FileZilla Server is an FTP server that supports FTP and FTP over SSL/TLS. FTP over SSL/TLS provides secure encrypted connections to the server.
Designed for Servers only, FileZilla Server supports SSL, the same level of encryption supported by your web browser, to protect your data. When using SSL your data is encrypted so that prying eyes cannot see it, and your confidential information is protected. It also supports on-the-fly data compression, which can improve the transfer rates.

It includes numerous functionalities, including:
A user connections manager in FileZilla Server — displayed along the bottom of the window — allows the administrator to view currently connected users and their uploads/downloads. At present, there are two operations the owner of the server can do to those transfers — to “kill” the client session or to “ban” the user’s IP address. This manager shows the real-time status of each active file transfer.
Support for SFTP (SSH File Transfer Protocol) is not implemented in Filezilla Server.
Download FileZilla Server (on Sourceforge.net)
More info with FileZilla Server FAQ and FileZilla project documentation