In reply to a post by ian72:

It does sound like the real world example of this would be a building that rents out space to various businesses or individuals and as part of that rental provides Internet access (there are I think a number of examples of this these days).

We use a few of these, and if the building supplied Internet tried any of the activities, we would terminate and go to their competition.

Might be useful in a university hall of residence shared internet to "police" the network, but very unlikely in a shared working space. Especially blocking VPNs (e.g. corporate, rather than home user).

This is closest to the scenario I was asking about,. Except building management are not the ISP provider.

The building is rented office spaces to small businesses and the renting and day to day running of the building is handled by management.

However the ISP provider for the building rents one of the offices and all tenants have the option of purchasing internet connectivity from this ISP. They do not have to but pretty much everyone renting office space there does. Vpn connections are allowed.

Sorry for my lack of clarity.

So the answer to my earlier question:

In reply to a post by pluralist:

Who do you pay for your broadband?

Is the tenant of the office.

So the ISP does know you have logged in through the mythical Thompson Construction.

I hope this thread by you is entirely legit, as it's a very strange question to be asking, and whatever the real world setup is that you are supposed to know the Thompson password.

OK well that’s certainly a lot clearer than the invented scenario in your OP!

Basically your neighbouring tenant in a shared space office is reselling you some or all of their pipe. Are they an actual comms provider or are they just some Joe’s doing this on the side?

You can name names I’m sure it’s not against the law.

So the whole question is who manages the network itself. If it is all managed by this other tenant then they could potentially see who is doing what. It is possible that they get an ISP to manage it all for them in which case the ISP might be able to see who is doing what.

In normal circumstances the ISP will see that traffic has come via the Internet link and where it is going to. They would consider the entity renting the circuit to be responsible for all traffic. The renting entity therefore needs to be able to back off liability if there was a court order or similar - normally that would be done by them being able to identify who is responsible for traffic over the connection. Depending on how the other networks connect in this might just identify a single router/firewall that the traffic is coming from or it could identify the individual device - but that is all down to network design.

There is no simple generic answer as there are a number of ways this could be configured and a number of options for who would provide the management and logging.

In reply to a post by ian72:

There is no simple generic answer as there are a number of ways this could be configured and a number of options for who would provide the management and logging.

Contract or other terms of service from the "network provider" should reveal what's what. if they don't and the OP is a director or manager of the company that's getting service from them, then I'd be asking some questions - as you would doubtless with any supplier thats selling you their wares or service.

Otherwise this is probably a bit of a fishing expedition, there's countless variables as you note that makes it pointless.