CentOS4 rt2500 Howto
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
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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
II. PREPPING FOR THE BUILD
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.
III. BUILDING THE MODULE
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:
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
This will build the rt2500.o module and put it in place.
IV. CONFIGURING YOUR CARD
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
desc: "RaLink Ralink RT2500 802.11 Cardbus Reference Card"
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=192.168.1.123 # replace with proper IP address
GATEWAY=192.168.1.1 # 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
V. BRINGING UP YOUR WIRELESS CARD
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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