PLIP

I got PLIP working by adding a boot parameter specifying the IRQ to both my desktop PC and the notebook. I had constructed a cable for this purpose beforehand. Effective average throughput is up to 350 kbps. The /etc/init.d/network on both machines is provided in Appendix E.

Cable wiring details and other useful information may be found in the kernel source code in usr/src/linux/drivers/net/plip.c and also in /usr/src/linux/Documentation/net/PLIP.txt. Note that when using PLIP, the interactive performance of the machine suffers enormously. However, when sucking mp3s and the like from machine to machine, it's a hell of a lot better than floppies and much cheaper than a PCMCIA Ethernet card.

For further fun and excitement, you can set your desktop machine up as a router / firewall and effectively get direct Internet access through the PLIP connection. Since I want this document to stay fairly up-to-date, here is the procedure for the desktop machine, for a recent 2.3 kernel (works as of 2.3.31):

1. Turn on Network Packet Filtering under Network Options in the kernel source;
2. Compile and install the kernel. Reboot;
3. Download, compile and install the netfilter modules and tools - get everything you need from http://netfilter.kernelnotes.org. You'll need the latest version.
4. We will be using the IPChains compatibility module for now since it is the easiest one to set up. This module needs to be manually copied to the /lib/modules/2.3.xx/net directory. Run 'modprobe ipchains'.
5. some more info here