From owner-freebsd-security Sun Dec 10 21: 8: 0 2000 From owner-freebsd-security@FreeBSD.ORG Sun Dec 10 21:07:57 2000 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mailhost01.reflexnet.net (mailhost01.reflexnet.net [64.6.192.82]) by hub.freebsd.org (Postfix) with ESMTP id B3CA937B400 for ; Sun, 10 Dec 2000 21:07:57 -0800 (PST) Received: from 149.211.6.64.reflexcom.com ([64.6.211.149]) by mailhost01.reflexnet.net with Microsoft SMTPSVC(5.5.1877.197.19); Sun, 10 Dec 2000 21:06:18 -0800 Received: (from cjc@localhost) by 149.211.6.64.reflexcom.com (8.11.0/8.11.0) id eBB57lm18707; Sun, 10 Dec 2000 21:07:47 -0800 (PST) (envelope-from cjc) Date: Sun, 10 Dec 2000 21:07:47 -0800 From: "Crist J. Clark" To: Mikhail Kruk Cc: Daniel Hauer , freebsd-security@FreeBSD.ORG Subject: Re: MAC Address Message-ID: <20001210210747.R96105@149.211.6.64.reflexcom.com> Reply-To: cjclark@alum.mit.edu References: <3A3457AA.7507D386@enter.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: ; from meshko@cs.brandeis.edu on Sun, Dec 10, 2000 at 11:34:16PM -0500 Sender: cjc@149.211.6.64.reflexcom.com Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Sun, Dec 10, 2000 at 11:34:16PM -0500, Mikhail Kruk wrote: > > Mikhail Kruk wrote: > > > > > > I'd want to do it because at our university there are plugs for laptops on > > > DHCP network, but DHCP server knows everyone's MAC address so all my > > > activity is logged when I use it. Changing my MAC address would open some > > > interesting posiblities. > > > >From a purely theoretical point of view, of course. > > > > > > > Dave, > > > > > > Sounds to me all this is just_slightly_unethical_if > > _not_bordering_on_illegal. This is a topic for a security mailing list? > > I thought we were here to boost network security, not circumvent it. > > Just a network technician's opinion. > > I said "purely theoretical" and I meant it. > However I'm seriously confused now. Is it really possible to change MAC > address from software as people say here? Of course. A Ethernet frame is just some bits sent out on a wire. If you can write raw frames to the wire, you can use whatever MAC address you want. And think about it, how would bridging work if you couldn't do this? > Isn't the whole point of MAC > address just the oposite? The whole point of hardware MAC addresses is that there is a unique address always available. It might not be used. Note that different systems do this in different ways. PC hardware needs a MAC on the card since there is no dependable unique value on other parts of the system (and for some reason people resist that coming about, remeber the PIII). Other hardware may work differently. For example, on a Sun machine, the unique machine ID is used to generate the MAC. All interfaces on a Sun box will have the same MAC in a default setup. -- Crist J. Clark cjclark@alum.mit.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message