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To: Nate Williams <nate@mt.sri.com>
cc: hackers@FreeBSD.ORG
Subject: Re: FTP protocol questions (non-passive mode) 
In-reply-to: Your message of "Wed, 27 Aug 1997 16:34:07 MDT."
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Date: Thu, 28 Aug 1997 00:46:01 +0100
From: Brian Somers <brian@awfulhak.org>
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> Can anyone explain to me the FTP 'Data' channel protocol?
> 
> As I understand it, the client creates a socket, and the server binds to
> it, and then the 'DATA' is sent to it.  How does the server know which
> port to bind on the client?  Is there something obvious I don't
> understand as to why they couldn't use the original 'channel'?
> 
> Thanks for any help!

The client, after creating a listening socket, sends a "PORT" command 
describing the IP & port that the server should bind to.

It's done this way because it's easier.  Ftp was designed way before 
things like firewalls made it a pain in the ass.

> 
> Nate

-- 
Brian <brian@awfulhak.org>, <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour....