[lug] DHCP surrogate?

[Peter Hutnick]

> I am wondering something about DHCP, while figuring out the best ways to
>  add the cable modem network for 3+ computers to share (independently,
> and simultaneously). If 3 DHCP addresses are paid for, but the three
> machines behind the linux bridge turn off or on randomly, then in theory
>  the address issued by the DHCP can change between reboots. If the linux
>  bridge/firewall/filter (up 24/7) were to somehow be able to remember
> the  MAC address of machines which previously were attached, and provide
> a  fake "stub" MAC address for machines that shut down, then the IP
> address  could be held all of the time. Does anyone know if it is
> possible for a  bridge or gateway to act as a holding stub for DHCP
> addresses when the  machines that really used the address shut down? It
> isn't necessary, but  could be useful.

Most DHCP servers have some degree of MAC affinity.  You'll probably find
that it just works.

Beyond that, your math seems to be off, 3 IPs, 3 PCs and a router . . .

As for trying to hold onto an IP with the router you /could/ just put the
machine that needs the "stable" IP on a private IP, allow the router to
take one of the DHCP addresses and just forward the ports you need.

-Peter