how to make an ultra-long-range wifi antenna
If you’re the red team pentester it's always useful to carry an ultra-long-range wifi antenna. which has high gain as well as high reception, suppose you’re a long distance from your target and have no time to walk towards it what you can do is just point the long-range antenna facing your target and now you can hack it easily.
In this guide, I’ll demonstrate to you how to build cantenna (can+antenna) and will give you some bonus tips as well. Keep in mind that this is a directional antenna you’ll need to point is towards your preferred destination.
Things you’ll need
- metal can (aluminum, copper, steel, iron, etc.)
- RP SMA male connector (compatible for wireless adapter)
- wireless adapter ( with removable antenna)
- USB extension cable
- copper wire (small piece)
- soldering iron
I have seen quite a lot of people using pringles can as a cantenna and it is also featured in movies quite a lot of time, now the pringles can cantenna is not that quite efficient (a metal used in the can is not quite good it can do better) if you really wanna achieve the efficiency of your cantenna what you can do is choose a metal can which should be of right length and diameter, here's the calculator I used. put the frequency you want and diameter of your can and you’ll be given the values. ‘802.11b and 802.11g WiFi operates between 2412 MHz and 2462 MHz. The TE11 cut-off frequency should be lower than 2412 MHz and the TM01 cut-off should be higher than 2462 MHz.’
you need to be very precise with the length and diameter of the can. you can find metal cans in your nearby stores and toilet brush holder works as well.
once you have a metal can of the right length make a hole from the bottom reflector of the can, you should be precise while making the hole at a distance of λg/4 from the reflector, these values are available in the calculator.
once you got the hole take the RP SMA connector and solder copper wire to it (this part will be inside) the length of the copper wire should be Wavelength λ/4 which will be given by the calculator.
now solder the RP SMA to the can through the hole make sure copper wire doesn't touch the can only the outer part of the connector should be in contact with the can, here you can attach the connector with help of soldering or you can attach it via screws. Also, make sure you’re not bending the copper wire it should be straight.
And here we have a long-range wifi cantenna connect your wireless wifi adapter to the SMA connector, you can connect to your wireless adapter through a USB extension cable for better mobility. Now point cantenna towards your target.
If you really want to maximize your range and also if you have a spare satellite dish antenna. The main reason satellite dish works best here is that they’re parabolic in size and will work best for our project.
attach your cantenna at the focal point of your satellite dish which should be close to your LNB ( you won't need LNB here as it works for C band frequencies)
now to find the focal point of your satellite dish you can cover it with reflective paper which you can find in nearby stores, take the dish in sunlight and try to find a beam focused point by your hands and the point will be the focal point of the dish, this is the easiest way to find focal point if you don't wanna go through maths.
now it is a bit tricky with the satellite dishes to get their direction to point towards you will need to be pointing dish facing down to get the access point in your front. also, make sure you’re in the line of sight with your target.
after you attach your cantenna it’ll look like this.
Let's see how the cantenna works
the traveling waves are captured by the copper wire which is the length of the wavelength λ/4 so that's why the diameter and length of the can are so important here.