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Date:      Wed, 17 Oct 2001 21:11:03 +0200
From:      "Dave Raven" <dave@reason.za.org>
To:        "Weldon S Godfrey 3" <weldon@excelsus.com>, <freebsd-questions@FreeBSD.org>
Subject:   Re: Squid/IPNat FTP.
Message-ID:  <006c01c1573f$7bf51520$3400a8c0@DAVE>
References:  <20011017134106.O59186-100000@joule.excelsus.com>

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Yes quite. That explains it all actually.
As is says opening ASCII mode (or whatever) it stalls, as if its been
suddenly blocked.

Thanks all,
You've been most helpfull.



----- Original Message -----
From: "Weldon S Godfrey 3" <weldon@excelsus.com>
To: "feenikz" <demi@god.za.net>
Sent: Wednesday, October 17, 2001 7:47 PM
Subject: Re: Squid/IPNat FTP.


>
> I am not too familar with ipfilter, i am more familar with ipfw.
>
> But, the usual problem is that, even if you have an "established" rule for
> any connection.  That will only catch the port the ftp connection was
> inititaed on (which is port 21).  When someone starts a transfer (which
> even an "ls" is considered an ACSII file transfer in ftpland, it sends the
> data back on port 20 (ftp-data).  Since this not the port which the
> connection was established on, the data gets dropped at the firewall.
>
> In the pass, I have opened port 20 to allow any 20 to come in.  This can
> have drawbacks if someone on the internal lan has placed something evil at
> that port and therefore creates a possible hole to get into the LAN.
> Although typically, leaving port 20 open isn't too bad since no computer
> on your network should be expecting a connection on port 20 except an ftp
> client.
>
> The best way to solve your problem is to setup an ftp proxy on your
> firewall box and have people proxy through that.
>
>



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