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Date: Mon, 17 Mar 1997 08:28:33 -0100
To: scott@statsci.com
From: Darius Moos <moos@webmore.com>
Subject: Re: SMTP and Firewalls 
Cc: neil@corpex.com, questions@freebsd.org
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No that's definately not true for 2.1.5
I've set up a firewall where port 25 is opened for incoming and outgoing
connections but port 113 is blocked and it works fine.

Neil, how about sending the relevant part of your rc.firewall to the list.
Maybe i can help you.

Darius Moos.

At 17:58 16.03.97 -0800, you wrote:
>neil@corpex.com (Neil) wrote:
>
>> We are using FBSD 2.1.5 with IPFW configured for a mail server. Other than
>> the obvious port 25 connections, what else must be opened in the
firewall to
>> allow SMTP 'sending'. At present we get a 'operation timed out' error as
the
>> server cannot connect ot an external server.
>
>Maybe port 113 (the "auth"/"ident") port?  I've worked in a setup where the
>systems inside the firewall were NOT setup to provide that service, so the
>firewall was set to block them.  We would get timeouts trying to get to SOME
>systems' SMTP daemons.  When we opened up the firewall to allow them through,
>the connections went through.  Our theory was that the remote system was
>getting an immediate connection refused after it was opened up, so everything
>proceeded just fine.  With the firewall blocking them, it appeared as if the
>remote systems' SMTP daemons weren't spitting out their '220' welcome message
>banners, and our systems (running smail) were hanging waiting for it.
>
>Or at least, that's how it appeared (we didn't go thru the code or trace
>anything to confirm the precise cause).  Also, note that this wasn't a 2.1.5
>IPFW firewall, but on obtained from a 3rd party (I THINK it's really a
special
>purpose Linux box).  And we were using smail instead of sendmail.  But the
>info might be useful nonetheless...
>
>Scott Blachowicz  Ph: 206/283-8802x240   Mathsoft (Data Analysis Products
Div)
>                                         1700 Westlake Ave N #500
>scott@statsci.com                        Seattle, WA USA   98109
>Scott.Blachowicz@seaslug.org
>
>