One question i see popping up more and more is how can you boost your WiFi signal. Its important to know that there is a legal and safe amount you can boost a wireless device to. This is because it can start interfering with other services on or near the same frequencies such as cell towers, satellite receivers and other devices. The legal aspect may be quite clear to stop it disrupting services like cell towers but the safety part is by far more important. With our wireless devices also work on the same spectrum as many off the shelf microwave ovens. By boosting our wireless devices signal by a significant amount can literally turn them into cookers. With enough power they will literally cook your internal organs and cause serious fatalities in yourself and people around you.
With this horrifying idea out of the way lets push on…
Several reasons exist why you may want to boost your WiFi signal. Increase your Network Hacking Range, eliminate WiFi dead zones in your home or even push your signal far enough so that you can pick up a local free hotspot service in your town.
There are 2 ways of boosting a Wireless signal on a device, the first being passive and the second being active.
Passive: With a passive boost the design is altered on the wireless device to boost the devices signal without using additional power (watts). This can mean additional antenna’s or antenna modifications to direct the signal within a closer field to pull or push more power.
Active: With an active boost, more power (watts) are pushed through the antenna boosting its signal. Using this method along with antenna modifications or directional antenna’s can greatly boost the signal.
Generally most devices have a predefined amount of power set in factory to regulation specifications. You will have seen this before if you ever read the back of an electrical device and seen for example “FCC Part 15″. This means it is tuned to preset regulations which are set for safety and disruption reasons.
Most devices are currently blocked on the manufacturers end for doing active boosts (Eircom’s Modem’s as a perfect example) or most bog standard Wireless Interfaces built into Laptops and Smartphones. Luckily there are some devices that can be changed for example the “Alpha USB WiFi AWUS036H Network Interface” (a must have device if you plan to follow me and hack networks). If you currently have one of these devices you can change its broadcast power by using some simple commands done via the Backtrack 5 shell.
- Alpha USB WiFi AWUS036H Network Interface
- Backtrack 5
- Open up a new shell window
- Plug in your Alpha USB device
- Type: ifconfig wlan12 up (replacing wlan12 with your device id)
- Type: cd
- Type: iwconfig wlan12
- Type: iw reg set BO
The BO command sets the country of usage to Bolivia where state regulations allow this device to be operated with 1 Watt of power (twice that of Irish regulations). For US Citizens with also open up your devices channels (1-13).
Please note it is illegal to operate this device outside of FCC part 15 spec so don’t do it unless you are in Bolivia. Also, don’t stand too close to it
Couple this with a device such as a 16dBi High Gain Yagi Antenna and you’ll find yourself sniffing packets on networks you didn’t even know existed.
Passive boosting consists of using alternative antennas or adding additional parts to antennas in the hope to pull in more signal. Personally I have absolutely no experience in passive boosting however i have seen several articles and tutorials with methods to boost WiFi.
Patrick Norton over at Revision 3 has an excellent demonstration on how to make a Windsurfer Passive Booster for your Modem/Router device. It sure looks ugly but apparently it can give a boost of 9-12dB using a non parabolic WiFi Antenna (the ones seen on most wireless modems/routers). You can check the video below to see how its made and where you can find the resources.
The second most popular passive design i’ve seen is the Cantenna. It has developed very little over the last few years however there are numerous companies actually building and selling these devices so i presume they offer some sort of dBi boost on WiFi devices.
http://www.cantenna.com/ sells these devices for around $50 (€39) ex-shipping at the time of writing this article however numerous resources can be found online on how you can make one of these devices yourself. You can find some instructions by following this site: http://www.turnpoint.net/wireless/cantennahowto.html
Once again i have no experience in passive boosting because personally i would rather use an active driven directional antenna to pull and push signal. It just does a better job at amplifying the signal. Remember the old TV aerials we used years back? If you ever used an electric set of TV antennas you immediately noticed the difference and these boosters work in the same way. Also note that these devices not only boost WiFi but also other devices that use the 2.5 Ghz range such as Bluetooth interfaces making them excellent tools when used for example doing Bluetooth Wardriving.
If you have any experience in Passive or Active WiFi boosting or you want to comment on anything else feel free to hit me up on the comment section below.