North American Network Operators Group
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Re: Misguided SPAM Filtering techniques

  • From: Owen DeLong
  • Date: Tue Oct 23 20:32:28 2007

On Oct 23, 2007, at 1:48 PM, Christopher Morrow wrote:

On 10/23/07, Jack Bates <[email protected]> wrote:
I really don't get it. While I understand with tcp/25 blocking, there is
absolutely no reason to block tcp/587. If credential's are being hijacked, it is 

morrowc$ telnet mail.ops-netman.net 26
Trying 71.246.230.124...
Connected to mail.ops-netman.net.
Escape character is '^]'.
220 A host is a host from coast to coast... Hosty-host ESMTP...

why don't people just run a new version of their MTA on a port
not-filtered?? The simple fact is that port-25 filtering does help, it
does also seem to piss off some portion of 'smart folks' (power users,
whatever you choose to call them). So, being smart, just work your
box(es) such that this isn't a problem for you?

I want to make it clear... I don't mind people filtering either 25 or 587,
but, blocking both is highly unacceptable. Even more unacceptable
in my opinion is hijacking connections to either off to your own
man-in-the-middle attack server.

Owen

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