RE: Demon Email - A firewall is NOT the answer

["Mark Harrison" <Mark.Harrison@xxxxxxx>]

Roger, 

Don't know about the "non-expensive" products :-)

Personally, I wouldn't worry about POP3 at all.

Just have SMTP go to "relay box". Relaybox will relay
yourdomain.com onto the Exchange server and NOT ACCEPT any mail not for the
Exchange server.

Exchange server will send out mail directly...

I assume that Mercury can do this?

Mark

-----Original Message-----
From: Roger [mailto:roger@xxxxxxx]
Sent: 13 June 2002 18:07
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Demon Email - A firewall is NOT the answer


What about putting Mercury Mail in between Exchange and Demon? Can be set
to take mail as a client, and re-serve it locally. AFAIK Mercury can be
relay proofed, and Exchange would still be talking to a SMTP or POP3
server.

Roger Shingler

>
> Rob,
> 
> A firewall won't help, unless it also does mail relaying for you.
> 
> Port 25 needs to be open to receive email full stop. The 
> relaying issue is that port 25 should only accept email 
> either TO or FROM one of your domains. (ie - should only 
> accept email to one of your users or from one of your users - 
> the thing that Demon'
> s trying to block is your email server accepting email from 
> one third-party, and passing it on to another third-party.)
> 
> Commercial firewalls (like firewall 1) will accept plugins 
> that handle mail relaying for you, but the "turnkey Linux 
> ones" won't, AFAIK.
> 
> You need some mail relay. Linux SENDMAIL is probably the best 
> solution.
> 
> Regards,
> 
> Mark
> 
> -----Original Message-----
> From: Rob Mouser [mailto:rmouser@xxxxxxx]
> Sent: 13 June 2002 13:43
> To: Ukha (E-mail)
> Subject: [ukha_d] Demon Email
> 
> 
> Hi 
> 
> This is a little 'wide' but I feel it is relevant to us HA people.
We
> have a Demon Web account here and was infact on the verge of 
> setting one
> up for home (Fixed IP etc, ISDN, fixed cost etc.....However don't
post
> on this as its not the subject!) HOWEVER we have just had 
> external email
> banned by Demons Abuse Team due to our MS Exchange Server 
> v5.0 (Part of
> SBS Ver4.0)beeing venerable to email spammers using relay. I've
spoken
> to Demon and done some research and it appears that Exchange
Ver5.0
> cannot be protected against relay attacks! Only Ver5.5 has 
> sufficient t
> functionality to block relay use.
> 
> OK so we cannot upgrade to 5.5 (Various issues with compatibility
with
> some bespoke software supplied by another company.) (Or in effect
SBS
> v4.5) at this precise moment and so the only option is to add 
> a firewall
> to the network (25 users) anyone got any recommendations that will
do
> the trick? As long as Demon can telnet in and get refused 
> they will open
> us back up.
> 
> Yours bemused and confused.........
> 
> Many Thanks
> Rob
> Rob Mouser
> rmouser@xxxxxxx
> rob@xxxxxxx
> 
> 
> 
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