dslreports logo
site
spacer

spacer
 
    All FAQs Site FAQ DSL FAQ Cable Tech About DSL Distance DSL Hurdles »»
spc

spacer




how-to block ads



This Section
No, and here's why:

As far as I know, there are three major ways that cable companies allow cable modems to access their network:

1.) Filters/Traps:
Some cable companies don't care about the MAC address of your cable modem. They prevent your modem from talking back to them by installing a filter and/or trap on your cable line at the tap.

When you get your service activated, they come out and remove whatever they need to.

This is not used often because it's very easy for people to steal cable modem service.

2.) HFC (Cable Modem) MAC Authentication:
In this case, the cable company would authorize your cable modem by it's MAC. Every DOCSIS cable modem has one, and if you look at yours, it should have a sticker with an "HFC MAC". When your modem boots up, it attempts to talk to your cable provider, and the provider will either grant or deny it access based on it's MAC address.

3.) HFC (Cable Modem) AND NIC (Network Card) MAC Authentication:
Some cable companies, for some reason, also authenticate the network card in your computer. First it will authenticate the Cable Modem, and then when your computer attempts to get online, they'll check and make sure that you're still using the same computer/network card/etc that you've always used. If you've changed your network card or installed a router, they will block your access.

I'm not sure exactly why they do this, but I'm guessing that this is partially how they prevent you from sharing your cable modem on a network.

This is also why most routers have a "MAC Address Clone" feature. If you tell your router to clone your network card's MAC Address, it makes your cable provider think that you're still using the same computer/network card to access their services, and therefore they allow your router on the network.

Now, the reason why it wouldn't get you free cable: When you clone an address in your router, you're cloning a NETWORK CARD, not a CABLE MODEM.

The only way you could get free cable modem service this way is by somehow changing the MAC address of the CABLE MODEM to one that has been provisioned (authorized) already. DOCSIS cable modems cannot be modified in this way.

Now that I think about it, if any cable companies out there authenticated by Network Card MAC Address only, and not cable modem, this might work, but I doubt there are any providers out there that dumb.

Feedback received on this FAQ entry:
  • 5.1 Provisioning (Activation) ·How does my provider activate my modem? ·Is there any way to get free cable modem service? ·If I copy a Valid MAC address in my Router could I get free service? How does my provider activate my modem? (#3338) Please note that the following information applies mostly to DOCSIS systems only. I do not know how other cable systems work, only the one I work in. Usually, if the cable modem is being installed by a technician, when he arrives at your residence, he calls his dispatcher and tells him or her the HFC MAC address of your modem. If you look at your cable modem, you will see a string of numbers on it somewhere starting with 00-90, 00-20, 00-00, or something similar. (Those numbers vary with the manufacturer of the modem). If you are doing a self install, you are usually instructed to call your cable company and read the number off to them. They then bind it to your account and activate it. Every cable modem manufactured has a unique MAC address (just like every network card or network device). This MAC address is bound to your account, and if your account is active, the cable modem is allowed to talk on the network. After your modem is provisioned or activated, you then hook it up to your cable and plug it in. (Continue on to Modem Boot Up...) feedback form feedback form Any feedback you provide (corrections, updates or suggestions) are sent to the owner of this FAQ and anyone else involved in writing or editing this item. by Raydr last modified: 2002-02-27 18:44:53 Is there any way to get free cable modem service? (#3378)

    2009-12-01 00:16:00

  • HFC MAC addresses can be modified using modified firmware.

    2009-08-11 04:02:46

  • I work for a cable company and I have a trillithic DSPi. It's a signal meter with a built in docsys 2.0 cable modem; however the modem has two permenant mac adresses, and can spoof mac adresses and cpe mac's. Even though I can clone the mac adress of a cable modem our system only allows one cable modem online at any given time, this means that if you for some reason decided too spend 2500 dollars for a system that can clone mac adresses you would have to offline the modem that you were clonig and then log on with the spoofed mac modem. If you don't the server will just disconect you and your modem will go into a loop finding down stream, up stream, and trying to obtain an IP. I believe that on docsys 1.0 systems you can get an ip on two modems with the same mac at the same time, but I'm not sure about that as I have never worked on a 1.0 system. are there even any 1.0's left or did everyone go 2.0 and 3.0?

    2009-04-10 20:40:04

  • DOCSIS modems (specific models, motorola surfboard 3200,4100,4200 & 5100)actually can have their internal MAC address changed.

    2007-10-31 13:29:16



Expand got feedback?

by Raydr See Profile