Configure static IP address on CentOS

After a fresh installation CentOS uses DHCP (dhclient -v) to assign an IP to the machine, which keep in changing on reboots, or service restarts, etc.

Use-case: Various service setups, especially involving a clustered configuration we need to set a fixed IP for each machine, so they can communication with each other, in case of DHCP the installation may break on the reboot, as anyone of the machine gets a new IP address. So the first step is to set a static IP address.

Step 0 – Get ethernet interface name

You can get it using any of the following commands – the name can be in different formats ethx, ensxx, enpxx, for example, eth0, ens03, enp0s3, etc.

or,

or,

Output:

Step 1 – backup resolv.conf

Can be updated by the NetworkManager service – in case DNS is specified in the interface conf.

Step 2 – Edit Ethernet script file

The usual path to the ethernet conf is /etc/sysconfig/network-scripts/ifcfg-<your-interface-name>
The content of the original file:

Now, update the script for the following parameters

Output:

Step 3 – Update network file and DNS

Set the gateway at /etc/sysconfig/network. You can get the gateway using any of the following commands:

or,

Output:

Update the gateway

Update the DNS

You can use any of the Google’s nameservers i.e. 8.8.8.8, or 8.8.4.4.

Step 4 – Restart your network or reboot

Step 5 – Ping verify