[Exim] Home network mailhub

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Author: Harry Putnam
Date:  
To: exim-users
Subject: [Exim] Home network mailhub
Setup: OS Debian Linux (woody)
       exim 3.34
General info: 4-5 home machines behind a hardware firewall
              One machine to be mail server for home network


I'm attempting to setup a small home network mail machine that does
this:

1) Retrieve mail from several POP accounts
2) Deliver to its local spool
3) Provide POP3 (or imap) access to all machines on home lan.
4) Be the smtp relay server for all home machines, sending outgoing
mail on to my ISPs smtp machine.

I have most of this in place, running `popa3d' as pop server.

What I did to test this was, first have pop3 server working on the
proposed mail hub (debian machine). I already have successfully sent
mail from a windows machine on the lan, thru the smtp outgoing debian
box, to my ISPs' smtp machine and successfully reteived it using that same
windows machine, again thru the debian box.

So the basics are in place and working. I didn't like the way headers
came out, not sure if it really matters, but I think it isn't rfc
compliant this way. I don't think my local private network addresses
should be leaking onto the internet. (I'll show an example below).

Here are some sample headers, that I think are possibly wrong. Making
no claims to rfc knowledge but I down't think hidden local machine
addresses should be showing up here.

I hoped some posters here would have a better idea how to set this up
so my local addresses are not in the headers. Or at least know if
this in keeping with rfc guidelines.

Stats on the example message headers below:
 1) This message was sent from a windows machine on the local lan
    (satwin.local.lan 192.168.0.7)


 2) Routed thru the debian box (expi.local.lan 192.168.0.8)
    to mail.dslextreme.com (ISP smtp machine)


 3) Retrieved via fetchmail on expi 192.168.0.8 (debian machine)
    to /var/mail/dh from mail.dslextreme.com (pop server)


 4) Retrieved from there by the windows machine mail client on
    satwin (192.168.0.7) by user dh


dslextreme.com is my ISPs' domain

Starting with the Received header furtherest down in the message
as 1. I see seven places where my local private network addresses are
shown.

I'm no rfc expert or even apprentice, but I don't think my local lan
addresses should be present on internet mail. These are not legal
addresses, in the sense they can be tracerouted or pinged, from the
internet.

I don't think those addresses should leak out onto the internet
where they may be taken for legal (domain owned) addresses.


Return-path: <dh@???>
Envelope-to: dh@localhost

[Note: 7 local address shown]
Received: from localhost ([127.0.0.1] ident=dh)
    by expi.local.lan with esmtp (Exim 3.34 #1 (Debian))
    id 16mgNO-0000y4-02
    for <dh@localhost>; Sun, 17 Mar 2002 11:31:30 -0800


Received: from mail.dslextreme.com [66.51.205.14]
    by localhost with POP3 (fetchmail-5.9.8)
    for dh@localhost (single-drop); Sun, 17 Mar 2002 11:31:30 -0800 (PST)


[Note: 6 local address shown]
Received: from expi.local.lan (adsl-66.51.210.228.dslextreme.com [66.51.210.228])
    by mail.dslextreme.com (8.12.2/8.12.2) with ESMTP id g2HJTGCj015065
    for <dh@???>; Sun, 17 Mar 2002 11:29:17 -0800


[Note: 5 local address shown]
Received: from localhost ([127.0.0.1] ident=dh)
    by expi.local.lan with esmtp (Exim 3.34 #1 (Debian))
    id 16mgKc-0000xM-00
    for <dh@???>; Sun, 17 Mar 2002 11:28:38 -0800


Received: from mail.dslextreme.com [66.51.205.14]
    by localhost with POP3 (fetchmail-5.9.8)
    for dh@localhost (single-drop); Sun, 17 Mar 2002 11:28:38 -0800 (PST)


[Note: 4 Local address displayed]
Received: from expi.local.lan (adsl-66.51.210.228.dslextreme.com [66.51.210.228])
    by mail.dslextreme.com (8.12.2/8.12.2) with ESMTP id g2HJOVCj013852
    for <dh@???>; Sun, 17 Mar 2002 11:24:32 -0800


[ Note: 3 Again, the local address is shown
Received: from localhost ([127.0.0.1] ident=dh)
    by expi.local.lan with esmtp (Exim 3.34 #1 (Debian))
    id 16mgG1-0000wa-00
    for <dh@???>; Sun, 17 Mar 2002 11:23:53 -0800
Received: from mail.dslextreme.com [66.51.205.14]
    by localhost with POP3 (fetchmail-5.9.8)
    for dh@localhost (single-drop); Sun, 17 Mar 2002 11:23:53 -0800 (PST)


[Note: 2 More local addresses]
Received: from expi.local.lan (adsl-66.51.210.228.dslextreme.com [66.51.210.228])
    by mail.dslextreme.com (8.12.2/8.12.2) with ESMTP id g2HJNeCj013611
    for <dh@???>; Sun, 17 Mar 2002 11:23:40 -0800


[Note: 1) My local network addresses are visible here]
Received: from satwin.local.lan ([192.168.0.7] helo=SATELLITE)
    by expi.local.lan with smtp (Exim 3.34 #1 (Debian))
    id 16mgFB-0000wN-00
    for <dh@???>; Sun, 17 Mar 2002 11:23:01 -0800
From: Harry Putnam <dh@???>
Subject: AGENT_KEYS test.4
Date: Sun, 17 Mar 2002 11:22:46 -0800
Organization: mobile
Message-ID: <1OyUPDAvjsFymkCmbmkiyE3rFmOQ@???>
X-Mailer: Forte Agent 1.6/32.525
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="--=_Bu2UPAgUcAw5fAzwlQFD+Vlm6wKO.MFSBCHJLHS"
X-UIDL: LT~!!~5F!!@;%#!m@L!!
Status: U