Re: [TCLUG:18672] Hidding SMTP info?

[Gabe Turner (officer) <dopp@acm.cs.umn.edu>]

Actually, you want to add the line

FEATURE(nullclient, machine-you-want-to-masquerade-as.com)

to your sendmail.mc file and then build your sendmail.cf file.  Editing your cf 
file directly is usually not a good idea, and it's so cryptic, why would you 
want to? You'll only need a few lines in the mc file:

divert(0)dnl
VERSIONID(`@(#)clientproto.mc   8.12 (Berkeley) 5/19/98')

OSTYPE(solaris2)
FEATURE(nullclient, machine-you-want-to-masquerade-as.com)

This file was derived from some of the other example mc files included with the 
sendmail source.

Gabe

> 
> There's a line in your sendmail.cf that allows you to masquerade as a particlar
> domain.  
> 
> For example, My line is set to masquerade as ardent-hacker.net rather than
> armageddon.ardent-hacker.net.  All other machines are also masqueraded as well.
> 
> goofy.ardent-hacker.net--->ardent-hacker.net
> forefront.ardent-hacker.net--->ardent-hacker.net
> and even:
> mailserver.ardent-hacker.net--->ardent-hacker.net
> 
> hope this helps.
> 
> Eric F Crist
> 
> 
> 
> 
> On Thu, 08 Jun 2000, you wrote:
> > Our network behind the firewall has grown to a point where we now have a
> > central mail server, which all client machines relay their email to. This
> > central server then works with the firewall to securely deliver the smtp
> > traffic to the Internet.
> > 
> > The problem is now there is a 'security' problem because sendmail stamps the
> > message at each hop, so our internal domain is being broadcast to the world.
> > 
> > For instance, you get
> > 
> > Received: (from tanner@localhost)
> >         by bobs.machine.real-time.com (8.10.2/8.10.2) id e587MZb06706;
> >         Thu, 8 Jun 2000 02:22:35 -0500
> > 
> > Here you can see that our internal domain is 'machine.real-time.com' and that
> > my computer's host name is 'bobs'.
> > 
> > Received: (from tanner@bobs.machine.real-time.com)
> >         by mailserver.machine.real-time.com (8.10.2/8.10.2) id e587MZb06706;
> >         Thu, 8 Jun 2000 02:22:35 -0500
> > 
> > Here you can see that our internal domain is 'machine.real-time.com' and that 
> > the central mail server is called mail server.
> > 
> > etc, etc, etc...
> > 
> > Anyone to protect this info?
> > 
> > 
> > -- 
> > Bob Tanner <tanner@real-time.com>       | Phone : (952)943-8700
> > http://www.mn-linux.org                 | Fax   : (952)943-8500
> > Key fingerprint =  6C E9 51 4F D5 3E 4C 66 62 A9 10 E5 35 85 39 D9 
> > 
> > 
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-- 
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Gabe Turner		X-President, ACM @ U of MN	     dopp@acm.cs.umn.edu

"Squeak!  Squeak!  Squeak, I tell ya Squeak!!"
					 - Ren Hoek in "The Boy Who Cried Rat!"
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