[114635] in North American Network Operators' Group
Re: MX problems
daemon@ATHENA.MIT.EDU (Jay Hennigan)
Tue May 19 19:22:12 2009
Date: Tue, 19 May 2009 16:19:48 -0700
From: Jay Hennigan <jay@west.net>
To: Polar Humenn <polar.humenn@gmail.com>
In-Reply-To: <f9a0d0460905191544n5bdc7ad0lb53c4dc68b356086@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Polar Humenn wrote:
> I'm in Syracuse NY, and I'm having problems getting sendmail to get to MX
> servers, with the errors of "No Route to Host" or "Connection timed Out".
> Apparently this is been happening for over 5 days. I can send mail within
> Syracuse University, but as soon as I venture out nothing. Traceroute seems
> to loose it after about the 9 or 10th hop.
>
> It seems that I can get to almost any website, but tracerouting or pinging
> these MX servers is not happening.
>
> Is there anything going on, or at least something that started 5-7 days ago?
>
> I find the same problem from within Syracuse Univeristy to my RoadRunner
> account at home (which does not pass through the university routers). I only
> noticed it from the university since thats where I usually send my email
> through. Like I would no have been able to post to this list
Many ISPs, especially for residential and similar customers, filter TCP
25 outbound and provide a "smart host" MTA on net for their customers to
use for sending outbound mail. This is an anti-abuse measure.
If an offnet MX host returns pings but times out when you telnet to port
25, you're probably being filtered (somewhat) locally.
--
Jay Hennigan - CCIE #7880 - Network Engineering - jay@impulse.net
Impulse Internet Service - http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV
