[Gllug] ADSL (and DHCP) woes

[Ian Northeast]

chris.wareham at btopenworld.com wrote:
> 
> Last weekend I trod on my BT supplied modem (the fish shaped thing),  
> completely buggering it up in the process. Not a problem, as I'd been looking 
> for an excuse to relace it with a non-USB one for a while.
> 
> So I've now got a D-Link DSL-300G . Quite neat in principle, just plug it into > an ADSL filter and connect an ethernet cable from it to the computer. 
> Configuration is via a couple of web pages, no proprietary or Windows only 
> guff.
> 
> But ... it uses DHCP to assign an address, netmask, gateway, etc. to the 
> connected computer. Works flawlessly on the Windows XP machine my girlfriend 
> owns, but I can't get it going under NetBSD. I've created a dhclient.conf file > as described in the manual pages, and it gets the address from the modem. But 
> my networking setup looks entirely different under NetBSD than it does on 
> Windows.
> 
> Under Windows, the computer has the address assigned by BT Openworld, which 
> seems strange. I expected the computer to have a 192.168.0.* address, and to 
> use 192.168.0.1 (the modem's address) for both gateway and name server. Or the > DHCP stuff would setup the correct nameservers.
> 
> So has anyone used this ethernet modem with Linux? I'm at a loss as to what to > do. I don't want to dual home a Windows machine and stick my network behind 
> that 

Chris, I have never used this modem or indeed ADSL, but if it is working
in Windows it should not be hard in NetBSD. It should just be a matter
of getting the DHCP client configured. I assume that NetBSD is using the
same ISC dhclient program as the OpenBSD system I use with my cable
modem. I would expect the requirements to be similar.

You say that your networking setup looks completely different in NetBSD.
Exactly how does it differ? And what does your dhclient.conf actually
look like? Mine is very simple i.e.:

initial-interval 1;
send host-name "firewall";
request subnet-mask, broadcast-address, routers; 

and I think sending my hostname is irrelevant. With this setup I am not
requesting nameservers, as I run my own. If you want DNS information
from the DHCP server you should add "domain-name-servers" and possibly
"domain-name" to the request list.

What messages does dhclient issue? On my system they are in
/var/log/daemon but this may be different in NetBSD; of course you can
always explicitly request a lease with "dhclient <interface>" to get the
messages directly. Mine looks like (on renewel; on the initial request
there is a broadcast first):

Dec 30 17:04:36 firewall dhclient: DHCPREQUEST on ep0 to 10.0.116.71
port 67
Dec 30 17:04:36 firewall dhclient: DHCPACK from 10.0.116.71
Dec 30 17:04:37 firewall dhclient: bound to 80.0.70.57 -- renewal in
302400 seco
nds.

So in my case the DHCP server itself has a private address but is giving
me my real ISP assigned one, which seems to accord with your situation.

Regards, Ian

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