Adding IP Aliases to Your Server

Select your operating system to configure IP aliases:

• Ubuntu/Debian
• CentOS/RHEL
• Windows Server

For Linux (Ubuntu/Debian)

1. Edit Network Configuration

sudo nano /etc/network/interfaces

2. Add IP Alias Configuration

Add the alias IP configuration under the primary network interface configuration. For example, if your primary interface is eth0:

auto eth0
iface eth0 inet static
    address <PRIMARY_IP>
    netmask <PRIMARY_NETMASK>
    gateway <GATEWAY>

auto eth0:0
iface eth0:0 inet static
    address <NEW_IP_ADDRESS_1>
    netmask 255.255.255.255

auto eth0:1
iface eth0:1 inet static
    address <NEW_IP_ADDRESS_2>
    netmask 255.255.255.255

3. Restart Networking Service

sudo systemctl restart networking

For Linux (CentOS/RHEL)

1. Create Network Script for IP Alias

Create a new network script for each IP alias. For example:

sudo nano /etc/sysconfig/network-scripts/ifcfg-eth0:0

Add the following configuration for the first alias:

DEVICE=eth0:0
BOOTPROTO=static
IPADDR=<NEW_IP_ADDRESS_1>
NETMASK=255.255.255.255
ONBOOT=yes

Repeat the steps for the second alias by creating another script:

sudo nano /etc/sysconfig/network-scripts/ifcfg-eth0:1

Add the following configuration for the second alias:

DEVICE=eth0:1
BOOTPROTO=static
IPADDR=<NEW_IP_ADDRESS_2>
NETMASK=255.255.255.255
ONBOOT=yes

2. Restart Network Service

sudo systemctl restart network

For Linux using systemd-networkd

1. Check if systemd-networkd is enabled

Ensure that systemd-networkd is the network manager in use.

sudo systemctl status systemd-networkd

If it is not enabled, enable it:

sudo systemctl enable systemd-networkd
sudo systemctl start systemd-networkd

2. Edit Network Configuration

Open the network configuration file. This file may vary, but a common default is /etc/systemd/network/50-default.network.

sudo vim /etc/systemd/network/50-default.network

3. Add IP Aliases

Add or modify the configuration to include the primary IP and the alias IPs. Here is an example configuration:

[Match]
Name=eth0

[Network]
Address=<PRIMARY_IP_ADDRESS>/<PRIMARY_NETMASK>
Gateway=<GATEWAY>

[Address]
Address=<NEW_IP_ADDRESS_1>/32

[Address]
Address=<NEW_IP_ADDRESS_2>/32

4. Restart systemd-networkd

sudo systemctl restart systemd-networkd

Example Configuration

Here's an example configuration assuming your primary interface is eth0, your primary IP address is 192.168.1.10, and you're adding 192.168.1.11 and 192.168.1.12 as aliases:

[Match]
Name=eth0

[Network]
Address=192.168.1.10/24
Gateway=192.168.1.1

[Address]
Address=192.168.1.11/32

[Address]
Address=192.168.1.12/32

For Windows Server

1. Open Network Connections

Go to the Control Panel, navigate to Network and Sharing Center, and click on Change adapter settings.

2. Configure IP Alias

Right-click the network adapter connected to the network and select Properties. Select Internet Protocol Version 4 (TCP/IPv4) and click Properties. Click Advanced to open the Advanced TCP/IP Settings dialog. In the IP Addresses section, click Add and enter the new IP address and subnet mask. Repeat the process for each additional IP you want to add. Click OK to close each dialog box.

3. Verify Configuration

ipconfig

Verify Configuration

Check IP Configuration

Verify the new IP addresses are configured.

ip addr show eth0

Ping the New IPs

From another machine, try to ping the new IP addresses to ensure they are reachable.

Conclusion

By following these steps, you can successfully add additional IP addresses as aliases on your server. This configuration can be useful for various purposes, such as hosting multiple websites or services on different IP addresses.