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CentOS4 rt2500 Howto

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RT2500 CentOS 4 HOWTO

Copyright (c) 2005 Aaron P. Howard

Permission is granted to copy, distribute and/or modify this document

under the terms of the GNU Free Documentation License, Version 1.2

or any later version published by the Free Software Foundation;

with no Invariant Sections, no Front-Cover Texts, and no Back-Cover

Texts. A copy of the license is included in the section entitled "GNU

Free Documentation License".


This is a HOWTO document for getting the an 802.11g card based on the

RT2500 chipset to work under CentOS 4, which is a Red Hat Enterprise

Linux 4 rebuild project. These same instructions should work with

RHEL4 but Your Mileage May Vary. I am using a Linksys WMP54G PCI



Before you begin this process, make sure you have proper build chain

installed. These are usually there in a standard install, but I

stripped all the tools necessary for a build chain out of my system

and had to re-install them. Unless you removed these, they are

probably already present on your system. I re-installed them using

RPMs off of the CentOS CDs. Here's what I had to re-install in order

for this to work:

From CentOS 4 CD1, under CentOS/RPMS:







From CentOS 4 CD2, under CentOS/RPMS:







Now, some of these are probably not necessary (specifically, m4, perl,

perl-Filter, and autoconf) if you are only compiling the module (as I

did). But they are there just in case and may be necessary if you

build the utility (which I did not and this HOWTO doesn't cover).

Again, if you do a standard install and don't purposefully strip out

the build chain, many of these are probably already present (with the

possible exception of kernel-devel, glibc-devel, glibc-headers, and

glibc-kernheaders). Just make sure those are available.


First, download the source for the RT2500 driver module via sourceforge.

I downloaded mine from the voxel mirror using the following wget command:


You can get it from whatever mirror you like. Just make sure you're

getting the rt2500 driver, not the rt2400 driver.

Second, untar the thing. I tend to place source tarballs in /usr/src

and then untar them like this:

tar xzvf rt2500-1.1.0-b2.tar.gz

This will create a new folder from the current directory called

"rt2500-1.1.0" (without the quotes) under which is another folder

called "Module" (again, without the quotes). That's where you want

to be so cd there:

cd rt2500-1.1.0/Module

Now, in order for this to compile, you have to have the kernel headers

and source installed and you have to create a link to the kernel source

under /lib/modules/2.6.9-5.0.3.EL called "build" (without the quotes)

that points to "/usr/src/kernels/2.6.9-5.0.3.EL-i686" (also without

quotes). To create this link, type the following:

ln -s /usr/src/kernes/2.6.9-5.0.3.EL-i686 /lib/modules/2.6.9-5.0.3.EL/build

Now, from the /usr/src/rt2500-1.1.0/Module directory, issue these



make install

This will build the rt2500.o module and put it in place.


CentOS recognizes the wireless NIC before you have this driver in

place, but it doesn't know what driver to use. It will already

assign the NIC an interface name (like eth0 or eth1). In my system,

this was eth1 (because eth0 was taken by an on-board 3c905 controller)

so that's what I'll use for my configuration info. To determine

what yours is, run lspci as root to see that the card is detected.

My card is and lspci's output looks like this:

00:0e.0 Network controller: RaLink Ralink RT2500 802.11 Cardbus Reference Card (rev 01)

(the rest of the output of lspci is not displayed here)

Next, check the file /etc/sysconfig/hwconf for a device that looks

similar to this one. The contents of this file on my system shows

these lines:


class: NETWORK

bus: PCI

detached: 0

device: eth1

driver: unknown

desc: "RaLink Ralink RT2500 802.11 Cardbus Reference Card"

vendorId: 1814

deviceId: 0201

subVendorId: 1737

subDeviceId: 0032

pciType: 1

pcidom: 0

pcibus: 0

pcidev: e

pcifn: 0


Here you see the line "device: eth1" which tells me that's what I

want to set my wireless device up as. I imagine you could do this

differently, but this is what worked for me.

So, given that the system sees the card, and thinks it's eth1, but

doesn't know what device driver to use, I need to tell it which one

to use. When you issue the "make install" command, a line will be

added to /etc/modules.conf that reads "alias ra0 rt2500" but that

is not where you want the alias line to go. For CentOS, it needs

to be in the /etc/modprobe.conf file. And, it shouldn't be ra0,

it should be eth1 (or whatever device you have it as on your system).

To adjust this, type the following:

cat >> /etc/modprobe.conf << EOF

alias eth1 rt2500


and then, rename or remove the /etc/modules.conf file (I renamed it).

The last step to configuring your device is to create an ifcfg-eth1

file under /etc/sysconfig/network-scripts. Type the following to

create this file:

cat > /etc/sysconfig/network-scripts/ifcfg-eth1 << EOF



HWADDR=00:00:00:00:00:00 # replace this with your MAC address




IPADDR= # replace with proper IP address

GATEWAY= # replace with proper gateway address






ESSID=any # replace with proper ESS ID

CHANNEL=1 # set to proper channel

MODE=Managed # don't know what happens if set Adhoc

RATE=54Mb/s # could choose other rates



After you've built the module and created the ifcfg files to match

your needs, you can control the interface using standard CentOS

ifup/ifdown commands. By entering the ONBOOT=yes line in the ifcfg

file, you are setting your system to automatically enable this

interface when it boots up. You can now type "ifup eth1" and

"ifdown eth1" to start and stop the wireless interface and it will

be automatically up whenever you reboot.


I only experienced two problems in getting this up and running:

1) the initial "make" of the module failed because I hadn't created

the "build" symlink.


2) The first time I issued my "ifup eth1" command, it would not

communicate with my access point. Apparently, this was because I

had the "CHANNEL=1" line above and my AP was running on channel 6.

When I changed that line to "CHANNEL=6" it worked just fine.

If you have any other problems, you can always try Google.

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This page has been accessed 26,948 times. This page was last modified 23:26, 30 April 2005 by Mark Wallis. Content is available under GNU Free Documentation License 1.2.

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