Help! I've been scammed. Is it possible to trace a computer via the MAC address??

[alkemyst]

your definition of common is different than mine.

I said it's totally not uncommon. That's at the upper limits to me.

In the end all I can provide is they happen.

believe it or not.

 

[spidey07]

E thugs don't step down. Both are right and both are wrong, but neither will accept that

MVbighead 2 posts above sums it up best.

quote -->
"MAC address are ***intended*** to be unique. It is extremely rare to find a case where a MAC address is assigned to two separate pieces of hardware."

This thread was still interesting to me because I always believed the textbook lesson that manufacturer burned in mac IDs were unique, but obviously, things and ppl can fuck up, even intel.

You run into duplicate MACs when you get into load balancers and redundancy scenarios where you WANT different devices to have the same MAC for failover purposes. Also devices that have a "bank" of MACs they use and you select what bank to use - if you select the same bank and they're on the same L2 network you could see duplicate MACs

 

[alkemyst]

no...wrong. These were hardcoded devices.

Please pull through.

 

[mvbighead]

As I said before, MACs are intended to be unique... and I'll add that in 99.99% of cases, they are.

As to load balancing scenarios, that's all fine and dandy. The point is MACs are intended to be unique. IP addresses are bound to MACs, and the MAC address table in the switch has one path to go to get the data to the designated MAC. Duplicate MACs defy uniqueness, and are absolutely NOT intended.

The biggest point in this whole shtick is that MACs are intended to be unique. Hell, the word unique appears 9 times in the wiki article in relation to MAC addresses.

http://en.wikipedia.org/wiki/MAC_address

Do exceptions happen? Sure. But those are the exception, not the rule. If you hand someone a laptop with an Intel Pro 1000 NIC built in, and then hand them a stack of 100,000 laptops/desktops with the same exact type of Intel Pro 1000 NICs built in, the odds of them finding one with the same address is less than 1%, I would be willing to bet.

The answer to the OPs question is that yes, MACs are unique in that regard. Only if the manufacturer fouled up and duplicated that MAC would that not be the case. Thereby meaning that commonly MAC addresses are unique, and that it is uncommon for someone to be able to find an exception to this rule with two physical devices.

Virtual devices, aggregate MACs in a redundant framework, etc. are part of the design of an industry level network framework, and outside the scope of this argument.

 

[alkemyst]

yeah...thanks for wiki.


wiki wiki wow.

 

[airdata]

So according your little text book, yeah...unique. According to the real world, like much of what you will find in those texts....very different.

He belittled text books in his first post, so posting a wiki link surely isn't going to help here.

 

[mvbighead]

yeah...thanks for wiki.


wiki wiki wow.

Damn you're a tool. You do realize that there are people out there that know more about this stuff that you do, right?

Yes, I referenced a Wiki. Holy shit. That's just crazy.

Here's more, take your pick:

http://www.webopedia.com/TERM/M/MAC_address.html

http://www.smallbusinesscomputing.c...hats-a-MAC-Address-and-How-Do-You-Find-It.htm

http://www.wisegeek.com/what-is-a-mac-address.htm

http://kb.iu.edu/data/alfq.html

My problem is your insistence that it is not uncommon to find duplicate MAC addresses. That statement is false, 100%. It defies the principles of networking. If items are not unique, routing simply cannot take place. Give two systems the same static IP address, you have a problem. The same MAC, similar problem. Hell, switches are designed to detect these anomalies and quite often disable a port that registers an identical MAC as another port to avoid switching loops.

Errors have been made in a manufacturing process that created the situation of which you speak. Either that, or high level networking infrastructure components designed to establish redundant links, VMs that have been improperly configured by an administrator, or physical NICs that have the option of a manually configured MAC that is configured incorrectly. But by and large, MACs are unique.

By and large VINs are unique, but if the system that generates the VIN numbers screws up... does that make them not unique in principle?

Sorry, but your ridiculous snarky comments about a guy being a helpdesker just prove the arrogance you have. Most people in IT don't start out as network admins. Gotta get your foot in the door in most places to move up the chain. And to walk into an IT manager's office and emphatically tell him that (to use your words) "It's not totally uncommon in huge rollouts to have two devices share the same MAC, hence why almost all modern devices allow the user to reassign a MAC." would most certainly get your application to land in recycling BIN.

Your first comment set your whole stance in the wrong direction, but God forbid someone tells you you're wrong. Oh heavens, not that.

 

[tdawg]

I guess this shouldn't be surprising considering your user name, but are you actually suggesting that the OP commit a felony?

Money laundering FTW!

 

[bret]

Still have the bills? Buy an item for near $100, each at a different store. Return the items a week later to their respective stores and receive legit cash in the refund. If they're "really good counterfeits" as said by the bank, it'll probably fool Floe at Walmart.





Nice first post. How 'bout you go peddle your fraudulent BS anywhere else but here.

Don't let the door hit your ass on the way out.


esquared
Anandtech Administrator

good thing your banned. and second your more of an idiot than i thought. if a bank receives fake money they are legally bound to keep the money and are not allowed to return it to you.

as for the poster there is software out there that will track your computer if its stolen. but other than that... not that i know of.

 

[Glob]

your definition of common is different than mine.

I said it's totally not uncommon. That's at the upper limits to me.

In the end all I can provide is they happen.

believe it or not.

See, this is the problem. This guy believes himself to be an authority on something he obviously isn't, and is misrepresenting himself as such. I find it sort of pathetic. Go get the knowledge, and when you have, you won't need to talk down to others to feel good about yourself.

You still don't get it; no one is asking you anything or seeking your consult. We are trying to bring you back to reality, and, I assume, dissuade any newbie networkers from believing any of the nonsense you are bringing to this discussion. If I didn't value my anonymity and company's proprietary information so much, this discussion could get a lot more interesting. I'll leave it at this: MAC address individuality is important to maintain in a global Ethernet network.

As far as your claim of having encountered 6 instances of duplicated MAC addresses on a LAN (assuming they were the original, "burned-in" MACs), I'd strongly suggest you start grounding yourself during storms, because you are way overdue for a lightning strike. Alternatively, stop buying equipment from Chinese counterfeiters. There is obviously a problem with either your vendor's manufacturing process, or your perception of reality.

I honestly don't know why we're still having this discussion. It is very much a closed subject in the real networking community.

 

[Narmer]

OP, have you tried "selling" another MBP and trying to see if the scammer will bite again?

 

[alkemyst]

Errors have been made in a manufacturing process that created the situation of which you speak. Either that, or high level networking infrastructure components designed to establish redundant links, VMs that have been improperly configured by an administrator, or physical NICs that have the option of a manually configured MAC that is configured incorrectly. But by and large, MACs are unique.

lolz...take a breath kid. This was EXACTLY my point though. You can't say they never happen. Then say bullshit when someone does have examples of it...then say oh that's just manufacturing error.

Shit happens, that was the point. Keeping tunnel vision to reality is going to set you up for failure.

Sorry, but your ridiculous snarky comments about a guy being a helpdesker just prove the arrogance you have. Most people in IT don't start out as network admins. Gotta get your foot in the door in most places to move up the chain. And to walk into an IT manager's office and emphatically tell him that (to use your words) "It's not totally uncommon in huge rollouts to have two devices share the same MAC, hence why almost all modern devices allow the user to reassign a MAC." would most certainly get your application to land in recycling BIN.

Your first comment set your whole stance in the wrong direction, but God forbid someone tells you you're wrong. Oh heavens, not that.

I wasn't wrong though and you are beating a dead horse insisting I was.

If you are in the habit of deploying 10,000+ client builds you will end up seeing a duplicate MAC in your lifetime probably a few times. To me that is 'uncommon' not 'rare'. However, it's a very subjective thing these terms.

 

[alkemyst]

See, this is the problem. This guy believes himself to be an authority on something he obviously isn't, and is misrepresenting himself as such. I find it sort of pathetic. Go get the knowledge, and when you have, you won't need to talk down to others to feel good about yourself.

You still don't get it; no one is asking you anything or seeking your consult. We are trying to bring you back to reality, and, I assume, dissuade any newbie networkers from believing any of the nonsense you are bringing to this discussion. If I didn't value my anonymity and company's proprietary information so much, this discussion could get a lot more interesting. I'll leave it at this: MAC address individuality is important to maintain in a global Ethernet network.

As far as your claim of having encountered 6 instances of duplicated MAC addresses on a LAN (assuming they were the original, "burned-in" MACs), I'd strongly suggest you start grounding yourself during storms, because you are way overdue for a lightning strike. Alternatively, stop buying equipment from Chinese counterfeiters. There is obviously a problem with either your vendor's manufacturing process, or your perception of reality.

I honestly don't know why we're still having this discussion. It is very much a closed subject in the real networking community.

So you are saying my brother, one of the people that has encountered this is not an authority on it?

He not only edits for Cisco Press, but is also a dual CCIE.

I don't know what "vendors" you are talking about in this though...manufacturing is outside that. If I buy 10,000 Intel NICs from CDW vs MoreDirect chances are they are coming from the same source.

If that 'batch' had a probem, then I will probably see it. If I was buying onesy-twosy, then probably not.

Oh and BTW, I don't know where you are going with the textbook stuff again. No one has said that encountering a duplicate MAC did not cause problems...in fact it had to be corrected and was causing issues that sadly weren't assumed to be due to having a duplicate MAC at first. It's a huge problem.

My point was, and I am correct; is that although MACs are supposed to be globally unique, they are not in practice. It's not a common occurance though.

Also on any separate network that duplicate MAC will never be known.

 

[Emulex]

Nah there's alot of folks that fry bios' or replace motherboards and don't re-tattoo the correct mac address.

iirc i have a few mobo's that decided to go to 00:00:00:00 so i just picked a number out of my hat. the likely hood that a collision would occur in my subnet is zero since i picked manufacturers i'd never use.

but it's a real situation.

Think about it - what if the sql server that pumps those mac addresses out crashes. logs aren't perfect. you lose the last one, you can produce a dup mac within a lot.

trust me - it happens. the QA should catch it but not always.

imo the easily forged mac address makes it nearly worthless. If a router sees a duplicate mac ; it should probably shutdown the port and notify you.

I personally check the mac of every nic before i put it on the net - fast port forward is a nasty nasty thing to encounter.

then you have fools that bring in gear with C0:FF:EE:EE DE:AD:BE:EF etc mac-override in software- you're not the only one that does that. mostly just to see my own pc at work stand out quickly

 

[spidey07]

Alky you're way off here.

It's extremely rare to have duplicate mac. It does happen, but it's extremely rare.

 

[mvbighead]

My point was, and I am correct; is that although MACs are supposed to be globally unique, they are not in practice. It's not a common occurance though.

Nope, pretty sure your point was this:

Mac Addresses aren't unique. It's not totally uncommon in huge rollouts to have two devices share the same MAC, hence why almost all modern devices allow the user to reassign a MAC.

I still don't understand how one can say that it is "not totally uncommon" to have two devices share the same MAC, then go on to say duplicate MACs are "not a common occurrence." Those two statements are pretty much the exact opposite of one another. Not uncommon is common, no?

My biggest issue, once again, is that you came on here spouting off on someone who is referencing the intended design of MACs to be unique, and claiming that they are unique. All texts suggest that they are. High profile IT industry magazines suggest that they are (or should be). Now your argument is based on semantics. To have one (or six) duplications totally invalidates the intended design of MAC addresses.

Not saying I don't see you point, as 1 or 2 (or 6) anomalies certainly does mean that MAC address aren't 100% unique, but in theory they should be, and in practice they are 99.99%+ of the time.

 

[alkemyst]

MY POINT is from my perspective. For most people, even seasoned network engineers; they will never encounter a duplicate burned in MAC.

I happen to have friends that deploying 1000-5000 clients is considered a small job.

These were my resources when I was studying for my Cisco certs.

It's insane how much of a debate this caused. My argument is not one of semantics, mvbighead, my argument is of real world, in the wild encounters. Keep in mind this '6' times is just my experience. You and I could both very well have an identical MAC and never have it cause us an issue.

Yes, by design MACs are to be globally unique. Yes, most people should never be struck by lightning...yet some get hit several times in their lives doing nothing high risk to promote it.

 

[JackMDS]

Since the OP "disappeared" from the thread 8 days ago

I just thought that people would to familiarize themselves with this term.

http://www.thefreedictionary.com/perseveration

 

[gsaldivar]

Since the OP "disappeared" from the thread 8 days ago

I just thought that people would to familiarize themselves with this term.

http://www.thefreedictionary.com/perseveration

hahahaha

 

[seepy83]

Since the OP "disappeared" from the thread 8 days ago

I just thought that people would to familiarize themselves with this term.

http://www.thefreedictionary.com/perseveration

I never thought this is what I would find when I saw more responses to this thread. Well played. :thumbsup:

 

[Glob]

Since the OP "disappeared" from the thread 8 days ago

I just thought that people would to familiarize themselves with this term.

http://www.thefreedictionary.com/perseveration

I know, I know. Every day I read this thread again, I think of this, but I can't help myself:

I was thinking of making this my new signature:

MACs were never billed as unique unless back in the old Class A, B, C days.

Because IP class has something to do with L2 broadcast domains!

 

[alkemyst]

Because IP class has something to do with L2 broadcast domains!

What I meant [and you don't get] is in today's world those that know would never stake their life on a burned in MAC being unique out in the wild.

 

[zeos]

9.2.3 Uniqueness of address assignment

An issue to be considered is the nature of the device to which uniqueness of address assignment applies.

The recommended approach is for each device associated with a distinct point of attachment to a LAN to
have its own unique MAC address. Typically, therefore, a LAN adapter card (or, e.g., an equivalent chip or
set of chips on a motherboard) should have one unique MAC address for each LAN attachment that it can
support at a given time.

NOTE—It is recognized that an alternative approach has gained currency in some LAN implementations, in which the
device is interpreted as a complete computer system, which can have multiple attachments to different LANs. Under this
interpretation, a single LAN MAC address is used to identify all of the system’s points of attachment to the LANs in
question. This approach, unlike the recommended one, does not automatically meet the requirements of
IEEE Std 802.1D-1998™ MAC bridging.

Just wanted to kick the hornet's nest.

http://standards.ieee.org/getieee802/download/802-2001.pdf

 

[m1ldslide1]

Agree with Glob and others - MAC's are intended to be unique, and I've never heard of a duplicate although I believe it is possible. The statement that workstation/host MAC's commonly need to be changed in large deployments due to duplicates is false. I'm sure its happened a few times in the history of ethernet, but so have sun spots.

<--- Been a network engineer for a bunch of years, planning to fail the R/S lab in a couple of weeks.

 

[alkemyst]

Saying something is not uncommon doesn't imply it's a common thing.

I'd not say it's extremely rare either based on what I have witnessed.

Like I said most will never encounter it.