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Installing OpenSSH Using a Package Manag... > Installing OpenSSH Using a Package M... - Pg. 198

198 Chapter9·LinuxSSH Introduction In this chapter, we want to explore some of the aspects of using SSH on Linux. We want to look at how to install it, how to configure it, and what are some of the features that it provides. With its strong authentication and tight encryption, there are a wide variety of tasks that we can use it for when working with communication between machines. With a number of products on the market, we want to pick one for our examples that is well known in the Open Source community. We also want to make sure that our configuration is one that will balance security, usability, and visibility. When we have SSH up and running, we then want to explore some of the ways that an administrator or enthusiast can use the tools that come with a standard SSH distribution. Along the way, we'll talk about some tips and tricks that we can use to help manage our Linux system. Installing OpenSSH Server OpenSSH is a package that is an offshoot of the original SSH implementation, which was started in 1995. Its widespread use makes it a good choice for our Secure Shell needs, and the first step is going to be actually installing the software package. There are several ways to do this in any given Linux distribution, but the choice comes down to a simple decision between installing the software using a package manager (like apt, yum, or YAST2) or installing the software from source (that is, building the required files from the source code using a compiler). While this may seem like a simple choice, there are several points that we have to weigh when picking one over the other. Usually, when installing from source, you have a bit more control over the options that are installed and configured by default. When we want to do something non-standard with some software, such as using custom libraries or including optional functions, installing from source is the way to go. The only problem with this is that it requires build tools to be installed on the machine, and while they do not take up a lot of space, when working with a high security, low-profile server, the fewer packages that are installed, the more secure the server will be. Another important aspect to look at when picking an install method is how you want to handle updates. When using a package manager, it is easy to roll all of a system's updates into a single set of actions. When installing from source, any updates will have to be manually applied, and often times, a rebuild of the entire software package is required. With the quick turn-around of patches and fixes that are made available by the Open Source community, installing OpenSSH using a package manager is an attractive solution. Due to the large list of additional steps that installing from source requires, I'm going to recommend that we stick with the pre-packaged distribution that can be installed using the built-in package manager. Installing OpenSSH Using a Package Manager Even when using the package manager option to install our software, we still have a couple of choices to keep in mind and account for in our installation efforts. With a large number of different distributions available in the Linux community, simply providing a set of instructions for each