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Archiver > Freepages-Help > 2008-08 > 1219187682


From: Pat Asher <>
Subject: Re: [FreeHelp] Server Move
Date: Tue, 19 Aug 2008 19:14:42 -0400
References: <c90.2d085a3b.35dc6cba@aol.com><000a01c90241$e06cb440$4001a8c0@JILLMUIR>
In-Reply-To: <000a01c90241$e06cb440$4001a8c0@JILLMUIR>


At 05:23 PM 8/19/2008, Jill Muir wrote:
>Hi Joan,
>Can you please explain 'passive transfer'? Many thanks
>
>Kind regards,
>Jill

The Wikipedia article referenced by Joan is a good one, but to
simplify even more:

FTP requires 2 open channels between your computer and the server to
which you are connected, i.e. a command channel (usually Port 20) and
a data transfer channel (usually Port 21).

Commands such as CD (Change Directory) GET (the directory listing)
and PUT (copy this file) are exchanged over the command channel. The
actual copying of directory listings and/or files occur on the
separate data channel.

PASV mode puts your FTP client in charge of the timeouts for both
channels so that a temporarily idle command channel will not timeout
and abort your connection while large files are being copied over the
data channel.

Pat


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