A Practical Walkthrough of a Surprisingly Hard Problem

For a task that sounded trivial at first, this experiment turned into a surprisingly deep dive into Android networking limitations, routing constraints, VPN behavior, and how Bluetooth Personal Area Networking (PAN) actually works under the hood.

My goal sounded simple:

Connect an Android phone to my Linux laptop over Bluetooth PAN and route ALL traffic from the phone to the Internet through the laptop — without Wi-Fi, without mobile data, without USB tethering, and without root.

Easy peasy.

Google used to provide prebuild Android images of libWebRTC library, and in fact, it’s (still) the recomended way to use them on its own documentation. But starting on WebRTC M80 release (January 2020), they decided to deprecate the binary mobile libraries, and the reasons were that the builds were intended just only for development purposes, and users were already building it themselves with their own customizations, or using third party libraries that embedded them (where have been left developers that just want to build a WebRTC enabled mobile app?), and they just only provided another build in August 2020 (1.0.32006) to fill some important security holes, in case someone (everybody?) was still using the binary mobile libraries.