openssh

SSH (Secure Shell) is a program for logging into a remote machine and for executing commands in a remote machine. It is intended to replace rlogin and rsh, and provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections and arbitrary TCP/IP ports can also be forwarded over the secure channel.

OpenSSH is OpenBSD's rework of the last free version of SSH, bringing it up to date in terms of security and features, as well as removing all patented algorithms to separate libraries (OpenSSL).