Secure Shell (SSH)

Wiki ▸ 🔰 Foundations ▸ Secure Shell (SSH)

Secure Shell (SSH) is a suite of software applications that implement an encrypted network protocol originally developed in 1995. Since the 90’s, SSH has been a cornerstone of remote administration. It’s one of the first and still one of the most important tools any system administrator must learn to use. The most widely known use of SSH is its application as a remote login tool. The SSH protocol provides the operator of a computer system a secure channel over an unsecured network (like the Internet) to use to access the command line of a remote system, although any network-capable service can be secured using the SSH protocol.

SSH servers are more common than you might think. Almost every computer has the capacity to function as an SSH server. The laptop you use every day can do it and, especially if you've been given a machine from your employer, it's possible that an SSH server is already running on it specifically so that the IT department can remotely administer your work computer. Many home routers have both a Web interface and a command line interface, and SSH is often what provides this command-line access.

Of course, if you can access a machine's command line over SSH, so too can anyone else. This is why securing SSH access is so critically important. An SSH server is something like the "front door" to your computer. An unsecured SSH server on a network is by far the first thing most intruders look for. These days, if you put an SSH server up on the Internet, you'll see login attempts within minutes.

Read next: Introduction to Securing (Virtualized) Secure Shell Servers ➡️