A system includes a first plurality of blockchain nodes including first network nodes external to a vehicle and second network nodes internal to the vehicle, the first plurality of blockchain nodes maintaining a first distributed blockchain ledger; and a first computing device. The first computing device is programmed to transmit a first request to the first plurality of blockchain nodes requesting access to a vehicle network via a communications access port in the vehicle; demonstrate a first proof of work by responding to a second request from the first plurality of blockchain nodes; and receive, based on a first majority of the first network nodes and the second network nodes in the first plurality of blockchain nodes accepting the first request, first authorization specifying access to the vehicle access via the communications access port.