Learn about SSH

SSH, short for "secure shell," is intended to be a substitute for the Berkeley r-commands (RSH,rlogin, RCP), but has some additional capabilities. This document will cover the steps for setting up SSH for use, including the setup of these additional capabilities, but will not go into much detail on how SSH actually works. The official OpenSSH website answers most common questions about SSH and has pointers to other information resources as well.

One of the best reasons for using SSH is security. Everything that SSH sends across the network is encrypted. This ensures complete privacy, making it extremely difficult for anyone to intercept and record your network traffic. (However, SSH is only as secure as you make it. If you use telnet, RSH, FTP, or any other insecure protocol, that information will be visible across the non-SSH-based connection.) Add the fact that hosts change their encryption keys hourly, and you have a host-to-host communication system that’s extremely hard to beat. SSH functions much like RSH in terms of command syntax, which also makes it extremely easy to use.

One of the other great benefits of using SSH is how it handles X connections. Instead of having to manually set the DISPLAY variable on a remote host in order to use X-based software, SSH will do it for you. Also, SSH will automatically manage your ~/.Xauthority file, adding hosts and displays as necessary. This allows the user to restrict access to the local display (using the command xhost -), yet not have to bother with using the arguably cryptic xauth program to grant remote access when using X-based software on remote hosts. Starting an xterm on a remote host is as simple as typing SSH<host> .