i found it very easy to grab a couple of pre-built containers.. im using deluge and gluetun .. im sure theres a transmission container out there also.

setup your auth info in gluetun, point your deluge/trans container at gluetun for its network and youre done.

Thank you for taking the time to put this together and post it.

Gluetun is the way. Get a transmission docker container, set up a gluetun docker container, set the gluetun container as the network for the transmission container.

Viola, you have a perfectly working VPN with a kill switch.

On BSD you use FIBs to declare process specific routing tables, on Linux you use firewall marks to do the same, then just route all trafik through the vpn uplink and deny any other.