About a month and a half ago I grew so frustrated by the boneheaded way that Amazon EC2 handles IP aliasing that I wrote a pretty lengthy post about the problems entailed and included a small program that would fix those problems.
Amazon provides some pretty productive documentation for some types of users. There is help available for you if you are any one of the following:
- You are willing to pay for a new ENI to support a second IP address
- You are multihoming / load balancing
- You want to use "Amazon Linux" and install their ec2-net-utils
But, if you want to just add a second IP address to a pre-existing Linux server, you are pretty much screwed. Well, you were screwed. Now you can install my program - aliaser - as a service and it will route additional IP addresses for you without the need for an extra ENI.
I've uploaded aliaser to Github - it includes a shell script and a .service file, as well as some very easy-to-follow instructions for how to install the script to run at boot. I've also included a link to instructions on how to get your secondary IP from Amazon, which I went through in my first blog post and is a pre-requisite for installing aliaser.
NOTE: this service is built for Red Hat Enterprise Linux / CentOS version 7 using systemd. I haven't tested it with installs using initd; the .service file would not work, obviously, but could be replaced with a fairly simple init script. I might get around to adding one for initd fans, but odds are good if you are still using initd its because you are already pretty familiar with writing an init file yourself and this would be a very simple one.
I also haven't tested aliaser with any releases other than 7.1 - so buyer beware. It would be cool to get something working for Gentoo and other operating systems.
Anyone is welcome to use aliaser for any purpose. You're welcome to add it into other software, yadda yadda yadda. If it helps another admin out of a bind, I would be happy :)
Monday, September 28, 2015
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