m0n0wall Forum - Is there anyway to control the transmit power on the PCI

You can set this manually using one of the undocumented monowall options.

Execute a command
http://<m0n0wall-ip>/exec.php

where <m0n0wall-ip> is the IP address you use to connect to the Web management interface. This brings up a command window that allows you to run any shell command.

In the command window type the following command to see all configured network devices:
ifconfig -a
This above command lists all configured network devices.

If you have a single atheros wireless card installed, then you should see an entry for the ath0 device. The txpowmax value listed for the ath0 device lists the current default transmit power setting.

Note that the units of power are in 0.5 dBm units. So value of 40 = 20 dBm (100mW)

You can change the transmit power setting by executing the following command:
ifconfig ath0 txpower <power>
where <power> is the setting you want for transmit power.
This assumes that ath0 is your wireless device.

Example:
ifconfig ath0 txpower 40

Based on the FreeBSD docs for ifconfig, out of range values are truncated. Only a few discrete power settings are available. The driver will use the setting closest to the specified value. Not all adapters support changing transmit power.

These commands worked fine for with a Compex WLM54G miniPCI wireless card on monowall 1.3. I could see a noticeable drop in power using a client when I changed the setting from 40 (100mW) to 10 (25mW). You would have to look at the ath0 device driver sources in FreeBSD 6.4 (monowall 1.3) to determine what discrete power settings are available. I'll get around to this eventually.

Of course, if the monowall system is rebooted, then this option is lost.

It should be possible to use one of the monowall hidden config options to manually set this option in your config.xml
http://doc.m0n0.ch/handbook/faq-hiddenopts.html

I have not tested this yet, but the system/shellcmd should allow you to have monowall run this same command after booting:
ifconfig ath0 txpower 40

The following Wiki article gives an example of how to use the <shellcmd>:
http://wiki.m0n0.ch/wikka.php?wakka=HostTracking

You should be careful with your edits and test the config.xml on a local monowall if possible. After you have hand edited the config.xml file, you need to upload it to monowall and reboot the system.

-msbaker