[62673] in North American Network Operators' Group
Re: Providers removing blocks on port 135?
daemon@ATHENA.MIT.EDU (David B Harris)
Sat Sep 20 18:55:15 2003
Date: Sat, 20 Sep 2003 18:51:50 -0400
From: David B Harris <david@eelf.ddts.net>
To: nanog@merit.edu
In-Reply-To: <046801c37fc5$b095ad70$152ea8c0@magpie>
Mail-Copies-To: nobody
Errors-To: owner-nanog-outgoing@merit.edu
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On Sat, 20 Sep 2003 23:22:34 +0100
"Ray Bellis" <rpb@community.net.uk> wrote:
> What we do have though are (optional) *inbound* filters that make sure
> no-one can connect to their privileged ports over TCP/IP, and a mandatory
> filter that says only our network can deliver to their SMTP service.
>
> We don't get problems with open-relays on dialups. We didn't have any
> problems with MS-Blaster on dialups either...
I would suggest instead that you have mandatory sending via your relays,
and allow inbound connections to port 25.
Sympatico, last I checked, didn't have any restrictions until you
tripped off their alarms, at which point you needed to configure your
smtpd to send mail via their relays. If they continued spewing copious
amounts of spam, cut them off entirely until they fix their
configuration.
There are a couple of pluses to this type of setup; people like me who
have dozens of (required) email addresses can forward them all to their
home machine. Some of my family also much prefer this even though
they've only got one or two email addresses. It also ensures that they
can't send spam directly no matter what the source; blocking inbound
connections will certainly stop open relays, but it won't stop trojans
and worms and whatnot that are really just spamware. (Note that I
consider spamware included in other applications and hidden from the
user "trojans.")
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