SSH stands for "secure shell" and refers to both the protocol and the program itself. The OpenSSH [1] program suite, developed by the OpenBSD project, offers users a free SSH alternative with everything necessary to use encrypted connections on many operating systems: command-line tools for working on remote machines, the ability to execute programs remotely (including graphical applications via X11 forwarding) or to tunnel Internet services via SSH (and thus secure a connection against sniffing), tools for secure file copying, and more. Table 1 gives you an overview of the major applications.

OpenSSH is a mainstay of any recent Linux distribution, so installation is quite straightforward. Most systems offer separate packages for the client and the server. Although the client typically is pre-installed, setting up the server often is necessary if you want to access your Linux computer via SSH from another machine. Searching for openssh in your package manager should reveal the correct package.

In this article, I will investigate the use of hostkeys, how to verify hostkey fingerprints, how to manage private keys with the SSH agent (including temporary management), how to tunnel SSH connections with the integrated SOCKS proxy, and how to transfer data interactively via secure ftp.

[...]