Passive FTP

w^rl0rd

Can someone give a simplified explanation of the difference between Passive and Active FTP?

Webmaster

Passive FTP enables your local software set up the FTP connection rather than requesting the remote server to set it up.

w^rl0rd

I see. So the client starts the session on the server's FTP command port, port 21, and the server tells the client to pick an FTP data port. Right?

Webmaster

I'm not sure if I mentioned this before, but I always love the detail in your questions, it always makes me think twice

In active FTP the server initiates the data connection to the default client's data port which is 20. In passive FTP the client initiates the data connection to a random port specified by server.

In both Active and Passive FTP the client initiates the control connection to port 21 on the server (kinda logical), but only in Passive FTP the client initiates the data connection.

I hope this helps!

w^rl0rd

Absolutely. It sounds like Passive FTP could create a headache for a paranoid Server admin.

I found a pretty detailed article here too:
http://slacksite.com/other/ftp.html

Thanks Webmaster.

Webmaster

Your most welcome.

And thanks for the link, seems like an article that deserves it's title.

I just wanted to add, that for CompTIA's Net+ exam the FTP data port is 20. They usually don't go beyond the basics.