In my last post, I gave you a glimpse to runlevels, their purpose, and how they affect the overall operation of your box. Today, in this post, I am going to dig deeper into runlevels, as well as manipulating services in specific runlevels. I’m going to show you why you want to do this, as well as how. We’ll learn about the ‘update-rc.d’ command mainly, spending a great deal of time with examples and demos.
As many of you are probably already aware, I’m a Linux trainer for Guru Labs. We do all Linux training, including Red Hat, Fedora, SUSE, and others. If your company is looking for good, solid Linux training, Gurus at Guru Labs are the cream of the crop, and I’d highly recommend it. I’ve been doing a lot of Red Hat training lately, and during the training, I cover how to manage services on a Red Hat system. Lately, I’ve been meaning to translate this over to Ubuntu, and put it in a series of posts. As a result, the subject of this post is all about learning runlevels, and how to manage services effectively, such as Apache, Squid, SSH, and so on, in Ubuntu. So, let’s get started.
Your Debian / Ubuntu Linux box security depends upon access to system services (one of many aspects). For example, you may need to provide a web server (Apache service) to serve web pages. However, if you do not need use a service, you should always turn off all unused services to avoid exploits.