SSH

SSH, or Secure Shell, is a cryptographic network protocol used for secure communication over an unsecured network. It provides a secure channel over an insecure network by using a client-server architecture, connecting an SSH client application with an SSH server. SSH is widely used for remote login and other secure network services between two networked computers.

The protocol operates on the application layer of the TCP/IP model and uses port 22 by default. It is known for its strong authentication and encryption capabilities, which make it a popular choice for secure data transmission. SSH supports multiple authentication methods, including passwords, public keys, and host-based authentication.

One of the primary uses of SSH is remote command-line login, allowing users to execute commands on a remote machine as if they were physically present. It also supports secure file transfer using protocols like SCP (Secure Copy Protocol) and SFTP (SSH File Transfer Protocol). Additionally, SSH can be used for tunneling other protocols, such as HTTP or FTP, through an encrypted connection.

SSH is available for various operating systems, including Unix-like systems, Windows, and macOS. It is open-source and has been a standard feature in many operating systems for decades. The protocol has evolved over time, with newer versions offering improved security features and performance enhancements.