Robert Nichols wrote:
If your other machines are set up to use the DSL router as the default route, of course that's where the return packets will go. You have two choices: 1. (Preferable) Set up the default route on your other machines so that they use the firewall machine as their gateway to the outside world.
Which is what's happening now. DNSMasq (lightweight DHCP/DNS server) allocates IP addresses based on /etc/ethers and /etc/hosts, and tells those machines to use 10.0.0.1 as the gateway. 10.0.0.1 (the firewall server) forwards those onto their eventual destination, and handles masquerading in the opposite direction, so that one or more LAN-based machines can access the Internet using only one public IP address.
2. SNAT the forwarded packets so that they appear to come from the firewall machine. This really screws up logging on your other machines (all traffic will appear to originate on the firewall machine), so you probably don't want to do it that way.
Based on
If that's Oskar Andreasson's tutorial you've got, you'll find you
Yep.
really don't need to read through the whole thing. The section on the DNAT target is what you need right now.
Well, I've read the chapter on TCP/IP, now I'm just skimming through the stuff on DNAT and Masquerading. Problem with DNAT is that it seems to be more of a port-forwarding system rather than allowing more than one machine to access the Internet from one public IP.
I think I'll spend tonight playing around with firewall rules and routing tables. No doubt I'll take some flak from the rest of the family in the process ("why can't you just use the old modem?" and stuff like that)
I was going to use "Arno's IPTables Firewall" to do this, but it doesn't seem to support single-NIC NAT routing. Guess I'll have to write my own firewall script.. in at the deep end, as always :)
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