One problem is that the ECUs are fairly dumb, they each have a limit on how fast you can send CAN frames to them without overflowing receive buffers. The protoc

One problem is that the ECUs are fairly dumb, they each have a limit on how fast you can send CAN frames to them without overflowing receive buffers. The protocol to reprogram them starts by asking the target ECU how much of a delay is needed between each frame then needs to keep to quite tight timing constraints when sending the new flash image, I have written a Linux network protocol module to do this.