Mailinglist Archive: opensuse-edu (75 mails)

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Re: [suse-linux-uk-schools] SendMail Relays
  • From: giles@xxxxxxxxxxxxxx
  • Date: Tue, 2 Jul 2002 08:22:13 +0000 (UTC)
  • Message-id: <E17PIyl-00076e-00@xxxxxxxxxxxxxxxxxxxxxx>
On 2 Jul, Gareth Edmondson wrote:
> Hi there,
>
> With our school due a broadband upgrade within the next few months, we have
> decided to begin preparations by trying to sort out our problematic
> mailserver.
>
> We are currently running INet Easymail V5.09 on a WindowsNT4 machine. This
> machine also doubles as our Network BDC. Because of this it has been placed
> on our school private IP range (192.168.4.x) - this makes sense I do
> believe. We have been having trouble getting EasyMail to receive mail
> through our SuSELinus Firewall box. It has caused us major headaches over
> the past two months, and we simply cannot get it sorted - even though all
> the rules (IPTables) are correct.
>
> Our service provider has suggested that we move our mail server to a public
> IP address to it is directly accessible from the outside and thus does not
> have to go through any firewalls. Thus we decided upon setting up a SendMail
> box which would contain two network cards - one public and one private (on
> the 4.x range). Mail would then arrive on the public address, where Sendmail
> would route it to our IMail server on NT.
>
> Does this make sense to you Guru's out there? Is this setup possible?
>
> At the moment, I have no idea how to go about this - what I do know is that
> I need minimum disruption to the network whilst I learn about Sendmail and
> relaying through.
>
> Is it possible to receive mail in Sendmail and relay it to a private IP
> address (which will me 192.168.4.3)? Should I have two network cards in the
> Sendmail machine - one public, one private?
>
> Any help is gratefully received,
>
> Gareth Edmondson
> ICT Teacher
> Ysgol Gyfun Gwyr
> Swansea
>
>
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>

It is possible to receive mail on a server with a private IP but only
indirectly. I have one school here receiving mail on NT under RM connect
(sorry). All the mail for the school servers is received initially by a
mail hub which passes it to a firewall and on to the school mail server
via address translation. In the case of the NT box it is initially
received by a linux server which passes mail for a subdomain to the NT
box. The whole chain is SMTP. For sendmail this is achieved using the
mailertable option (stored in /etc/mail/)

I don't know if it this scenario is appropriate for you. It depends on
your ISP and how the DNS for your domain is setup. The initial
reception of mail from the 'net does require a public IP address - mail
is sent to the server specified in the MX record of the DNS for that
domain, which must be available from anywhere on the net. Does your SuSE
firewall have a real IP address? Where in your network is address
translation (masquerading) done?

If this is useful and you want any more detail about how it works here
let me know.

HTH

____________________________________
Giles Nunn - ISP Officer
Carms Schools ICT Development Centre
Tel: +44 01267 228277 Fax: 228275
____________________________________


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