How to assign multiple IP addresses to network adapter on Linux Cloud Servers

Users may need to set up multiple IP addresses to the same network interface for hosting various SSL sites and avoid firewalls or being blacklisted in SPAM filters, etc. This is very useful for setting up multiple virtual sites in Apache using a single network interface with different IP addresses on a single subnet network.

This guide will help you to configure multiple IP addresses on Linux cloud servers.

AlmaLinux/Rocky Linux/CentOS

1. Check the current IP address of the server using the below command.

   # ip addr
   

   

   In the above example, the IP address is 146.196.54.248, you can find your server IP address on eth0 adapter.

2. Run the below command to view the network configuration file contents.

   # cat /etc/sysconfig/network-scripts/ifcfg-eth0
   

   

3. Create the sub-interface configuration files under /etc/sysconfig/network-scripts/ and add the configurations as below, then save and exit the file.

   **ifcfg-eth0:0**
   
   BOOTPROTO=static
   DEFROUTE=yes
   DEVICE=eth0:0
   DNS1=8.8.8.8
   IPADDR=192.168.2.2
   NETMASK=255.255.255.0
   ONBOOT=yes
   STARTMODE=auto
   TYPE=Ethernet
   USERCTL=no
   

   

   NOTE: In this example, 192.168.2.2 is the secondary IP address and you can replace it with the original additional IP address.

   
   

   **ifcfg-eth0:1**
   
   BOOTPROTO=static
   DEFROUTE=yes
   DEVICE=eth0:1
   DNS1=8.8.8.8
   IPADDR=192.168.2.3
   NETMASK=255.255.255.0
   ONBOOT=yes
   STARTMODE=auto
   TYPE=Ethernet
   USERCTL=no
   

   

   NOTE: In this example, 192.168.2.3 is the secondary IP address and you can replace it with the original additional IP address.

4. Reboot the server to reflect the changes. Once rebooted, then log in to the server using SSH and run the below command to display the IP addresses.

   # ip addr
   

   

5. The additional IP addresses will be configured in the eth0:0 and eth0:1 sub interface as in the above screenshot. In this way, you can add a bunch of IP addresses to a Single Network Interface.

Ubuntu 20.04LTS

1. Check the current IP address of the server using the below command.

   # ip addr  
   

   
   

   In the above example, the IP address is 146.196.54.248, you can find your server IP address on ens3 adapter.

2. Run the below command to view the network configuration file contents.

   # cat /etc/netplan/50-cloud-init.yaml
   

   

3. Add the additional IP address to the addresses field in the configuration file once you open the file in a suitable editor such as vi or nano.

   # vi /etc/netplan/50-cloud-init.yaml
   

   

   NOTE: In this example, 192.168.1.3 is the secondary IP address and you can replace it with the original additional IP address.

4. Save the changes execute the command netplan apply.

   # netplan apply
   

   

5. Restart the networking process to reflect the changes using the command.

   # systemctl restart networking.service
   

   

   
   

   Then try to check the interface IP address whether it is reflecting

   # ip addr
   

   

6. Repeat the above steps in case if it requires adding more IP addresses to the NIC interface.

Debian / Ubuntu18

1. Check the current IP address of the server using the below command.

   # ip addr  
   

   
   

   In the above example, the IP address is 146.196.54.248, you can find your server IP address on ens3 adapter.

2. Run the below command to view the network configuration file contents.

   # cat /etc/network/interfaces
   

   

3. Open the configuration file here which is located in /etc/network/interfaces.

   # nano /etc/network/interfaces
   

   
   

   Here, for the additional IP address, you would require to enter the configuration in the following format, where interface-name is the adapter name shown in ip addr output (E.g. ens3) and the additional IP address is the IP address you wish to add.

   iface <interface-name> inet static  
   address <additional-ip address="">
   

   
   

   In the Cloud Servers, the entry will be:

   

   NOTE: In this example, 192.168.0.3 is the secondary IP address and you can replace it with the original additional IP address.

4. Save the changes and restart the network process.

   # systemctl restart networking.service
   

   
   

   To verify the changes, check the interface IP address whether it is reflecting

   # ip addr
   

   

5. Repeat the above steps in case if it requires adding more IP addresses to the NIC interface.

Related tutorials

• How to assign multiple IP addresses to network adapter on Windows Cloud Servers

• How to configure the Static IP Address & Network Card for Linux & Windows Cloud Servers

• How to restart Network Interface / Network Adapter on Linux & Windows Cloud Servers

• How to check TCP/IP configuration with ifconfig on Linux Cloud Servers