15.1. The File Transport Protocol
FTP uses a client server architecture to transfer files using the TCP network protocol. Because FTP is an older protocol, it uses unencrypted username and password authentication. For this reason, it is considered an insecure protocol and should not be used unless absolutely necessary. A good substitute for FTP is sftp from the OpenSSH suite of tools. For information about configuring OpenSSH, refer to the chapter titled OpenSSH in Red Hat Enterprise Linux System Administration Guide. For more information about the SSH protocol, refer to Chapter 20, SSH Protocol.
However, because FTP is so prevalent on the Internet, it is often required to share files to the public. System administrators, therefore, should be aware of the FTP protocol's unique characteristics.