# Browser Fingerprint：Media Device
WebRTC is a browser plug-in that enables audio and video calls within web pages via a direct P2P connection, eliminating the need to install additional plug-ins or other native applications. To make this plug-in work, WebRTC connects to your media devices, such as microphones, cameras, and headphones. Websites can take advantage of this tracking mechanism in two ways:
- Device enumeration
- Media device ID tracing
You can view both authentication methods on the Browser leaks test website.
# Device enumeration
The method relies on retrieving a complete list of microphones, cameras and headphones that the user has installed. While this number alone is not enough to explicitly target users, it can still make a difference.
In the Migratory Bird browser, simulation has been done based on the number of different media devices in the browser profile.
# Media device ID
For WebRTC to work properly, websites need to know more than just the number and type of devices you have. In order to establish perfect real-time communication, unique device identifiers are also necessary. You can think of your device address. Of course, browsers won't let websites know the full model name of your device; instead, they'll use a hash value called the device ID. At the same time, websites can also use these values for user identification.
Because the media device ID is unique to each user, it is a particularly effective technique for browser fingerprinting.
In the Migratory Bird Browser, the real device ID of each device is masked.