/sysconfig/network-scripts/. For example:
*************************************
/etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE=eth0:0
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.0.100
NETMASK=255.255.255.0
NETWORK=192.168.0.0
BROADCAST=192.168.0.255
TYPE=Ethernet
*************************************
Similar to the above example you can create several aliases. But what if you have to add a lot of IPs that are in a range like this? Let’s say that we want to add 100 IPs this way… this is possible, but not very effective, right? RedHat based systems offer a method to bind a range of IPs in a quick way allowing us to eliminate the need to create a lot of files and saving us time doing this.
Create a file /etc/sysconfig/network-scripts/ifcfg-eth0-range0 if this doesn’t exist, or just add to it if you already have it, the following lines:
/etc/sysconfig/network-scripts/ifcfg-eth0-range0
IPADDR_START=192.168.0.100
IPADDR_END=192.168.0.200
CLONENUM_START=0
where:
IPADDR_START —— the first IP in the reange.
IPADDR_END —— the last IP in the range.
CLONENUM_START —— the number that will be assigned to the first IP alias interface (eth0:0 in this example).
That is, CLONENUM=1 will add the IP range to the interface eth1.
If you need to add more ranges of IPs then just use a different file, for ex. ifcfg-eth0-range1, for each one of the ranges. You need to be careful and use the proper CLONENUM_START to not overwrite other aliases. Once you have configured the range/s of IPs you just need to restart the network service in order to activate it:
/etc/init.d/network resatart
You can then verify if all the IP aliases have been currectly added by issuing : ip a or ifconfig
Category: Tips for linux
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