Supercharging Your Linksys Wireless Access Point

kwishot writes "Xam over at www.wi2600.org has documented a relatively simple way to 'turn up the juice' on your Linksys WAP11 Wireless Access Point." Caveats: the outlined method requires a Windows box, recent firmware, and (some) bravery, but no going inside the box or special hardware.

Re:Ignorant Legality Question

[clark625]

Generally, the FCC only cares that you are within specified guidelines. I believe (and someone will correct me if I'm wrong here) that the 2.4GHz spectrum is limited in radiated power to 1mW. You can play all kinds of tricks with that by using highly directional antennae, and thus concentrating your 1mW power into one small cone. Or, you can spread the love around and try and radiate the 1mW spherically from a point source (hard to do).

Most of the 802.11b devices don't radiate nearly as much as 1mW. This keeps them well below the FCC specs, and thus out of harm's way. Cranking your radiated power up to the full 1mW is perfectly fine. The caveat, of course, is that now you're sharing your traffic with much more of the planet.

Correction:

[clark625]

I goofed. The maximum radiated power is set at 1W. Not 1mW. Here's the FCC rules that apply, for those interested:

Part 15.247 covers intentional Radiators in the ISM bands that are the frequencies 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz. Besides covering the modulation schemes this part also covers the various power restrictions that the FCC has for devices like 802.11b. The critical section is 15.247(b)(1) through 15.247(b)(3)(i) quoted below:

"(b)The maximum peak output power of the intentional radiator shall not exceed the following:
(1) For frequency hopping systems operating in the 2400-2483.5 MHz or 5725-5850 MHz band and for all direct sequence systems: 1 watt.

(2) For frequency hopping systems operating in the 902-928 MHz band: 1 watt for systems employing at least 50 hopping channels; and, 0.25 watts for systems employing less than 50 hopping channels, but at least 25 hopping channels, as permitted under paragraph (a)(1)(i) of this section.

(3) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this section, if transmitting antennas of directional gain greater than 6 dBi are used the peak output power from the intentional radiator shall be reduced below the stated values in paragraphs (b)(1) or (b)(2) of this section, as appropriate, by the amount in dB that the directional gain of the antenna exceeds 6 dBi.

(i) Systems operating in the 2400-2483.5 MHz band that are used exclusively for fixed, point-to-point operations may employ transmitting antennas with directional gain greater than 6 dBi provided the maximum peak output power of the intentional radiator is reduced by 1 dB for every 3 dB that the directional gain of the antenna exceeds 6 dBi."

Better range increase..

[Spackler]

The best way to increase the range of the linksys router is to not use a linksys card with it.

Switching from the linksys card to an Orinoco more than tripled my range! It also made me realize that the linksys router signal _was_ hitting the street (I thought it wasn't reaching my couch with the old card), and enlightened me to "War driving". If your having range problems in your house, it is more likely your card.

Good for overcoming line losses

[rcw-work]

At 2400mhz, 3-4db is equivalent to the loss in 45-60 feet of LMR-400 coax (or 12-16 ft of RG-58), according to this calculator [timesmicrowave.com].

For those that would like to put an 802.11b antenna on their roof without worrying about weatherproofing their access point, this may be just the thing.

This is an elementary SNMP set

[arivanov]

Browse the MIB supplied by Linksys on their web site and do the same with scotty. No real rocket science here. It is as elementary as it can get.

No need of the windows executable

Re:Rather Clever, Really...

[Anonymous Coward]

Several watts of effectively radiated RF at such a high frequency carries a serious risk of tissue damage through close-proximity RF burns. Nothing that would kill you but it'd hurt like a mofo, like most RF burns.

The jury is still out on prolonged exposure, but I wouldn't want to be near one running even 1 watt for a long period of time.

Re:SNMP?

[T-Punkt]

For *nix I suggest net-snmp (aka UCD-snmp):

http://net-snmp.sourceforge.net/

bad engineering practice

[lophophore]

Since the 802.11b communications link is two-way, increasing the transmit power of only one end (the access point) is not going to buy you a whole lot. To increase the range, you need to either increase the effective power on both ends, or, more simply, put the access point up higher.

A higher gain antenna on the access point would help with both transmit and receive, and this is another option, however, I think that this might be illegal in the US.

Also, it is useful to recall that microwave ovens operate on 2400 MHz because this is the most efficient frequency for heating water. One watt is enough to cause some RF heating and potentially be hazardous to you health. Don't look at the business end of that yagi!

Re:Are there similar registers for the pcmcia card

[SpectreGadget]

For many of the pcmcia cards (probably not the cheap ones), a client utility is usually included that allow you to change the output levels. I actually turn mine down at work as I have an AP at my desk and I'd like to keep my hair. ;0) Really though, I'm only using it for testing so 1mW on both ends works just fine and reduces the chance of an attack (both internal and external, i work at a big company) since the range is reduced.

Re:Wireless Phone interference

[Anonymous Coward]

Had the same problem, just make sure you seperate the Siemens base unit and the AP. That solved the problem for me!

Re:Wireless Phone interference

[krangomatik]

If a cordless phone is killing your wireless connection the problem is usually that the phone is a frequency hopping spread spectrum device, which don't play well with 802.11b networks. Here's a snippit from a Cisco Wireless LAN FAQ about their Aironet line of products(they're the Cisco 802.11b APs and cards):
----
Q. Would another vendor's frequency hopping (FH) equipment sitting next to our direct sequence (DS) equipment have any negative effect?

A. Yes. By its very nature, an FH product hops across the entire band. It will therefore spend time encountering interference from our product and causing interference to our product. There is no way to control where an FH unit will hop. Blocking out the portion of the spectrum that the equipment uses would be a possible solution, but in the United States the FCC does not permit FH devices to limit their hop--they must hop across the whole band.

Q. My WLAN system is seeing interference from a cordless phone. What can I do?

A. Most cordless phones are FH devices, with the potential problems inherent to such products. See the answer above for more information.
If the phone is a DS device and lands on exactly the same channel being used by the Cisco Aironet equipment, and if the phone is close to the equipment and you are using both simultaneously, then you will have problems. Try any or all of the following suggestions:

Change the location of the Access Point and/or the base of the cordless phone.

Switch to channel 1 on the Access Point. If that doesn't work, try channel 11.

Use a remote antenna on the client card if it is a PCI- or ISA-based card and you have that option.

Operate the phone with the antenna lowered, if that is an option.

If all else fails, use a 900-MHz phone instead of a 2.4-GHz phone.

----

If you'd like to read the whole faq check it out at http://www.cisco.com/warp/public/102/wlan/radio-fa q.html [cisco.com].

Re:MIB hackery

[mmmbeer]

Nice job Danish. For noobs who just want to juice their WAP11 (192.168.100.250 is the IP addy of the Access Point):

apt-get install snmp
snmpset 192.168.100.250 public .1.3.6.1.4.1.410.1.1.8.8.0 x "80 80 80 80 80 80 80 80 80 80 80 80 80 80"

Re:Wireless Phone interference

[stripes]

2.4Ghz Seimens wireless phone and whenever I use that it cancels out my computer's wireless access

I have the same phone (three of them), and working 802.11 (with a Cisco 340, until it died, and then an Airport 'cause my office is close to the apple store...and it looks cool so my wife will let me put it in more "public" parts of hte house).

Try changing the channel you broadcast on, and try the "reduce interference" setting on your iBook. Also if you don't have really good signal before using the phones try moving things around a bit.

Does anyone know if this hack will affect this behavior (worse or better)?

Since it boosts the base station, and not your laptop's output, it may not help (you might be able to see it, but it may not see you), also the boost looks kinda small.

I would try it myself, but I use my iBook's Airport card for wireless access and can't run the program they use from my Mac, which would mean getting a PC wireless card to perform the hack.

I don't think you need to try the hack from a wireless machine, just something with IP access to your WAP base station. Plus while the instructions for the hack are for using a PC tool, it is all done using SNMP, so you can grab some of the SNMP tools for Mac OSX and translate the instructions yourself. It might not buy you much range, but it would be a learning experience...

Re:Wireless Phone interference

[meatspray]

nope have the $200 panasonic phone totally blasts my wireless if i'm more than 20ft away from it. (indoors ymmv) i'm going to get another ap and run ethernet into the living room (the only room far enough away that i loose connectivity.