[115401] in North American Network Operators' Group
Re: Is your ISP blocking outgoing port 25?
daemon@ATHENA.MIT.EDU (John Levine)
Thu Jun 18 16:19:01 2009
Date: 18 Jun 2009 20:18:49 -0000
From: John Levine <johnl@iecc.com>
To: nanog@nanog.org
In-Reply-To: <01aa01c9f04c$1d0a8820$e76ed48d@zhiyunpc>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
>I wonder which ISPs are still doing so. I know comcast has been doing
>that but they cancelled it after many complaints. It seems to be the
>same case for Verizon.
You're mistaken. Comcast most certainly does port 25 filtering,
although not necessarily on every line at every moment. So does
Verizon, AT&T, and every other large North American consumer ISP I
know.
Look, kids, it's not 1998 any more. These days outgoing traffic to
port 25 is approximately 99.9% botnet spam, 0.1% GWL, and 0%
legitimate mail. Blame the botnet herders and the vendors of cruddy
software that year after year still is full of trivial exploits. If
you can make the botnets go away, I will be happy to lead the charge
to unblock all those ports.
If it's important to you to have an unfiltered connection, pay for
business service that has a static IP, or arrange to tunnel to some
host that does.
R's,
John
