[sclug] DHCP and DNS

Ian Park ian at chalmers-park.name
Mon Apr 25 09:44:27 UTC 2005

Will Dickson wrote:
Date: Mon, 25 Apr 2005 01:38:45 +0100
From: Will Dickson <wrd at glaurung.demon.co.uk>
Subject: [sclug] DHCP and DNS
To: sclug at sclug.org.uk
Message-ID: <426C3C15.2080406 at glaurung.demon.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi all,

For various unimportant reasons, I decided it would be an idea to
migrate my LAN to DHCP. Well, it is the 21st century and all that...
Specifically, I'm running a Smoothwall Express (firewall) which inter
alia provides a DHCP server, so I thought it ought to be fairly
drool-proof to set up.

Indeed, the main DHCP bits were - set up the server, told the LAN boxes
to use it, and they got their IP addresses and DNS details from the
Smoothwall. DNS proper works fine - I can resolve addresses of machines
on the external Internet etc.

The problem is that my LAN hosts provide various services to each other,
so they need to be able to resolve each other's names. I assumed
(without, I confess, having really thought it through) that the DHCP
server would wave some kind of magic wand and make this work. However,
it doesn't.

There seem to be two possibilities here: a) this ought to work, and I've
cocked up somewhere; b) I'm asking for the moon on a stick, and if I
want this to happen I'm going to have to put in some actual effort.

Can anybody tell me which of these is closer to the truth?


It sounds as though you have a setup very similar to mine, Will - I have 
a Smoothwall box, with 2 desktop PCs (one Windoze 2K, one Debian Sarge) 
and my wife's Windoze XP laptop working to the network hub on the 
Smoothwall Green interface.

As I understand it, the Smoothwall box runs dnsmasq to do local DHCP and 
a caching DNS service, and it *should be* possible to get dnsmasq to do 
the local DNS lookup for the machines on your LAN. My situation is 
complicated by the fact that 2 of the machines run Windoze, and file 
sharing with them requires the LMhosts files to be populated with the 
mapping fron machine name to IP address. I've done a bit of desultory 
scratching around to see how to do it, but for the moment I've 
capitulated and allocated static IP addresses (which is manageable for 4 

I rather think the answer is somewhere between your a) and b) - it isn't 
stupidity on your part, but neither is it rocket science to do what we 
would both like to do...

Ian Park
17 Pyle Hill
RG14 7JJ
Tel: +44 (0)1635 821420
email: ian at chalmers-park.name

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