nanog mailing list archives

Re: Blocking MX query


From: William Herrin <bill () herrin us>
Date: Tue, 4 Sep 2012 13:22:39 -0400

On Tue, Sep 4, 2012 at 10:44 AM, Jay Ashworth <jra () baylink com> wrote:
There are no "good" subscribers trying to send email direct to a
remote port 25 from behind a NAT.

Users, like myself, running Linux on home computers and laptops; our local
sendmail-equivalents will in fact attempt direct delivery to remote SMTP MX
servers, and we generally move around enough that setting a smarthost is
semi-impractical, at least on laptops.

I'm a bad subscriber, Bill?

Okay, fair enough. There are no good users *expecting* to send email
direct to a remote port 25 from behind a NAT. There are some good
users who occasionally run slightly sloppy configurations which might
attempt spurious port 25 connections.

Good to block port 25. Not good to knee-jerk ban users whose machines
happen to poke the port once or twice.

Regards,
Bill Herrin


-- 
William D. Herrin ................ herrin () dirtside com  bill () herrin us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004


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