OpenSSH is a package of secure connection tools that you can use in your connections via Telnet, RCP and FTP.
You will not notice any difference, only that the connections from the moment you install this package will be secure connections. For Telnet instead of using a rlogin connection an SSH connection will be used; for RCP the SRCP connection will be used and for FTP the SFTP option will be used. In all cases the data will be encrypted, including passwords or user names.
It is a program written in open source, so you can improve it if you are capable of it or you consider it necessary. It is totally free and provides a really secure and powerful encryption mode.