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Add a Class-C IP Block to Your Server

This guide explains what a Class-C block is and how to add its addresses to a server.

Dedicated Servers2 min read8 steps3 screenshots

Note: This guide needs root access to the server. It is for VPS and dedicated server owners. The steps below suit a server with WHM.

What is an IP address?

An IP address is a number that names a computer on the internet. It works like a house address. A website can use one IP address. A Class-C block is a group of 256 addresses that sit together, such as 203.0.113.0 to 203.0.113.255. Some of those addresses are reserved for network use, so you cannot use all of them.

People use extra addresses for separate SSL certificates, email reputation or to host sites apart from each other.

Before you begin

  • You must get the block first. Ask Hostvento support if you can add one to your server. Details and terms come from them.
  • Ask for the network details. You need the netmask and the gateway. The netmask tells the server how big the block is. The gateway is the door to the wider internet.

Open a support ticket to ask.

Warning: Wrong network settings can cut off your server from the internet. Do not change the main address. Add new ones only.

Steps in WHM

  1. Log in to WHM as root.
  2. Search for Add a New IP Address and open it.
    manage ips
  3. Enter the first address or a range. WHM accepts a range of addresses.
  4. Enter the subnet mask the support team gave you.
  5. Click Submit.
  6. Open Show or Delete Current IP Addresses to see the list.
  7. Check that the new addresses appear.
    manage ipv4 addresses

Steps on the command line

You can also add one address by hand. For example, on a server that uses eth0 as its network name:

ip addr add 203.0.113.10/24 dev eth0

This gives the network card a new address. It disappears after a reboot unless you save it in the network settings files. Check your Linux version to see where those files live.

Test it

  1. From another computer, ping the new address.
ping 203.0.113.10

Replies mean it works.

Tip: Use the addresses for sites in WHM under Change Site's IP Address. Do not forget to update DNS records after.

Quick recap

  • A Class-C block is a group of 256 neighbouring IP addresses.
  • Ask Hostvento support first for the block and network details.
  • Add the addresses in WHM under Add a New IP Address.
    Adding C-Class IP Addresses To Your Server
  • Test with ping and update DNS after.