SSH (the Secure SHell) is a secure replacement for many UNIX tools like telnet, ftp, rsh, rcp, rlogin, rexec, and many more, which have proven to be insecure, even if most UNIX systems still use them by default, and even Microsoft has now begun to integrate those into his operating systems.
I'll talk about the most used one, and free OpenSSH, which has been created by the OpenBSD team. OpenSSH implements both sides of the communication: client and server.
« OpenSSH is a FREE version of the SSH protocol suite of network connectivity tools that increasing numbers of people on the Internet are coming to rely on. Many users of telnet, rlogin, ftp, and other such programs might not realize that their password is transmitted across the Internet unencrypted, but it is. OpenSSH encrypts all traffic (including passwords) to effectively eliminate eavesdropping, connection hijacking, and other network-level attacks. Additionally, OpenSSH provides a myriad of secure tunneling capabilities, as well as a variety of authentication methods. »
This article was first written in July 2003 for the BeezNest technical website (http://glasnost.beeznest.org/articles/41)