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spam alias

The days of being helpful in mail server dialogues are long behind us. Today, it's common not to give out any information - even taking it so far as to not identify what software the mail server is running.

But back when this was written, mail servers were more trusting and a number of "features" helped other machines identify who they should be sending mail to. Of course spammers latched on to that very quickly.

From: kbs=cusm@shady.com (Kevin Smith)
Newsgroups: comp.unix.sco.misc
Subject: Re: SPAMMERS LOOKING AT MY ALIAS FILE
Date: 12 Jan 2000 23:15:03 -0500
Message-ID: <85jjg8$bfb@shady.shady.com> 
References: <387c0c07.0@news.isdn.net>
<1b7o7sgdl2701gbnv1uj9mr20esiki7k0d@4ax.com> 

In article <1b7o7sgdl2701gbnv1uj9mr20esiki7k0d@4ax.com> jeffl@comix.santa-cruz.ca.us writes:
>On Tue, 11 Jan 2000 23:12:07 -0600, "Terry Shows"
><terry.shows@csstn.com> wrote:
>
>>I am using MMDF as my mail transfer agent.  I just got a SPAM addressed to
>>an unusual alias I have set up in my alias.n file in the table directory of
>>mmdf.   As far as I can tell, the SPAMMER either read my alias file
>>(somehow), or issued a bunch of verify requests to the SMTPD daemon until
>>they had some hits, then recorded the hits and sent the email out.
>>does anybody know how to protect from this?  My alias.n file has a lot of
>>addresses that I do NOT want spammed.
>
>telnet comix.santa-cruz.ca.us 25
>220 comix.comix.santa-cruz.ca.us Server SMTP (Complaints/bugs to:
>postmaster)
>expn root
>250 Superuser <root@comix.comix.santa-cruz.ca.us>
>expn postmaster
>250 <postmaster@comix.comix.santa-cruz.ca.us>
>expn bozos
>250 <bozos@comix.comix.santa-cruz.ca.us>
>expn jeffl
>250 Jeff Liebermann <jeffl@comix.comix.santa-cruz.ca.us>
>quit
>
>Hmmm... This was to my 3.2v4.2 SMTP which doesn't seem to expand
>aliases.  I think (not sure) that 3.2v5.0.5 will expand aliases.  If
>they manage to figure out that you're running a mailing list, and use
>the EXPN command with that mailing list, it may (not sure) belch all
>the users inside.  I'll try it when I put the RAM back into my
>3.2v5.0.5 machine.

Chances are they were just guessing unless you have 'public' on the
ALIAS line in mmdftailor for alias-n.  The 'public' keyword allows
someone connecting (as in Jeff's example) to see what the alias will
expand to.  I.e.

    ALIAS table=alias-n, nobypass, public

I think this is a checkbox in the gui configurator.  Without 'public'
expn just echos the same address back to you (with your hostname if 
you left it off) as in Jeff's example.

See 'man mmdftailor'
-- 
Do two rights make | Kevin Smith, ShadeTree Software, Philadelphia, PA, USA
a libertarian      | 001-215-487-3811  shady.com,kevin   bbs.cpcn.com,sysop
                   | dvtug.org,kevins--Deleware Valley Transit Users Group

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