Fake MTA

[Joseph Norton]

Hi listers:

Recently, I brought up an old version of Linux on my 486 just to see what
it was like.  I telneted into it and everything went all right.  That is,
until, someone started scanning the ports on the old system and found out
that port 25 was open.  You can guess what happened...  They immediately
tried (and as far as I know succeeded) to send out a piece of spam which
my older version of sendmail happily forwarded.  Now, before you tell me
that later versions of sendmail (I believe 8.9 and after) do not allow
relaying by default and that I shouldn't have been playing around with
older software, let me explain the reason for relating this.

The experience got me to thinking something along these lines.

Do any of you know if anyone has written a sort-of fake mta (mail
transport agent) that looks like sendmail or some other mail program that
just accepts all mail and stores (or dumps) it without sending it along?
Might be interesting to leave it running on an older machine just to make
some spammer think he's sending out successful messages when you're really
dumping them to /dev/null or something like that.  Also might be
interesting to see what you can pick up (though sorting through that mess
probably wouldn't be worth the trouble).

Any thoughts?