[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [tor-talk] Mac?
On Thursday, September 08, 2011 7:32 PM, "Seth David Schoen"
> Andre Risling writes:
> > I've some questions about MAC address and changing it
> > - Why would someone want to change ("spoof") their MAC address?
> The MAC address usually identifies a particular physical computer
> to a local area network. If someone doesn't want their physical
> computer to be recognized by a network, they might want to change
> the address.
> The most common reasons for this in practice are probably
> * Some networks let people use the network for free, but only for
> a limited period of time, or only on one occasion; this is
> enforced using MAC addresses, so changing MAC addresses lets
> people get around the restriction and continue using the
> network. For example, an airport or university wifi network
> might let a "guest" use the network for 30 minutes without
> paying or registering.
> * Some networks might ban someone they consider abusive or
> unwelcome using the MAC address (for example, an open wifi
> network where someone has used it in a way that the operator
> considered abusive or excessive). In that case, the person
> who was banned might change their MAC address to get around
> the ban.
> * ISPs might record or log MAC addresses, which could be used for
> commercial or law enforcement purposes, so someone who doesn't
> want to end up in such logs might use a false or random MAC
> address. In some places, law enforcement might pressure or
> require the ISPs to keep these logs as a way of trying to catch
> people accused of breaking the law, or as a way of providing
> corroborating evidence after-the-fact when a suspect is caught.
> * Although it's not known to happen on a large scale, other people
> on a LAN with you could detect and log your MAC address to
> monitor when your computer is physically present on the LAN
> (perhaps to learn or make a profile of when you're present at
> a certain place that you're known to visit periodically?), so
> changing your MAC address would let you avoid this kind of
> * Some ISPs use a clumsy policy where the subscriber's observed
> MAC address is not allowed to change frequently (sometimes
> because of somewhat obsolete ISP billing systems that used the
> MAC address to identify the subscriber, or sometimes because
> of old ISP policies meant to discourage people from using more
> than one computer with a single account). In this case,
> people may change the MAC address of one computer (or a wifi
> router) to match the address of a different computer (which
> is called "cloning"). This could also be used by someone
> who has paid for a certain amount of Internet access on a paid
> wifi network (say, in an airport or hotel) let a friend take
> over using the access when the first person is all done.
> > - Is a computers MAC address sent out whenever you connect to the web?
> > -If it is, how often is it sent out?
> It's "sent out" to the local router but not out over the Internet,
> so web servers, for example, can't observe it. You have to be on
> the same LAN in order to observe it.
> > - Who stores the MAC address of the computer you're using? The ISP? An
> > Webmail service?
> Whoever operates the local router can store it (e.g., if you're on a
> friend's wifi, the friend could store it; if you're on a commercial
> wifi network, the commercial wifi operator could store it; if you're
> directly plugged into a cable modem owned by an ISP, the ISP could
> program the cable modem to store it; ...).
> An exception is that some software could deliberately choose to
> transmit the MAC address for its own reasons, like enforcing
> anti-copying restrictions or because of a weird choice to use the
> MAC address to identify individual computers for some other reason.
> There's nothing about how the Internet works that _requires_ any
> software to do this, and it's probably not common.
> > -Does the Tor network capture and store Mac addresses?
> Nope, never.
> Seth Schoen <schoen@xxxxxxx>
> Senior Staff Technologist https://www.eff.org/
> Electronic Frontier Foundation https://www.eff.org/join
> 454 Shotwell Street, San Francisco, CA 94110 +1 415 436 9333 x107
> tor-talk mailing list
Excellent! Thank you for the thorough answers.
http://www.fastmail.fm - The way an email service should be
tor-talk mailing list