Before we start preparing an instance, we need to care about a hardware Wi-Fi interface as probably the most important part of the pentesting platform. There are three main criteria for hardware Wi-Fi interfaces important for penetration testing and thus influence our choice:
- Chipset: The chipset of a Wi-Fi interface should be able to support packet injection mode, which allows us to interact with an interface on a low level and customize transmitted packets.
- Power and sensitivity: This parameter determines the distance between you and your targets—the higher the power and sensitivity, the farther you can stay. But you should take into consideration that higher power consumes more energy and shortens a laptop's battery life.
- Proportions: This parameter does not influence the quality of penetration testing, but it influences the ease of your work. The bigger an interface and the more wires you have, the less comfortable it is to use on-site.
Let's review two typical hardware interface options:
- Built-in laptop interface: In some cases, you can use a laptop's built-in Wi-Fi interface, especially if you install OS and software on a host, not a VM instance or use a bootable USB stick.
The advantage is that it can save you some money on buying an additional interface and makes the whole platform more compact and less suspicious (a laptop with some strange wires and devices or external interfaces always brings more unnecessary questions if somebody operates it in public). Suspiciousness is actually less important for us, because we act as ethical hackers with permission to attack, but the comfort of work is usually very valuable.
The disadvantage is that such interfaces almost always have poor signal strength and can have a chipset that does not support the necessary mode and features, so they're not applicable for penetration testing.
- External USB interface: Typical external USB interface form factors are dongles that should be inserted directly into a USB port or a device that should be connected to a USB port with a cable. Often, external USB interfaces also have external removable antennas.
The advantage is that this type of interface usually provides better transmitting/receiving capabilities and has higher signal power and sensitivity. In contrast to built-in interfaces, UBS interfaces are easily changeable.
The disadvantages of external Wi-Fi interfaces are additional cost, higher battery consumption, and reduced work comfort.
When you choose an interface, the most important parameter should be the chipset. If it does not support packet injection mode, you don't need it. The other two criteria we leave to your taste.
You can easily find lists of chipsets that support packet injection mode on many websites and forums in Internet, but we would recommend you first get familiar with the manuals written by the Aircrack-ng team at their website:
In our experience, the most popular suitable chipsets are as follows:
- Atheros AR9271
- Ralink RT3070
- Ralink RT3572
- Realtek 8187L
If you don't want to spend time on comparing various Wi-Fi interfaces and their parameters, we can recommend our favorites from the company Alpha Network:
- Alfa AWUS 036 H on RTL8187 chipset
- Alfa AWUS 036 NHR (v.2) on RTL8188RU chipset
TP-Link TP-WN722N is a very good USB dongle interface. You can see all those three interfaces in the following image:
Our "workhorses" for Wi-Fi pentesting
If you already have a Wi-Fi interface and you are not sure if it supports the packet injection mode, you can test it with the Aircrack-ng suite using the following manual: