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About - What is Shaolinux Temple?

News - Temple Updates, News Items, and Miscellaneous Rants

Techniques

Linux Router - Building a Cable/DSL Router Out of Old Junk

GRUB Intro - Introduction to the GNU Grand Unified Bootloader

OpenBSD Mac - Installing OpenBSD on a Vintage Macintosh

Linux+ Exam - A Few Notes On CompTIA's Basic Linux Certification

AT Keyboard to PS/2 - A Silly Hack to Convert an AT-style Keyboard to PS/2

DVD Ripping with Linux - Storing DVD Video Data with DivX, XviD, and Other Cool Codecs

HPing Demo - Exploring the HPing utility

Features

CHAOS-Chattahoochee Area Open Sourcers - the 706 Area's BSD and Linux User Group

Temple Evangelism - Sharing the Shaolinux Way of Life

Geek Scrapbook - Various Bits of Technical Info That I Keep in Case I Forget


Linux Router: The Implementation




Obviously, I was lucky enough to have the old computer available to me for use in this project. I you happen to be starting from scratch, I'd recommend scavenging at your local computer junkstore, or even better deals can sometimes be had at http://www.retrobox.com (those guys rock!) A 486 is probably beefy enough to do this, and you don't need anything besides a floppy drive and a stick of RAM, so if you're paying for anything else you're wasting your money. I'm talking $30, max, that's if you absolutely can't find anything for FREE, check garage sales or schools for people throwing out hardware (people think it's worthless when they can't run Windows on it!) If you're buying from Retrobox, try and get one with the NIC's already in it, sometimes you'll get lucky with them. Shipping will kill you though.

Make sure the system boots normally, and detects the RAM and floppy drive.

If you intend this box to act as a router for more than one end-user, you'll also need an ethernet hub. I bought mine (D-Link hubby 5), retail, for $38. I probably paid too much, but I was in a hurry. Better deals may be had on http://www.pricewatch.com, or again, check your junk stores and similar places.

Two ethernet cards will be needed for the new box. One is for dealing with the WAN (your broadband link to the Internet) and the other is for your LAN (your internal network at the house.) Do your homework before buying them; try and identify chipsets that have drivers available for Linux. Reference the HOWTO at http://www.linuxdoc.org/HOWTO/Ethernet-HOWTO.html for general information, and a lead on what chipsets are supported. PCI cards will give you a better shot at being supported, but make sure the computer in question supports PCI. ISA cards may prove to be harder to find. Of course, you'll also need a card in the end-machine on your internal network to receive the connection.

Obtain proper ethernet cabling for your purposes. For those who wish their box to act as a router to multiple machines, you'll need at least three sections of (straight-through) cable, and an additional section for each machine (beyond the first) that you wish to support on the network. To be more specific, you'll need one section from your DSL (or cable) modem to the router (assuming the modem in question uses ethernet!), one from the router to the hub, and one from the hub to the end-workstation.

If your setup isn't intended for more than just a single machine (i.e., a firewall and nothing else) than you may get away with one straight-through section (DSL/Cable modem to router) and one "crossover" section (router to end-workstation.) A crossover cable is needed when two NIC's are speaking directly to each other, as in this case. Make sure you buy the right one(s). Usually, a teeny green LED will light up on the NIC when the cabling's right.

Now, you'll need the disk image. This can get a tad bit invloved, depending on your particular needs. My "special need" was this: my DSL connection uses something called Point-to-Point Protocal over Ethernet (PPPoe) to establish a connection. There's a great package called Roaring Penguin PPPoE for Linux that does this job just fine, but I needed a very compact Linux distro that either included this package, or allowed enough room for me to put it on myself.

After a few days of poking around the Net, I discovered a variation of the original Linux Router Project (LRP) called EigerStein, that someone had kindly configured for use with RP-PPPoE. Seeing as how I've lost the original source of the particular image I'm now using, I'll mirror it here at http://www.shaolinuxtemple.org/eigerstein-pppoe.img in the meantime.

This image is designed for a 1680K floppy. Most websites offering the LRP/ EigerStein images (http://lrp.steinkuehler.net/DiskImages/Eiger/EigerStein.htm) offer MS-DOS executables to automatically create these diskettes for you. If using MS-Anything makes you sick to your stomach, do it in Linux...

bashprompt# fdformat /dev/fd0u1680

When the disk is done formatting, write the image to it...

bashprompt# dd if=eigerstein-pppoe.img of=/dev/fd0u1680

Assuming everything went okay, you now have a bootable Linux on a floppy disk. Pop it in your router's floppy drive and power on. A minimal kernel should boot and automatically decompress the filesystem into a RAM disk.

The default installation makes a couple wild guesses at your NIC's chipsets, which will likely turn out to be wrong. In my case, I needed the pcnet32.o module. I used one compiled from kernel 2.2.16-1, since this is the kernel my disk image is using. To transfer this module to the disk, I mounted it under my workstation's filesystem...

bashprompt# mount /dev/fd0u1680 /mnt/floppy

...and copied the module to the floppy...

bashprompt# cp 2.2.16-1/modules/net/pcnet32.o /mnt/floppy

bashprompt# umount /mnt/floppy

Now, from the *router* filesystem, mount the floppy in question and copy the module to the RAM disk filesystem...

routerprompt# mount.boot /mnt

routerprompt# cp /mnt/pcnet32.o /lib/modules

routerprompt# rm /mnt/pcnet32.o

routerprompt# umount /mnt

And add a line to /etc/modules reflecting this particular modules. In my case, it was as easy as...

routerprompt# echo "pcnet32" >> /etc/modules

Now, you'll need reflect these changes to the actual compressed filesystem stored on the floppy. Enter "lrcfg" to access the EigerStein menu, and choose option "b" to backup the RAM disk to floppy. Remember, you'll need to do this anytime you modify the installation, so your changes will survive a reboot.

Once backed up, reboot and see if your NIC's were detected. If so, awesome. If not, I can only direct you to linuxdoc.org for further info. Sorry.

Assuming the cards worked, check your cabling one more time. WAN goes to eth0, and LAN goes to eth1, if you can figure out which one is which yet. At this point, if everything has worked thus far, and you use it, configure the DSL PPPoE setup by typing "adsl-setup". This menu will direct you through the configuration, and write the changes to (RAM) disk. Don't forget, once the config is done properly, back it up, or you'll lose it on reboot!!!

As a side note, the default firewall configuration in the adsl-setup options caused my router to drop all my packets to the WAN, so I had to manually configure a firewall later.

With the WAN setup done, LAN should be easy. EigerStein has a DHCP server already configured for handing out IP's on the 192.168.1.* private network, so just run a DHCP client on the workstation(s) you are connnecting. EigerStein is also configured for IP masquerading, without additional setup from you.

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