A file transfer Protocol and used by the scp(1) utility, which is designed to be a secure replacement for rcp(1) without its weaknesses. rcp(1) uses a completely unencrypted connection which allows anyone on the network to evesdrop on both the credentials as well the contents of files being transferred. In contrast, scp(1) uses a SSH tunnel. This also allows you to use an authorized_keys file (see SSHKeys) – which is more convenient than rcp(1) and more secure. What else could you want?