FileZilla Server is a reliable FTP server.
- almost unlimited number of users
- multi-threaded engine
- runs as service under Windows NT4, 2000 and XP
- still supports Win95
- anti fxp / bounce attack filter
- secure password storage (as MD5 hash)
- real-time user/group management
- all options can be set at runtime, there’s no need to take the server offline
- no-transfer timeout which can kick idle users which use basic keep alive systems
- Server and user/group speed limits based on rule sets.