dhclient: lease renewal woes

[Mr Dash Four]

>>> Otherwise do you have a system that you could run your own dhcp 
>>> server on?
>> That won't help me much because, as I stated above, this is my exit 
>> point to the "world" and without this I won't be connected at all.
> Actually, you can make that work. You can take the parameters that the 
> modem gives out:
> - default router
> - DNS
> - network mask
>
> and provide those from another DHCP server after disabling the DHCP 
> server in the CM.
How? I know all of the parameters you listed above as they've never 
changed (and I am with this provider close to 10 years now), but I also 
need my own (i.e. my firewall's) IP address when I get it from my 
provider (and this IP address changes from time to time, so it is not a 
constant), so how am I going to pull that one off?

> Which CM is it, by the way?
Motorola surfboard.