How to Add an Additional IP Address to Your Linux Server

Most Linux servers, including virtual private servers, will occur with a general public IP tackle for you to join to. Even so, the physical network card applied to have the link can guidance any variety of IP addresses. Here’s how to insert a new just one to your server.

Why Use An additional IP Address?

Obtaining various addresses is wonderful for a range of good reasons. The main reward is staying ready to have numerous purposes running on the very same port, but on diverse addresses. For instance, you couldn’t run NGINX and Apache at the very same time, as they are both world wide web servers that will need to use port 80. On the other hand, if you ran NGINX sure to one particular IP deal with, and Apache sure to an additional, you could do so with out any conflict.

In this situation of serving internet written content, you can also clear up this difficulty with a reverse proxy—a variety of net server that sits in entrance of your articles, listens on a person port, and directs written content to other locations, normally multiple different locations.

Associated: How to Set Up a Reverse Proxy With Apache

Nonetheless, possessing multiple genuine IP addresses can be a great deal simpler with no reverse proxy configuration to maintain. You only start out the services on the proper deal with, and it will hear directly on that tackle.

Multiple addresses also function really effectively with Docker, which is a instrument that can deal programs into transportable containers and run them everywhere. Having many external IPs to bind containers to will allow your server to operate lots of diverse applications effortlessly on a single device.

How Do I Get Extra IP Addresses?

There are a finite selection of community IPs left in the entire world, and most are currently allocated to web organizations. In buy to get additional, you will want to acquire or rent them from your internet hosting company. Most mainstream cloud companies will have an option for more IPs, but the set up will count on what you are utilizing.

For illustration, if you are on AWS, you probably presently have an Elastic IP Tackle for your EC2 cases. Having said that, you can just add additional Elastic IPs, at the expense of $3.65 per month for each 1.

Linked: What Are AWS Elastic IPs, and What Do They Do?

Other cloud vendors could possibly let you purchase full blocks of addresses. OVH, one particular of the most significant focused server vendors, delivers CIDR blocks of up to /24 in sizing, for a one particular-time rate.

Large corporations that want to immediately individual and command a massive amount of money of IPv4 tackle room can also invest in overall blocks right from IANA (by means of a brokerage). Having said that, this arrives at a large premium—often over $50 per address, and huge blocks value tens or even hundreds of countless numbers of bucks.

How Do Numerous IP Addresses Do the job?

Linux networking is a little weird. Every community card bodily attached to your server will demonstrate up in ip addr exhibit as a network interface like eth0 or eno1. There can also be many forms of digital interfaces, but all true connections out from the server go through a actual physical network interface.

IP addresses are different—they are not tangible factors that are linked with your server’s community interface, they are just an abstraction utilised to establish servers for routing. Your hosting supplier will get a ask for, and if it is destined for an IP handle you individual, it will be routed to your server applying the host’s routing configuration.

The key part there is that your server’s community interface will have to be configured in program to acquire that ask for. If your server does not have the tackle extra to a network interface’s config, it won’t answer. You could technically configure your server to listen on any handle, even ones you don’t own, even though it wouldn’t do just about anything.

IP addresses are allotted in blocks, represented in CIDR notation. The smallest is /32, which represents a single deal with. As the variety will get smaller, the quantity of addresses improves.

192.168../24 -> 192.168.. to 192.168..255

Relevant: What are Subnets, and How Do They Influence My Network?

Configuring Linux to Use Several IP Addresses

Linux community configuration can be tricky, and there are a number of applications out there to make it less complicated. Just one of the ideal is netplan, developed by the team driving Ubuntu. It configures community interfaces using straightforward YAML templates. It really should be installed by default on most units.

Create a new template in /and many others/netplan/config.yaml:

sudo nano /and many others/netplan/config.yaml

Then, include your configuration. Notice that this case in point is for the interface eno1, which may will need to be transformed to eth0 or a thing equivalent.

community:
    edition: 2
    ethernets:
        eno1:
            addresses:
            - 123.1.2.3/32

You can specify several handle blocks below, or solitary IP addresses as singular /32 blocks.

As soon as configured, run netplan test to test it out. If the config is defective, it will be rolled back again.

sudo netplan check out

If it will work, use the config:

sudo netplan implement

You can debug your routing by running tcpdump to screen requests despatched to an interface: