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November 29, 2007
Active Vs. Passive FTP
Dealing with an issue in a fire-walled environment or a problem with connectivity?
We found this basic walk-through definition of Active vs. Passive FTP.
It's a bit on the technical side, but hopefully is helpful.
Click here to view the article on Active vs. Passive FTP
Summary:
"Active FTP is beneficial to the FTP server admin, but detrimental to the client side admin. The FTP server attempts to make connections to random high ports on the client, which would almost certainly be blocked by a firewall on the client side. Passive FTP is beneficial to the client, but detrimental to the FTP server admin. The client will make both connections to the server, but one of them will be to a random high port, which would almost certainly be blocked by a firewall on the server side.
Luckily, there is somewhat of a compromise. Since admins running FTP servers will need to make their servers accessible to the greatest number of clients, they will almost certainly need to support passive FTP. The exposure of high level ports on the server can be minimized by specifying a limited port range for the FTP server to use. Thus, everything except for this range of ports can be firewalled on the server side. While this doesn't eliminate all risk to the server, it decreases it tremendously."
Posted by Erik Small at November 29, 2007 09:39 AM digg this add to del.icio.us add to My Web Furl this page
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