FTP passive or active

slayerhawk · ‎10-24-2007

Hi all. I have an issue where a 1750 using IOS 12.1.3(XT2). I have client software on the LAN side that creates an FTP connection, authenticates, then disconnects without transferring any files.

I called the company and they stated that it could be an ftp "active/passive" issue. Can anyone shed any light on why I would need to make adjustments to my config?

a.cruea1980 · ‎10-24-2007

Because active FTP connections use a random port for data transfer, but passive uses port 20, if I remember correctly.

It would probably be wiser to make the clients use passive FTP than to change your router around to try and get connections through.

Frank Hoeben · ‎10-25-2007

You've got it the wrong way around.

PASV uses a random >1024 port, while non-passive uses port 20 for data connections.

BOTH can be a pain to setup if the FTP server is unaware of being behind NAT.

cjnwodo · ‎10-26-2007

Hi,

Here's a link to help with the description of active and passive FTP:

http://www.cisco.com/web/about/ac123/ac147/ac174/ac199/about_cisco_ipj_archive_article09186a00800c85a7.html

slayerhawk · ‎11-06-2007

Has anyone made this work? The clients on the LAN side use an active ftp session. I have used an access list that allows all tcp, ip, and udp to the host ip address.

a.cruea1980 · ‎10-31-2007

Ooooooooops. Thanks. :)