http://www-hera-b.desy.de/subgroup/computing/sshinst.html
Why?
Because every password you type after using rsh, rlogin, xrsh, xrlogin, telnet, or ftp is transmitted as clear ASCII text over the network. This way, any root user running a simple tool to dump the TCP/IP traffic can collect passwords. These tools come with a number of operating systems. Different from the above, sshoffers you encryption of all information transmitted in your session.
Although ssh comes with the SUSE Linux distribution, it is always a good idea to get the latest release from http://www.cs.hut.fi/ssh/ or the German mirror ftp://ftp.cert.dfn.de/pub/tools/net/ssh. As of this writing, this is ssh-1.2.26.tar.gz of 10-July-1998. The archive comes with a PGP signature.