How to I network two PCs together with Ethernet

[Harry Kuhman]

Harry: I have a question about the private unroutable address. Exactly what in the 192.168.1.2 numbers guarantees it doesn't match some IP address somewhere on the net if I have a dialup modem online with the ethernet between the two PCs on?

The Internet TCP/IP spec defines some unroutable IP address ranges for just this purpose (sorry, I can't give you the exact RFC #). Off the top of my head, 10.xxx.xxx.xxx and 192.168.xxx.xxx are defined to be unroutable, there may be others but 192.168.xxx.xxx is the most common used for home networks. I don't know what logic, if any, was used to select these ranges.

Other people may certainly be using those numbers as well, but since they will not route on the 'net they can't see yours and you can't see them, so there is no conflict. That you are connecting via dial-up brings up another issue; that connection will end up with it's own IP address and your system will figure out what to send to the local lan and what to send to the dial-up, but as long as you use these addresses things will be safe even when you are directly connected to the Internet through the same NIC.

Another detail I didn't mention Knoppix seems to think the laptop has two ethernet ports. I am using a PCMCIA card and assume that it's eth1.

Actually I would expect it to be eth0, but I'm not clear why Knoppix thinks you have multiple NICs unless you have a motherboard with a built-in NIC. You don't , do you? (many recent laptops do). And you don't have built-in wireless in that laptop, do you? Try either and/or both of the connections Knoppix thinks it sees.

I suspect something might be wrong because if I run netcardconfig on the client tower PC, with the DHCP, DHCP doesn't work.

I'm not clear here where you think the DHCP server is that would supply an IP address when you do this, unless you already have DHCP services running on the laptop. If you had a home DSL/Cable router it would server as a DHCP server and assign you a DHCP address (even if it was not connected to the Internet, and, in fact, even if it never connected to the Internet (although the DHCP setup might make your computer keep trying to get to the Internet through that router, even if you did make a dial-up connection, unless you reset a few things)).

I'm not an expert on hard disk install (nor on many other things), so I'm going to back out and hope others can give you more help than I, but at least I hope I answered some of your first questions.