by December 31, 1998 0 comments

The Linux Router Project (LRP)–”Embedding the
Bird for the Sake of All Humanity”–is a tiny Linux distribution that
fits, and runs off a single floppy drive. It’s designed to allow you
to convert almost any old hardware lying around–even a 386–into a
network router, gateway, firewall, or almost anything else you can
think of. Of course, you can use it like any other router or gateway
on your network, irrespective of what network operating system you
are using.


Installing the basic router is
a piece of cake once you figure out how. The first thing you
discover is that there isn’t as much documentation. More
importantly, there are no “step-by-step” setup instructions to get
you going. There is an “Idiot” setup, which works, but you will
probably need to customize it further to your needs. Additionally,
several important steps in the setup, such as adding functionality
(through additional packages), aren’t documented anywhere but on the
mailing list.


Setting up


Creating an LRP disk doesn’t
require you to have a Linux system available. You can create it
entirely from within DOS or Windows. You will additionally need a
“zip” and “tar” utility to extract the files. WinZip (on the CD-ROM)
will do both.


If you choose to use the Idiot
install, then it is simply a matter of using the supplied
“rawrite2.exe” to copy the disk image to a floppy for an instant
start. But before we start, here’s a warning: Be sure to have brand
new, freshly formatted floppies before you begin. Save yourself
hours of frustration by not trying to use old dusty
floppies.


Find out the exact model, name
and IRQ and I/O settings for your network adapter(s). If you are
using PCI plug-n-play cards, you are not likely to have a problem.
Even so, it’s better to have the details written down somewhere. In
the case of old ISA adapters, you will have to configure them
beforehand to eliminate any potential conflicts. Usually these cards
have a DOS utility to save the configuration to EEPROM.


Installing the Idiot way


Copy the file
CDROM:\cdrom\Linux \router\software\utils\rawrite2.exe to a
directory in your path, such as C:\win dows\command.


Cd to the directory CDROM:\
cdrom\Linux\router\software, and type in:


rawrite2 idiot.image-2.9.3-
1.44MB
a:


If you’re doing this in DOS mode, you will
have to substitute the short name “idiot~1.44m”.


Once the file has finished
copying, you have a fully usable LRP floppy, though at this point,
without networking support.


Now use WinZip (if you’re in
Windows) to extract the appropriate modules for your network
adapter(s) from the archive CDROM:\cdrom\Linux\
router\software\kernel\kernel-36pre2-1.tar.gz and copy those to the
LRP floppy. Overwrite the existing “modules.lrp” file on the floppy
with the file from CDROM:\cdrom\Linux\router\software
\base


Now you have your disk ready.







What’s on the
floppy?


The LRP is a Linux
distribution with its own package format. It ships with:
bare-bones 2.0.36 kernel, full set of compiled modules, and
packages for ppp, snmp, ssh, WAN router, gated, and several
others. You can additionally add almost any other components
you wish to the setup, provided you can accommodate them on
the boot disk you are using.


The LRP has three basic
packages–the “root” package which contains all the binaries in
/usr/ and /bin, and any configuration files or scripts needed
before other packages are loaded. The “etc” package which
contains all the config files in /etc/. The “modules” package,
which by default, is empty (you have to choose your own
modules), and the kernel image itself.


The boot device (the
floppy) itself is not usually used after booting. A RAM-disk
(/dev/ram0) is created at boot time, on which a minix file
system is created, and a raw system image is copied by the
boot loader. After this, the additional packages are loaded
and uncompressed, and the router then runs entirely out of RAM
(Fast!). However, since all configuration changes you make to
the system exist only in RAM, you have to back up the root
image to the floppy to save it for the next boot.


Hardware requirements are modest,
starting with a 386SX with 8 MB RAM. A more practical solution
calls for a 486DX2, or old Pentium and 16 MB RAM. You can even
use a Iomega Zip disk or Imation LS-120 floppy drive, which
can turn your router into a full fledged Linux distribution,
albeit with the increased cost of hardware.


The “roll-your-own” way


If you want to choose your own
components, here’s how to go about doing it.


Extract the file “syslinux.com”
from the archive CDROM:\cdrom\Linux\
router\software\utils\syslinux-1.40.zip., and copy it to a directory
in your path. Put a DOS formatted floppy in the drive, and ‘syslinux
-s a:’


Now extract the kernel archive
CDROM:\cdrom\Linux\router\software\
kernel\kernel-36pre2-1.tar.gz


There are two stock kernels
available, one with FPU emulation (if you have a 386/486 SX), copy
the kernel of your choice to the floppy drive as “Linux”. Now CD to
the base subdirectory, and copy the files “etc.lrp”, “root.lrp”, and
“modules.lrp” to the floppy disk. If you want to enable logging,
copy the file “log.lrp” as well. From the boot directory, copy the
files “syslinux.dpy” and “syslinux.cfg”.


Your disk is ready. Before we
progress, it’s a good time to read the accompanying HTML docs on the
CD.


Configuring the router


Now that you have the floppy
ready, it’s time to configure your router.


Take your floppy over to the
machine you want to use as your router, (which we assume doesn’t
have niceties such as a CD-ROM or hard drive. You will need a
keyboard and monitor initially), and boot it. To start with,
networking will not be initialized–you still have to configure it.
Login as “root” when prompted, and you will be presented with a
simple menu interface to configure the system, networking, and
modules.


Select “Networking
configuration” from the menu. You can edit all the system networking
files from here.


The first item–IPs, routes,
ipfwadm–allows you to specify how many network interfaces you have
and their IP addresses. You also specify ipfwadm and IP masquerading
rules.
(See the May ’98 PCQ article on setting up Linux as an
Internet gateway, www.pcquest.com/may98/gateway. html, for details).
By default the script allows up to four network interfaces, but its
simple to add more if necessary. Simply uncomment the [IF0] line to
enable the first interface, [IF1] for the second, etc. You will also
have to set the IP and Broadcast addresses.


Further down the file you will
see entries prompting you to add static routes, gateways, etc. If
you’re lost at this point, its strongly suggested that you read the
Linux Net-HOWTO’s (http://metalab.unc.edu/LDP/) before you attempt
to go any further.


Next edit the file /etc/hosts
to give yourself a machine name and domain name. We named our router
“shoebox”, because that’s what it would fit in. Similarly, add
entries for which networks your machine will belong to in the
“networks” file. Edit “hostname” to give your machine a hostname,
“resolv.conf” to add nameservers for your domain and “gateways” to
specify gateways for routed (if necessary). Once you have set up the
networking options, press “q” to return to the main menu, and select
“System”. Here, you can edit the securetty, syslog, inetd.conf, and
inittab configuration files if you want. All of them worked fine
with default values in our case.


Finally, select the “modules”
option from the main menu, and uncomment the entry corresponding to
the ethernet drivers for your network card(s). When editing the
modules file, it is important to list the modules in the order in
which they are to be loaded. If module “B” is dependent on module
“A”, then module “A” must come before module “B” in the list. If you
need to specify parameters to the modules, you may do so. For
example, “ne io=0x330, 0x350”


When you are done, press “q”
repeatedly to exit to the command prompt. Immediately secure “root”
with a password.


Create a “/mnt” directory in
the root, and mount the floppy drive
mount -t msdos /dev/fd0
/mnt
Copy the modules (*.o) to the directory /lib/modules. Then
delete the modules from the root of the floppy drive.


Type “insmod
/lib/modules/module name.o <paramters>” to load the modules.
If all goes well, you will see a message notifying you that the
drivers have been loaded. If not, you may have to specify additional
parameters for your module.


At this stage, you should back
up your root to the floppy. Unmount the floppy with “umount /mnt”.
Type “lrcfg” to return to the menu, and press “b” to begin writing
your configuration to the floppy. Once it is finished, exit the
menu, and reboot the system with “reboot”.


When the system boots the next
time, you should be prompted with a login prompt “shoebox login:”
(or whatever you call it). Type “ifconfig” to see a list of active
network interfaces. You can then try pinging other machine and from
other machines. Since the routing tables are created by default, you
should be able to ping across subnets. If not, check your routing
tables with the command “netstat —nr”.


Setting up the gateway


To set up the machine as a PPP
gateway (a Web connection sharing device) to the Internet using ISDN
or modem, you need to add the “ppp.lrp” package to the floppy from
the “packages” subdirectory on the CD-ROM. Then edit the file
“syslinux.cfg” and add the entry “ppp” at the end. The end of the
file will now look like this:


append=load_ramdisk=1 initrd=root.lrp
initrd_archive=minix ramdisk_size=4096 root=/dev/ram0
boot=/dev/fd0,msdos LRP=etc,log,modules, ppp


If you have not set up ppp on a
Linux system before, read the article in the May issue. The
ppp configuration files such as /etc/ppp/options, can be edited from
the menu.


Now you will have to include
the modules for header compression ‘slhc.o’, ppp ‘ppp.o’, and serial
interfaces “serial.o”. Again, these files will need to be copied
from the kernel archive in to the directory /lib/modules. Run lrcfg
to edit the modules file and add entries for the three modules in
the order serial.o, slhc.o, ppp.o. Now manually install the modules
using insmod.


Back up your root image, and
connect to the Net using:


pppd connect ‘chat -v “” ATDT3334000 CONNECT
“” sername USERNAME assword PASSWORD ‘ /dev/ttySX 115200 debug
crtscts defaultroute


If you have trouble connecting,
you can monitor the progress of the call from the /var/log/messages
file (provided you have enabled logging). A stripped version of
minicom is available on the CD-ROM as well, if you wish to use that
to establish your connections.


You can easily customize the
router for your needs, such as using a high capacity boot disk (a
100 MB Zip disk), adding memory to increase the size of the default
ram disk, and adding any and as many packages as you can fit in. You
will find several add-ons and packages on this month’s CD-ROM. The
router makes an ideal replacement for hardware such as PowerTel
Boca’s WebRamp, especially when used with an ISDN connection. The
router and gateway that you just got going will cost about Rs 4,000
even if you were to buy it.


Nikhil
Datta

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