Can my ISP block my connection so that my laptop can't detect a LAN?

Question

I recently moved into a room in a dormitory. This room has a wired internet connection.

The problem is that when I plug the cable into my laptop (HP Pavilion g15) it doesn't detect anything, it is like there is no cable and I tried everything from changing the cable to trying my laptop in another room.

It is actually a problem in the whole building, some students can connect, others can't. My friend's laptop can connect to the network using my room's connection.

My question is : Can the ISP block a connection so that the laptop can't even detect the network ?

UPDATE : -When I said "like there is no cable", I meant literally, windows doesn't detect that there is an ethernet cable connected.

-I tried all possible scenarios (changing the cable, connecting my laptop in a different room,etc) but nothing worked, it seems that the network allows some laptop to connect from any room and denies other laptops access also from all rooms. I also made sure that my ethernet port is working by connecting it to a router.

-There is no registration process to get access, you just insert the cable.

-I had already notified the housing office with the issue and they contacted the ISP, they have been trying to solve the issue for 3 weeks now and I really don't know why it is that difficult for them.

UPDATE : It has been a year and I almost forgot about this question but here is what happened next in case someone is interested :

The issue persisted for about a month, some laptops were able to access the network from all rooms (i.e. wall plugs), other laptops can't even detect it also from all rooms.

I contacted the people in charge in the dorms but they were extraordinarily slow so I had to do something on my own. I bought a small Wifi repeater, plugged the Ethernet cable into it and it worked right away with no extra config.

After a week or two some IT guys came to the building and installed routers in all the rooms (even for those who had no problem connecting). These were regular routers and they installed it just as I installed the repeater (which I took back to the store).

No one knew what was the original problem. I think they even decided to install the routers because they didn't know what was wrong. The single most strangest internet problem that happened to me.

Answer 1

First, yes, your ISP can block your computer. Can they do it permanently and perfectly? ... probably not, but they can make it hard enough that you don't bother doing it and find another solution.

That's not the real question though. The real question is: "Did your ISP block your connection to their network?" I suspect, unless they believe they have a reason to, that they did not. This suspicion comes from the fact that you're in a dorm, which implies a school, which implies a liberal approach to information access.

I strongly suggest relaying your issue to the folks in charge of supporting the network connections for your dorm or your school (helpdesk, tech support, IT, network ops, etc.). They may have a registration requirement before you connect that you haven't finished going through, or perhaps your roommate by connecting first became the "registered" user, and you need to make an explicit request for your computer to be added / registered / permitted.

If they believe they have a reason not to permit you access, you will learn that most quickly by contacting them.

Answer 2

This doesn't sound like an ISP issue, it sounds like the dormitory may have implemented 802.1X authentication on their Ethernet. If so, your laptop needs to have the proper profile installed so that it can connect to the LAN.

We used this mechanism at a company I worked for, so that visitors couldn't connect their laptops to our internal network (I think there was a separate "public" LAN that they could use to access the Internet).

Answer 3

Talk to the people who run the network (presumably, your campus IT department's helpdesk).

It's quite common for networks to be set up so that only authorized machines can connect. For example, at my workplace, each network port has a list of computers that are allowed to connect to it. By default, that list is "none at all"; my desktop computer has its own dedicated port that no other computer can use, and my laptop also has its own port (though I mainly use the wifi for that). This is done by storing the MAC address of the machine – the hardware analogue of a phone number that's used to transfer data to that specific machine.

It would be unsurprising if your campus network has such a policy. University resources are provided only to members of the university and, more specifically to people who have agreed to the network's acceptable use policy. They will also want to protect the network from people doing dumb things like attaching an open wifi router to it, allowing anybody out on the street to access the internet through the university's connection.

Answer 4

A campus network is not an ISP by every definition - they are providing internet service, but not in the same for-profit, individually billed manner as ISPs commonly do.

Whereas ISPs commonly use some kind of account credentials to grant or deny access to the router (or directly connected computer) at a customer's home, campus networks (and some old school cable networks) commonly use an authorization scheme based on the so called MAC address that is unique to every Ethernet network card (or network port built into a computer's main board). You will need to talk to whoever runs that campus network for instructions on how to get the address of your computer(s) authorized.

Alternatively, there might be 802.11x authentication in use on that network - again, the responsible staff should be able to tell you.

By the way, only plug network cables into jacks where you are SURE they are intended as Ethernet connectors, and for YOU to use. A random RJ45 outlet in a building could just as well be ISDN, or a network you have no business using, or entirely something else. Also, while you CAN change the MAC address of your computer in some cases, DO NOT do that. The trouble and confusion you can cause to network maintainers that way will not make them your friends.

Answer 5

This would not be an ISP level issue - it sounds like an issue with the switches on the other side of those wall jacks - Maybe an issue with port speed/duplex negotiation, or an issue with STP configuration.

Answer 6

Did your try with both straight through and crossover cables?

Nowadays, I would expect every network card to support automatic crossover, but if it didn't, it could lead to the reported behaviour if you were using a crossover cable (or fail only when using a straight through cable, if the wrong cable/setting was used when patching the room).

Computers that are using a network card with automatic crossover would work on the same socket with the same cable, and the 'failing' machine could work on a different socket where the wiring was done differently, or it is connected to a switch supporting automatic crossover.

Answer 7

Have you confirmed that your laptop ethernet connection works on any other network when you plug in with a wired connection?

Sounds like you've already tested with a known good on the problem connection in your room and it's working?

Do you have a manual IP address assigned to your physical network adapter?