dhclient oddness?

[Mark Cullen]

Lowell Gilbert wrote:
> Mark Cullen <mark.cullen at dsl.pipex.com> writes:
> 
> 
>>Right, I have this weird annoying issue with my modem which I have
>>finally got around to looking in to. Basically, it's all good and
>>works fine (obviously, otherwise I wouldn't be here!), except when I
>>reboot the internet computer the IP will change, the connection
>>DOESN'T drop, but the IP does change. I have just now narrowed this
>>down to some sort of problem with dhcp I think.
>>
>>The modem has a dhcpd server built in, which sends out the internet IP
>>address to the computers network card. It seems, whenever the dhcp
>>client, dhclient in this case, gets restarted it'll get the old ip
>>address (the first chunk of the quote below, before the <freeze>),
>>natd will update itself, but then the connection will just stall until
>>dhclient does the next DHCPREQUEST thing (47 seconds in this case?)
>>.. then the modem sends back a DHCPNAK and I get a different IP
>>address. Any ideas why this might be happening?
> 
> 
> Your "modem" is clearly the source of the problem, and it seems
> unlikely that anything on the FreeBSD side could help, aside from
> maybe forcing a lease free before starting dhclient on startup.
> 
> I'd try looking at the configuration for that "modem" device, or
> possibly for a firmware upgrade for it.
> 

Hi,

Could you explain what's going on to me? I mean, in simplified terms, 
what exactly is causing the modem to get a new IP address when dhclient 
restarts?  I have contacted them about the issue and they seem to think 
it's an O/S problem (well, it's *obviously* not an issue with their 
modem now, is it? :-P).

How would I go about forcing a 'lease free'? Delete dhclient.leases, or 
some option somewhere that I missed?

As for configuration, there's no config for the DHCP server and there's 
never been a firmware upgrade for it (this is the only issue I have EVER 
had with it and I expect most users don't notice it).

Thanks