"The TLS protocol allows applications to communicate across a
network in a way designed to prevent eavesdropping, tampering, and
message forgery. TLS provides endpoint authentication and
communications privacy over the Internet using cryptography.
Typically, only the server is authenticated (i.e., its identity is
ensured) while the client remains unauthenticated.
"FTP is a very insecure protocol because all passwords and all
data are transferred in clear text. By using TLS, the whole
communication can be encrypted, thus making FTP much more secure.
This article explains how to set up ProFTPd with TLS on a Debian