DHCP conflict on cable modem?

I want to set up a LAN using DHCP to assign IP addresses to local hosts.  My cable modem service also uses DHCP.  It appears I must configure my DHCP server to see the ISP's network but mark it "not authoritative." Is this correct? Also, I understand there is still a chance that the ISP's DHCP server will NAK my local hosts when they seek IP addresses from my DHCP server.  Is it sufficient for me to limit my server's address range to 192.168.0. or similar?  I am using 2 nic's and plan to use IP masquerading to give the local hosts access to the internet.
RonJDAsked:
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RonJDAuthor Commented:
Edited text of question.
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j2Commented:
1. use two nics

2. use 192.168.x.y on the internal NIC (lets call eth0 external, and eth1 internal)

3. Set eth0 to use DHCP

4. setup dhcpcd, and create the config file. (if you want mine, just ask)

5. launch dhcpcd with the line "dhcpcd eth1" this will make your server only listen on the internal network.

this works without a hitch for me. Feel free to ask furter.
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RonJDAuthor Commented:
Your response sounds very encouraging except for one point on which I am confused.  You mention configuring the DHCP client daemon (dhcpcd) for eth1.  Did you actually mean the server daemon, or must I reconfigure all of the DHCP clients (including the MS Windows 9x clients on my local net) in some special way?  I would rather not do that, since I would like to have the option of shutting down the Linux box from time to time and connecting the Win9x DHCP clients directly to the cable ISP.
      I want my local DHCP server to give the Win9x machines addresses in some 168.192.x.y range when that server is in service.  I understand that your scheme does this.  But I also want (with some replugging on the hub) for the Windows machines to be able to request IP addresses directly from the cable ISP, when the Linux box is shut down.  Is your scheme capable of this?
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j2Commented:
No. And unless your ISP actually GIVES you multiple IP's that wont happen. The only thing you can do is just plug one machine into the cable modem, thats all you can do. And you will probably just get ONE ip from your ISP.

My scheme requires a local dhcp server, and since my cable isp only assigns ONE ip per cable modem, i would have to plug one puter straight to the modem if my linux went down.. but it has a 178 day uptime now (ever since it was installed) so that isnt really a factor.
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RonJDAuthor Commented:
Thanks for putting me onto something useful.  I was unaware that I could specify the NIC to which the DHCP server would listen.  Our ISP does indeed provide multiple IP addresses, as we have verified many times when running under Windows.  I will try to use IP masquerading to allow the Windows machine to connect to the internet through the Linux gateway.
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j2Commented:
i noticed that i wrote "dhcpcd" when it in fact should be dhcpd (dhcpcd is a client daemon) but you seem to have worked that out. :)
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