March 22, 2021
Secure Shell or SSH is a cryptographic network protocol that allows users, mainly system administrators, to control, maintain, and modify remote servers over unsecured networks.

The protocol also provides extra functionality such as encryption mechanisms, client/server communications, and network /application management.

SSH was specifically designed to replace insecure protocols such as Telnet, which rendered information in the form of plain text.

How It Works

Just like most of its predecessors rlogin (remote login), Telnet, and rsh (remote shell), SSH supports similar functions such as terminal session remote access, remote copy, and file transfer.

There are many uses of SSH, but we will demonstrate how it works by using a Unix, Windows, or Mac system.

Since Secure Shell is built upon the client-server model, the first step usually involves initiating a session between the client and the server.

Most of the configuration is done from the SSH client. Public Key cryptography is then utilized in verifying the SSH server.

Hashing algorithms and symmetric key encryption are used in the maintenance of data transmission which is in the form of ciphertext. This mitigates attacks that operate by packet hijacking.

Different ciphers are used in SSH the most popular being Blowfish and AES. These may vary between applications.


Despite its popular use being logging into and executing commands to a remote machine, SSH has critical uses such as in cloud computing. It also plays a critical role in access management and identity management.

SSH keys can also be used to achieve server access automation.

SSH Implementation

SSH is an open-source protocol and comes in-built with most computing platforms. You can therefore use SSH from your device (client) and execute commands through a command line or GUI.

Unlike Linux and MacOS X which have inbuilt SSH capabilities, some platforms will need you to download third-party applications to use them.

One good application you can use is PuTTY, which is available for macOS, Windows, and UNIX/BSD.

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