Beginner's Guide: What's Next?

Hi,
I've been working on my car for a few days now, but I'm stuck and can't seem to figure it out.
So, I received a CAN interface as a gift from someone who didn't need it, and I connected it to my A-Class W169 (manufactured in 2006). On the other side, I have a Linux laptop, which is used to communicate with the car via a terminal.
I'm doing it manually because I want to understand it. Also, I haven't found any software that works on Linux, and...
that provides more information than just speed and other standard codes.
Login successful, able to read hexadecimal data. I can read the first 09 modes and their PIDs, and I've discovered that the car supports EOBD, etc.
Thanks to temporary access to Mercedes' WIS (Workshop Information System), I know that there are 2 CAN buses: one for the interior and exterior lighting, and another...
and CAN-C for the engine compartment. These are wired to the control unit in the ignition switch, which operates the OBD port. So far, so good. Now, here are my questions:

Can I access the control units in the CAN bus via the OBD connector? In other words, can I do this without having to go through the ignition switch, or do I need to tap directly into a CAN bus distributor?
1.1 If I need to access the distribution panel, will I need a different interface?
2. If the answer to the previous question is yes, can I use a diagnostic tool to monitor the CAN-B bus? Ideally, under Linux?

I'm not expecting detailed, illustrated instructions, but I'm really stuck now, and even reading J1979 isn't helping me move forward.

Greetings,
vassloff

Hi.

So, as you've already figured out, the car has EOBD.
This is where the standardized vehicle data comes in (data that is often processed via a gateway).
Basically, you can only make requests and receive a response.

If you really want to listen, you need to connect directly to the CAN bus. Mercedes often has convenient distribution boxes for this. You don't even need to cut any wires.

Unfortunately, I don't know if there is any software available under Linux for your CAN interface. However, here in this forum, there are CAN bus hardware and software available as a complete package: http://www.canhack.de/en/viewforum.php?f=26

Good luck!