[Mimedefang] Starting all over to kill invalid users

Steve Campbell campbell at cnpapers.com
Fri Jul 7 09:55:50 EDT 2006


----- Original Message ----- 
From: <WBrown at e1b.org>
To: <mimedefang at lists.roaringpenguin.com>
Sent: Friday, July 07, 2006 8:36 AM
Subject: Re: [Mimedefang] Starting all over to kill invalid users


> Steve Campbell wrote on 07/06/2006 05:11:25 PM:
>
>> 2).   It would be nice to be able to do the md_check_against_smtp_server
>
>> using an IP address as opposed to a hostname for the variable
> $rcpt_host.
>> Looking at my logs, I see where it checks the IP defined by my DNS for
> the
>> $rcpt_host, even though I have a different internal address defined in
> my
>> host file (much like sendmail does if you don't put square brackets
> around
>> the IP), so I guess it is working correctly. Is there anyway to force
> the
>> function to use an alternately-defined IP for a hostname?
>
> GAH!!! Hard coding IP addresses whenever not absolutely necessary is one
> of my pet peeves.  What happens when that server gets moved to a different
> VLAN and the address changes.  Odds are that someone will forget the
> numeric address was hard coded into your filter and the whole thing stops
> working.  Remembering to update it once in the DNS is a no brainer.

I may be overthinking this, but I don't have an internal DNS machine set up 
yet. I would like to keep this all on my internal network to avoid the 
firewalls, DNS, and everything else it would require. It has to make it a 
little faster also.

Using DNS is not really a problem, but it would be a little nicer to keep it 
inside (which is also on a faster LAN).
>
> Why would you want to use IP instead of name?  Don't your users resolve
> the mail server's name via DNS anyways?  I know that in most POP/IMAP
> clients you do, as well as Lotus Notes.  Can't speak for M$ Exchange
> though.

Yes they do to some degree, but this function works on incoming mail, I 
believe. Our users send to the specific machine they require based on how 
their client is set up. They require DNS here. If they are sending mail to a 
user in the same domain, it is delivered locally. It they send to one of our 
other domains, it is relayed based on how sendmail is set up to deliver mail 
to that domain, which is sent on our internal network without further DNS. 
Other users from outside our domains send to MX machines. I just want to use 
this for the spamming dictionary attacks, which most of our local users 
don't usually try to do.
>
> DNS was invented to do away with having to maintain hosts files.
>
> Can you explain the scenario better, we might understand why you might
> need to use IP address, but I'm sceptical of the need

MD will not be running on the actual mailbox server, just the MX machines. 
Once local (by definition here means "one of our domains") mail reaches a 
server, it will not see MD. Only non-local incoming mail will ever meet up 
with MD.

Hope the above helps and thanks. I hope I said all of that properly.

Steve 





More information about the MIMEDefang mailing list