There is media.peerconnection.enabled in about:config. When set
to false, WebRTC doesn't work but I'm not sure if there isn't
anything left active.
Also uBlock has an option "Prevent WebRTC from leaking IP adresses".
WebRTC should be disabled by default or firefox should ask
explicitly like with webcam-access.
There have already been reports where sites use your browser as a
peer in a P2P-network (without your consent). This can be really
problematic depending on where you live.
Yes, oddly enough. It can be used by a website you visit to gain information about your local network which turns out to be incredibly effective for fingerprinting.
The best solution is running the VPN client in your router. That way, your machine can't see its ISP-assigned public IP address.
If you're using a workspace VM, you can run the VPN client in a pfSense VM, which is functionally equivalent.
If you're not using a workspace VM, and can't run the VPN client in a router, you can run the VPN client in a pfSense VM. You bridge the WAN interface of the pfSense VM to the host LAN adapter. So then the host can't use it. And you configure the LAN interface of the pfSense VM as host-only. So now the host machine (your workspace) can reach the Internet only through the VPN client in the pfSense VM.
Or you can just make sure that WebRTC is disabled.
Also uBlock has an option "Prevent WebRTC from leaking IP adresses".
WebRTC should be disabled by default or firefox should ask explicitly like with webcam-access.
There have already been reports where sites use your browser as a peer in a P2P-network (without your consent). This can be really problematic depending on where you live.