Objective:

You may need to configure Additional IP addresses on your vps/instances, for example if you are hosting multiple websites or international services. Biswashost Additional IPs allow you to associate multiple IP addresses with a single network interface.

This guide explains how to add Additional IP addresses to your network configuration.

Requirements:

A Public Cloud instance or VPS in your Biswashost account
An Additional IP address or an Additional IP block
Administrative access (root) via SSH or GUI to your instance
Basic networking and administration knowledge

Instructions

The following sections contain the configurations for the most commonly used distributions/operating systems. 
The first step is always to log in to your instance via SSH or a GUI login session (VNC for a Windows instance). 
The examples below presume you are logged in as a user with elevated permissions (Administrator/sudo).

Debian 11:

Step 1: Disable automatic network configuration
Open the following file path with a text editor:

sudo nano /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
Enter the following line, then save and exit the editor.

network: {config: disabled}
Creating this configuration file will prevent changes to your network configuration from being made automatically.

Step 2: Edit the network configuration file
You can verify your network interface name with this command:

ip a
Open the network configuration file for editing with the following command:

sudo nano /etc/network/interfaces.d/50-cloud-init
Then add the following lines:

auto NETWORK_INTERFACE:ID
iface NETWORK_INTERFACE:ID inet static
address ADDITIONAL_IP
netmask 255.255.255.255

Step 3: Restart the interface
Apply the changes with the following command:

sudo systemctl restart networking

Ubuntu 22.04 & Debian 12:

The configuration file for your Additional IP addresses is located in /etc/netplan/. In this example it is called "50-cloud-init.yaml". Before making changes, verify the actual file name in this folder. Each Additional IP address will need its own line within the file.

Step 1: Disable automatic network configuration
Open the following file path with a text editor:

sudo nano /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
Enter the following line, then save and exit the editor.

network: {config: disabled}
Creating this configuration file will prevent changes to your network configuration from being made automatically.

Step 2: Edit the configuration file
You can verify your network interface name with this command:

ip a
Open the network configuration file for editing with the following command:

sudo nano /etc/netplan/50-cloud-init.yaml
Do not change the existing lines in the file; add your Additional IP address according to the example below:

network:
version: 2
ethernets:
NETWORK_INTERFACE:
dhcp4: true
match:
macaddress: fa:xx:xx:xx:xx:63
set-name: NETWORK_INTERFACE
addresses:
- ADDITIONAL_IP/32

It is important to respect the alignment of each element in this file as represented in the example above. Do not use the tab key to create your spacing.

Save and close the file.

Step 3: Apply the new network configuration
You can test your configuration using this command:

sudo netplan try

If it is correct, apply it using the following command:

sudo netplan apply

Repeat this procedure for each Additional IP address.

cPanel (CentOS 7) / Red Hat derivatives:

Step 1: Edit the network configuration file
You can verify your network interface name with this command:

ip a
Open the network configuration file for editing:

sudo nano /etc/sysconfig/network-scripts/ifcfg-NETWORK_INTERFACE:ID
Then add these lines:

DEVICE=NETWORK_INTERFACE:ID
BOOTPROTO=static
IPADDR=ADDITIONAL_IP
NETMASK=255.255.255.255
BROADCAST=ADDITIONAL_IP
ONBOOT=yes

Step 2: Restart the interface
Apply the changes with the following command:

sudo systemctl restart networking

Plesk:

Step 1: Access the Plesk IP management section
In the Plesk control panel, choose Tools & Settings from the left-hand sidebar.

acces to the ip addresses management

Click on IP Addresses under Tools & Resources.

Step 2: Add the additional IP information
In this section, click on the button Add IP Address.

add ip information

Enter your Additional IP in the form xxx.xxx.xxx.xxx/32 into the field "IP address and subnet mask", then click on OK.

add ip information

Step 3: Check the current IP configuration
Back in the section "IP Addresses", verify that the Additional IP address was added correctly.

current IP configuration

Troubleshooting:
First, soft-reboot your instance via the instance's OS or from the Biswashost Control Panel. I
f you are still unable to establish a connection from the public network to your Additional IP and suspect a network problem,
you need to reboot the instance in rescue mode. Then you can set up the Additional IP address directly on the instance.

Once you are connected in rescue mode via SSH, enter the following command:

ifconfig ens3:0 ADDITIONAL_IP netmask 255.255.255.255 broadcast ADDITIONAL_IP up

To test the connection, simply ping your Additional IP from the outside. If it responds in rescue mode, that probably means that there is a configuration error. If, however, the IP is still not working,
please inform our support teams by creating a support request in your Biswashost Control Panel for further investigations.

Windows Server (2016):

Log in to the Biswashost Control Panel, go to the Public Cloud or VPS section, and select the Public Cloud or VPS project concerned.

Open Instances in the left-hand menu and click on the name of your instance. Switch to the tab VNC console.

Step 1: Verify the network configuration
Right-click on the Start Menu button and open Run.

Type cmd and click OK to open the command line application.

cmdprompt

In order to retrieve the current IP configuration, enter ipconfig at the command prompt.

check main IP configuration

Step 2: Change the IPv4 Properties
Now you need to change the IP properties to a static configuration.

Open the adapter settings in the Windows control panel and then open the Properties of Internet Protocol Version 4 (TCP/IPv4).

change the ip configuration

In the IPv4 Properties window, select Use the following IP address. Enter the IP address which you have retrieved in the first step, then click on Advanced.

Step 3: Add the Additional IP in the "Advanced TCP/IP Settings"
In the new window, click on Add... under "IP addresses". Enter your Additional IP address and the subnet mask (255.255.255.255).

advance configuration section

Confirm by clicking on Add.

Additional IP configuration

Step 4: Restart the network interface
Back in the control panel (Network Connections), right-click on your network interface and then select Disable.

disabling network

To restart it, right-click on it again and then select Enable.

enabling network

Step 5: Check the new network configuration
Open the command prompt (cmd) and enter ipconfig. The configuration should now include the new Additional IP address.

check current network configuration