From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: "Mark RISON" To: bluez-devel@lists.sourceforge.net Subject: Re: [Bluez-devel] bd_addr question Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: Sender: bluez-devel-admin@lists.sourceforge.net Errors-To: bluez-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 10 Mar 2004 16:04:32 +0000 Steven Singer : >Michael Schmidt wrote: > > Keep in mind that you break some of the BT functionality when you use > > variable BD_ADDRs: The pairing-based security mechanisms (authentication > > and encryption) rely on a constant BD_ADDR. I guess there is more > > functionality that is affected by the change. >Don't forget that Bluetooth addresses must be unique otherwise unpleasant >things happen. >Bluetooth addresses come out of the same address space as MAC addresses, >if you want to use your own then you need to get an OUI or IAB allocation >from the IEEE. Well, you could use a MAC address with the U(niversal)/L(ocal) bit set, which would correspond to a BD_ADDR with bit 9 of the NAP set, as long as you can guarantee its uniqueness (which in practice means you have control of all the devices which might participate in your network; bear in mind that some MAC addresses were allocated with that bit set in pre-IEEE days). You don't have to buy/register locally-administered MAC addresses. >The BD ADDR <-> MAC point is important. If you start running BNEP >(Bluetooth Network Encapsulation Protocol = Ethernet over Bluetooth) >then the Bluetooth device will use its Bluetooth address as its Ethernet >MAC address. This means that you can't simply take the MAC address from >another device on your system (say an Ethernet card) and use it as your >Bluetooth address. Unless you refrain from using that Ethernet card in the same network as your Bluetooth device. (This is/was the basis of a popular way to buy a few MAC addresses: buy a few bargain-basement NICs, read their BD_ADDRs, and junk the NICs). Another top tip: don't pick addresses with the I(ndividual)/G(roup) bit set (i.e. multicast addresses), which would correspond to a BD_ADDR with bit 8 of the NAP set. BNEP devices are almost certain to get very confused by this! Mark -- CPC/IP - A TCP/IP stack for Amstrad CPCs -- http://www.nenie.org/cpcip/ "Z88 vs CPC? Christ. How did we miss that platform war?" -- http://www.ntk.net/index.cgi?back=archive00/now0128.txt&line=110#l _________________________________________________________________ Create a Job Alert on MSN Careers and enter for a chance to win $1000! http://msn.careerbuilder.com/promo/kaday.htm?siteid=CBMSN_1K&sc_extcmp=JS_JASweep_MSNHotm2 ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ Bluez-devel mailing list Bluez-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bluez-devel