Understand ACTV mode and the PORT command

Question

I'm the part time FTP server administrator (with no real full-time admin). We currently only allow ACTV mode connections. Some of our clients have had issues with this but for the most part they've been ok using ACTV. For the few who aren't, we've been able to push the data over to their servers from ours. there is one client in particular however who is currently having trouble. He is using file-zilla and issuing a PORT command. First, does using the PORT command imply that you are in ACTV mode? Second is there a way in FileZilla to explicitly change to ACTV mode? Thanks for the help, _Ramy

Answer 1

Active mode requires the PORT command. PORT is what tells the server where to connect to on the client in order to open the data channel.

Active FTP breaks when the client is behind NAT, hence Passive is the preferred default in most situations where FTP is used. It is strongly preferable to not use FTP and switch to SFTP.