Date: Thu, 19 Feb 1998 22:13:51 -0500 From: Norman C Rice <nrice@emu.sourcee.com> To: Doug White <dwhite@resnet.uoregon.edu> Cc: Nadav Eiron <nadav@barcode.co.il>, jgrosch@superior.mooseriver.com, questions@FreeBSD.ORG Subject: Re: hostid equals Ethernet address or IP address ? Message-ID: <19980219221351.19717@emu.sourcee.com> In-Reply-To: <Pine.BSF.3.96.980219153649.658R-100000@gdi.uoregon.edu>; from Doug White on Thu, Feb 19, 1998 at 03:38:01PM -0800 References: <19980219095703.59598@emu.sourcee.com> <Pine.BSF.3.96.980219153649.658R-100000@gdi.uoregon.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Feb 19, 1998 at 03:38:01PM -0800, Doug White wrote: > On Thu, 19 Feb 1998, Norman C Rice wrote: > > > I find it hard to believe that NIC manufacturers would allow end users > > to freely change the MACs, especially the OUI portion. There would be no > > guarantee of uniqueness and I am sure that a new sport, ``MAC spoofing'', > > would soon be taken up by the crackers. > > There are cases where two NICs on the same net had the same MAC. Allowing > reprogramming saves the company from having to swap NICs. > > This is esp. true on large extended LANs that use bridges rather than > routers. It may not be much of an issue today tho since bridges aren't in > wide a use as they once were. > > Doug White | University of Oregon > Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant > http://gladstone.uoregon.edu/~dwhite | Computer Science Major > Yes, bridges often have the same MAC address on each leg. The problem with duplicate MAC addresses on the same LAN, regardless of its size, is how to resolve the ``arp who has'' requests. Great efforts (software and research) has been expended in an attempt to ensure that MAC addresses are not duplicated except for special cases such as a bridge. I am closely tied to this effort and it's somewhat astonishing to learn that the same people who hound me to ensure the uniqueness of MAC addresses, have me sign NDAs, etc., would provide the ability to reprogram the MAC address to an end user, especially the OUI which sort of negates the accuracy and purpose of the IEEE assignments. Live and learn. :-) -- Regards, Norman C. Rice, Jr. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19980219221351.19717>