SSH

SSH (Secure Shell) is a network protocol that provides a secure way to access a computer over an unsecured network. It is commonly used for login sessions, remote command execution, and other types of secure network services between two networked computers.

SSH was developed by Tatu Ylönen, a researcher from Finland, in 1995. The protocol was created in response to the security issues inherent in earlier protocols such as Telnet, which transmitted data, including passwords, in plaintext, making it vulnerable to interception. SSH encrypts the data being transmitted, ensuring confidentiality and preventing eavesdropping and tampering. The protocol operates on port 22 by default. SSH employs public-key cryptography to authenticate the remote computer and allow it to authenticate the user, if necessary. It also supports various cryptographic algorithms to secure the connection. Over the years, SSH has evolved, leading to the creation of multiple versions, with SSH-2 being the most widely used due to its enhanced security features over SSH-1. Beyond command-line tools, SSH can also be used for tunneling, forwarding, and secure file transfers, making it a versatile tool for system administrators and developers.