Linked by Howard Fosdick on Mon 21st Nov 2011 07:48 UTC
Google Last June, CNET disclosed that Google collects and publishes the estimated locations of millions of phones, laptops, and other Wi-Fi devices. All without their owner's knowledge or permission. Google has finally announced how to exclude your home network from this database. Simply append "_nomap" to its name. Details over at CNET. Left unsaid is why the burden is placed on millions of individuals to opt-out, instead of on perpetrator Google.
Thread beginning with comment 497842
To view parent comment, click here.
To read all comments associated with this story, please click here.
RE[2]: Comment by clhodapp
by Soulbender on Mon 21st Nov 2011 20:55 UTC in reply to "RE: Comment by clhodapp"
Soulbender
Member since:
2005-08-18

If the engineers had known that widespread physical tracking of unique MAC addresses would become reality


In practice MAC addresses are not unique (and don't actually have to be).

And seriously, at least Google is public about collecting this data. It's not exactly rocket science for anyone, private or as a company, to collect this information without telling anyone about it. In fact, i bet there are companies doing exactly this. They might even label themselves "security" companies.

If the engineers had known that widespread physical tracking of unique MAC addresses would become reality, they may very well have designed WiFi differently to protect against it.


Probably not because it would have been impossible or at least not practically feasible. How would your devices locate each other without a unique, visible address?

Reply Parent Score: 2

RE[3]: Comment by clhodapp
by Alfman on Mon 21st Nov 2011 22:32 in reply to "RE[2]: Comment by clhodapp"
Alfman Member since:
2011-01-28

Soulbender,

"In practice MAC addresses are not unique (and don't actually have to be)."

I really would like to know what you mean here, because in practice having duplicate MAC addresses will break things like DHCP and switching hubs which rely on a MAC address's uniqueness.

Sometime adapters make it possible to spoof MAC addresses and do ARP spoofing - which can even have legitimate uses like automatic failover, but then original host will stop receiving packets.

"Probably not because it would have been impossible or at least not practically feasible. How would your devices locate each other without a unique, visible address?"

(Didn't you just say it doesn't need to be unique?)

I'm not here to re-engineer it, but the unique id doesn't need to be static between sessions, it just needs to be unique per AP at any given time.

Reply Parent Score: 2

RE[4]: Comment by clhodapp
by Soulbender on Mon 21st Nov 2011 23:14 in reply to "RE[3]: Comment by clhodapp"
Soulbender Member since:
2005-08-18

I really would like to know what you mean here, because in practice having duplicate MAC addresses will break things like DHCP and switching hubs which rely on a MAC address's uniqueness.


Sure, it causes problem..on the local segment. It wont matter one bit if a company in Stockholm and one in Manila have devices with the same MAC address. A MAC does not need to, and in practice sometimes isn't, globally unique. I know some folks who have managed to end up with two different network cards (from the same manufacturer, of course) with the same MAC address.

(Didn't you just say it doesn't need to be unique?)


Yes, it has to be locally unique but not globally.

I'm not here to re-engineer it, but the unique id doesn't need to be static between sessions


You have a point there, it doesn't have to be the same forever. Of course, the problem is how you define a session. Is it the time between reboots of the AP? Individual TCP/IP sessions? As I said, it might be possible but not practically feasible for various reasons. Plus there's also some, very limited, security in knowing what MAC address your AP and workstations has. That said, MAC address security is an administrative burden for anything but tiny home networks and easy to circumvent.

Reply Parent Score: 2

RE[4]: Comment by clhodapp
by phoenix on Tue 22nd Nov 2011 18:41 in reply to "RE[3]: Comment by clhodapp"
phoenix Member since:
2005-07-11

Soulbender,

"In practice MAC addresses are not unique (and don't actually have to be)."

I really would like to know what you mean here, because in practice having duplicate MAC addresses will break things like DHCP and switching hubs which rely on a MAC address's uniqueness.


MAC addresses have to be unique only within the same broadcast domain (ie, subnet). MAC addresses do not have to be unique on separate subnets, even if within the same building.

Most consumer wireless routers will automatically clone the MAC address of the computer it's connected to, using that MAC address on it's WAN interface. You then have two devices in the same location with the same MAC address. But, they are on separate subnets, in separate broadcast domains, so it all works.

Reply Parent Score: 2