This paper describes the evaluation and implementation of a router/firewall using Coyote Linux for a Time-Warner Road Runner cable modem.
Adding the Roadrunner
cable modem required a change in the network hardware configuration. Central
Florida Roadrunner provided a 10BaseT modem. To connect all three nodes,
a hub was needed. Hubs are not intelligent and must be set to the lowest
common speed. Thus the internal transfer rate degraded by an order
of magnitude because of the cable modem. The hub was replaced
with a 10/100BT switch, but the system was still lacking security.
Coyote Linux boots a lean, mean version of Linux (kernel 2.2.14) from a 3.5" diskette. It requires a minimum of a 486 computer, 12 MB of memory, two Ethernet cards, and a floppy disk drive.
After printing Vortech web pages and reviewing the last 50 messages
of their very active Phorum message board, I was ready to configure my
first Coyote diskette. Because of my philosophy, "Use root only when necessary",
my first attempt failed. The commands fdformat or mkdosfs or perhaps the
permissions on /dev/fd were to blame. This is documented. So I logged in as
root and proceeded to build the coyote boot diskette without further problems.
To run the configuration, you should be logged in as root. This is needed
to write the boot sector to /dev/fd0.
You are asked a few question and then the diskette is created.
The questions are simple. They are driven by a Perl script. If you make
a typo, you may have to start over, as ^H is echoed to the screen. To run
the script, simply cd to the directory that you installed Coyote and enter
the command ./mkfloppy.sh.
1) What type of Internet configration is being used. Coyote
Version V.1.13 has one option 1) Standard Ethernet.
Future version may allow additional interfaces. Select 1.
2) Default IP, netmask, broadcast, network addresses are displayed. Question: Do you want to change these settings? Answer N.
3) Does your Internet connection get its IP address via DHCP? Answer Y.
4) Install the Roadrunner DEC protocol login software? Answer Y.
5) Do you want to install Coyote DHCP Server? Answer Y.
6) If you did not take the default in question 2, you will be asked to enter a starting and ending DHCP RANGE now. The default range is 192.168.0.128 to 192.168.0.254. You can enter this range unless the coyote IP is within this range.
7) Enter your DHCP host name. For Central Florida Roadrunner enter cfl.rr.com
8) Enter information for the Internet network card. In my case
the type is ne. (ne2000 and compatible)
The IO Address was 320. It expects hex numbers
here (don't use 0x.)
The interrupt was 10 (it expects decimal numbers
here. If its greater than 9, enter it).
9) Enter information for your local network card. This will be three parameters: type, ioport and irq. If you use the same type of card for both, less disk and memory space will be used because only one driver will be loaded. The program displays drivers dependencies. In this case 8390.o and ne.o were loaded.
10) Do you want to install the oidentd package. Select N.
11) Do you want to add the VPNd.? Select N.
A disk image is then created and you will be asked to insert a blank floppy and press enter to continue. A boot floppy is created. You are now ready to boot from the floppy.
Log is a root. There is no password. The lrcfg (linux router configurator)
is executed from the root login script.
Select the roadrunner configuration option. Enter your Roadrunner
username and password.
The menu gives you the ability to change other network parameters including ipchains configuration.
Because these changes only affect the ramdisk, use the backup command
to write the new configuration to the boot floppy.
Select option 6 show current status. Eth0 and eth1 should be up.
If not reboot. If you are not up, check the list below for possible
problems.
If an Ethernet line does not come up, verify that the IO address, and irq correct. Are there any other peripherals using those addresses?
Be sure to look at all of the screens of computers in your network. You may get a Windows message saying that a DHCP address has been requested. Select OK. If you don't close the dialog box, that network node may be hung awaiting mouse input. This occurred and caused a failure in sharing resources between internal computers.
Look at the lights on your Ethernet cards? Look at the lights on you hub or switch. Do they show communications activity? Does the cable modem show link and data indicators?
It has been documented by Vortech that some domain name servers cache information about your connection. Your connection may not work for the first 24 hours. On my first connection to the RoadRunner modem the router failed. I could ping the Internet from the coyote keyboard, but could not talk the local network. The Windows machines could not see the Internet. The next night, after reseaching the problem I was ready to change a lot of things Windows network parameters. I didn't have too! When Coyote booted, the Internet came up immediately.
In this case, both computers were loaded with configuration software provided by Roadrunner and both were used on the Roadrunner network prior to the installation of the Coyote router.
Vortech has a very active Phorum message board. If you have a problem check the board for similar symptoms.
This product will make your computer less suceptable to web attacks. If you do not have a Linux system to configure Coyote, consider purchasing the Windows version from Vortech or Prairie Wolf Software.
I highly recommend Coyote Linux to anyone who is using Road Runner.
A slide presentation of this paper was presented at the Melbourne Linux Users Group Meeting. That presentation can be viewed at http://www.graftacs.com/rrslides.