Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 12 Sep 2006 13:28:39 -0700
From:      Chuck Swiger <cswiger@mac.com>
To:        Bill Moran <wmoran@collaborativefusion.com>
Cc:        freebsd-questions@freebsd.org, Bart Silverstrim <bsilver@chrononomicon.com>
Subject:   Re: forwarding as a gateway, logging certain traffic
Message-ID:  <B7DDE980-7DB8-4AB8-AA85-8FD89638469C@mac.com>
In-Reply-To: <20060912160830.b7a91061.wmoran@collaborativefusion.com>
References:  <7269D41C-C334-44DC-9549-ACB28F79014A@chrononomicon.com> <20060912160830.b7a91061.wmoran@collaborativefusion.com>

next in thread | previous in thread | raw e-mail | index | archive | help
On Sep 12, 2006, at 1:08 PM, Bill Moran wrote:
>> Is there some way to get the FreeBSD system to log machines using
>> port 25 without interfering with the FreeBSD machine's filtering of
>> email function?  Or at least make the traffic visible to sniffing
>> with tcpdump or wireshark or ethereal?
>
> Off the top of my head ...
> ipfw add 25 log tcp from any to any 25
> should work.  There are certain kernel configs you have to have in
> place for logging to work, though.

Better to use something like:

	ipfw add 1 log tcp from any to me 25 setup

If Bart would like to use tcpdump for the same purpose, consider  
running something like:

	tcpdump -nt 'port 25 and (tcp[tcpflags] & tcp-syn != 0)'

-- 
-Chuck




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?B7DDE980-7DB8-4AB8-AA85-8FD89638469C>