Comcast XFINITY → [Connectivity] MAC Address Scam?

Comcast is telling me that my new Motorola SBG6580 has a black listed MAC address. This seems extremely unfair to me, and they even have the audacity to suggest that I should just give them the modem I paid $80 which was still in the box... From what I'm reading this happens to people all of the time, and the ISP never attempts to chase down the other folks using duplicate MAC addresses.

Can someone help me understand this? Is there any way to hassle Comcast into launching an investigation? I can't afford to buy another modem if I can't get a refund, and honestly, Comcast should have to help me deal with this!!!

Where did you buy the modem from?

You say this is a new modem and then say you can not get a refund.

Why could you not get a refund if the modem was just purchased?

Why could you not return the modem if it was just purchased?

Could have been purchased from a shady seller? private person selling on e-bay comes to mind.

It's not a matter of a duplicate MAC address.

The modem was either stolen and offered for sale or was being used by someone who stopped paying for their service, kept their rented modem instead of turning it in, disappeared beyond the reach of Comcast and then sold the modem or gave it away to someone who sold it.

If this is true I'm surprised Comcast hasn't shut off his service yet for lack of compliance.

Shut off whose service?

They didnt have to shut it off as it was never activated. Clearly going to be a ebay craigslist type of modem.

You have to keep in mind its not a duplicate mac address. It is the only mac address. Think of it as a serial number on a car. No such thing as a duplicate.

This is easily fixed... You can log in to the modem and clone a MAC and the only MAC the ISP will see is the cloned MAC. This should be absolutely no issue... I have been doing this since the early DSL days and still do it all the fam ISPs... you can create a MAC with a simple script, google it.

The issue is resolved.

Do NOT buy modems online, repeat; Do NOT buy modems online. Period.

This forum is loaded with horror stories of modems purchased online only to find out they are either stolen, unreturned equipment, or tied to an account in collections.

Only buy modems at a national brick and mortar chain like Best Buy, Target, or Radio Shack and DO NOT purchase one if it appears to have been returned. Only buy BRAND NEW modems that have the factory seals on the package intact.

Edit: You said you paid $80 for that particular model of modem, well that same modem sells for $149.99 at Best Buy so that suggests to me you got it from a questionable source. If that modem happens to be stolen, in most states you can be criminally charged for receiving stolen property and yes, Comcast can and will report unreturned equipment as stolen to the police departments. Also when you buy subscription based electronics (modems, SiriusXM Radios, prepaid cell phones, etc), they are blocked by the service provider until the store scans the serial number at the register so they are worthless if shoplifted.

You sound pretty sure of yourself here. Log into the cable modem and change its MAC? Provide a screen shot of this. I'm from Missouri - show me.

I deal with this at work all the time and Graysonf is right sorry.

Can't be done on a D1.1 or later cable modem, it USED to work on DSL modems which include a router, and works on almost all routers but it won't fool the cable company.

The mac address is coded onto a hardware chip, it might be possible to eeprom it, or solder on a new chip, but I think the people claiming to do it are talking about routers which allow you to LOG in and change their mac, and in the case of a gateway you can still change the router half, but not the actual modem half, even if you could, the first firmware update and its back to defaults, the cable company has more control over the modem than you do locally without specialized tools.

It used to be part of cable modem hacking a LONG time ago.

Short answer, possible, yes probably no unless you work for some industrial espionage type job, where your job is to spy on the world.

First off, I did some research on the OP's device. I'm calling it a device, and not a "cable modem", because of what I found out.

My information comes from this page

»www.motorola.com/us/cons ··· ,pd.html

No normal "Cable Modem" has four 10/100/1000 Gig Ports on it, along with 802.11n wireless technology.

This tells me that the OP has a "Combo" or "Gateway" device. They don't have a "standard cable modem". What I mean by "standard cable modem" would be one like a Motorola Surfboard SB5100.

Since the OP has not said where they "purchased" this "new Motorola SBG6580" from, anything we post here is just assumptions.

However, I will say that it is quite possible if the OP did purchase it from a friend, or online from Craigslist, ebay, or other like website, there is a good chance that Comcast has "blacklisted" the device. The reasons for that action by Comcast have already been listed by graysonf .

I also agree that there is no way to change the MAC address on a standard cable modem. Modifications to the MAC address of a router are possible however. In fact, I remember back in the day when I first got cable internet (ISP was @home), I had to "clone" my MAC Address of my PC into my router, as the modem would not allow me to go online, as I had to register first using a PC without the router. Once I added the router (which, btw was a Netgear RP114), there was a place in the router to "clone" the MAC of a PC (or you could just type one in). In this way, that MAC was passed onto the cable modem, and all was well. I don't believe one has to do that anymore.

Could the MAC on the router side of the OP's device be modified? I believe so. But, that's not the reason the OP cannot use it.

If the OP does respond, and they tell us that they purchased it new from a brick and mortar store (Best Buy, Wal-Mart, etc), and shows us proof of such transaction, I think it would be time for the OP to return the device for a new one, as it would appear that the "new" item was not really new.

--Brian

Ok, so wanna get technical. You set the cable modem to a bridge mode. Than you set up a router behind it that talks directly with ISP.

A basic cable modem is a bridge.

It has two interfaces. One is coax and has the MAC address that is used to authorize the service by the ISP.

The other interface is ethernet. It has different MAC address but it is not involved with authorizing the modem.

The PC or router you plug into the modem also has a MAC address. But this one is also not involved with authorizing service. It is tied to the assigned public IP address though. The assigned by DHCP public IP address will not change under ordinary circumstances. If you wish to change your public IP address, then you can either change the ethernet card in the PC, spoof a new, different MAC address in the OS TCP/IP stack, or change the MAC address on the router's WAN interface.

There is nothing you can do with your router or PC or its ethernet card that changes the MAC address on the coax side of the modem that is seen by the cable company and is used to authorize the modem. PERIOD.

We have a winner!

If service was never activated then I'm surprised they didn't blacklist the account from being able to activate service for lack of compliance. :/ Glad they didn't though.

Wow! What a flurry of answers. Thanks! OK, let me clarify here -

I never stated I can't get a refund - I purchased the item off of Amazon and have contacted Amazon and the seller. It's a holiday in the states, so I don't expect a response until at least regular business hours tomorrow. We'll see what they say.

Here is my argument - I understand that it would be easy to rip the labels off of a Comcast modem and find a box for it. The issue here is that I also have an official Motorola document which has a label / certificate which is identical to the label on the modem showing serial numbers and mac addresses. It would take an extremely good fake to create a label of authenticity like this one, and frankly, there's another obvious point - you don't receive authentic documentation with a Comcast modem. They just drop it off with their sticker on it. If this was stolen, it would have no documentation linking to it as an original purchase. I don't buy it.

I've been reading into this, and have found several articles of info on the internet which imply that people are sniffing mac addresses and somehow using them and screwing people. Is this faulty info? I'm confused as to how this would work, since it is burnt into the ROM of my device. Whatever the case may be, I've read that others have had this problem, and had Comcast confiscate their devices. I'm not letting them touch mine without some proof.

Thoughts? I'll be hitting the Comcast store tomorrow to bring my authentic documentation to their attention. If they won't remove it from their blacklist, I guess I'll go from there...

Generally it's pretty easy.

All you do is open the modem and then attatch either a usb jtag device or connect straight to a parallel ports with a few resistors and dump the nonvol.

Wait until a person subscribes to Internet, then you load that nonvol onto another identical modem, and you have a clone.

However, this is stupid, since Comcast already has implemented clone detection since forever ago.

(1 year at least)

Hence you may have got that call.

If it's not directly from amazon, or prime labeled, I don't like buying anything from them.
Amazon/prime sellers are too epin, 1 day replacements, free shipping and free returns.

My real question here is how is a gateway from motorola that is doc 3 get blacklisted? So blacklisted seems like it may be a bad term. It is possible, this was someones personal modem they sold, and in doing so never removed from an account they had with comcast. It is also possible that account went over bandwidth limits repeatedly and got some sort of banning. But this should all be clearable at a local office with ID if that's the case. Save for one issue. This creates a conflict in the equitpment system as the same modem cannot be on 2 accounts even if one is terminated. If that is the CASE, have the seller get the modem removed from his comcast account he should just have to call in to do it [I agree its BS, I fight this every day on installs and it pisses me off to no end how stupid it is, but its the way it is and no matter how much we have bitched no one has ever taken the initiative to fix it, generally I am dealing with one person who moved across state lines taking their modem with them but it never works out as easily as it should.]. If you are paying for service, and are live, hook the modem up, you should get a provisioning page once it locks in and firmware updates are done. Enter your account number, and phone number associated with the account [they can even give you this over the phone if you do not have it on a bill]and go through the provisioning setup, worst that can happen is nothing. Best is you get the bug I see ever so often and get the modem provisioned and working and they keep a place holder on your account instead of the modem mac. Good luck.

PS the paper work has nothing to do with what the children claiming to hack modems were saying you do not need it technically to provision a modem it is related to what the government would do when they found out you did it as its against laws. but.. That's a moot point right now.

I am making a couple of assumptions 1 is this modem is brand new to you, and you have not had it online for a few months and been blacklisted for excessive bandwidth usage. 2 is the modem is not stolen from someone who has Comcast working with them to recover them. 3 is that the MAC banning will be done through the local cmts only and not on a regional or national level. try to provision it with the walled garden site and see.

Well, as you already know or know now, Amazon is a storefront operation that handles sales for other merchants.

I have bought several DSL modems via Amazon in the past, all claimed to be new in box. But they weren't. They were refurbished and re-boxed in non-retail OEM white-box packaging.

How do I know they weren't new and previously used? Easy. They were not reset to factory defaults and contained the previous owner's ISP PPPoE login credentials. Otherwise they were perfect, not a scratch on them which leads me to think the cases were replaced with new ones.

This is probably what you have, a previously owned refurbished modem that Comcast has decided to blacklist for some reason. They do not just invent MAC addresses to blacklist - they can't even begin to know a specific MAC address until it is provided to them by someone trying to use the device on their service. Another possibility is they made a typo when they blacklisted another MAC and yours got entered instead.

You are certainly entitled to a refund from the merchant. But you may never get an explanation as to exactly why your modem was blacklisted.

Good luck.

Hello Everyone -

Problem solved. Comcast is completely full of it... The seller sent both them and I a copy of his best buy receipt, and I went into the Comcast store to verify that all was good. The tech at the counter told me that Comcast does not even use this specific Motorola modem, and he didn't see it in the system.

I have no answers, but I have a success story.

As long as I have your assistance - does anyone know of a really good setup guide for the router settings on Motorola SBG6580? I am having a heck of a time forwarding ports through this router. It was sooo easy on my last one. I wouldn't mind a for-dummies walk-through on the firewall, forwarding section, etc.

I can't guarantee how good (or accurate) it is, but: »portforward.com/english/ ··· SBG6580/ might provide you with a starting point.

If the link I'm posting is right, it should pull up the User's Guide for your modem.

I got this by going to the page that I referenced, then clicked on the "get help" button, and selecting "user's guide" from the topic drop down.

»broadband.custhelp.com/a ··· cyY2w%3D

If that does not work, I've "attempted" to attach the PDF to this post. Not sure if that will work or is even allowed. This is the first time that I can think of that I've "attached" anything other then an image.

--Brian

@ NetFixer and plencnerb - Thanks for these!

@ Everyone - thanks for being very attentive. This is a great forum!