From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 6 Aug 2002 22:51:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 6 Aug 2002 22:51:03 -0400 Received: from pcp01179415pcs.strl1201.mi.comcast.net ([68.60.208.36]:9206 "EHLO mythical") by vger.kernel.org with ESMTP id ; Tue, 6 Aug 2002 22:51:03 -0400 Date: Tue, 6 Aug 2002 22:54:10 -0400 From: Ryan Anderson To: "Richard B. Johnson" Cc: "Randy.Dunlap" , linux-kernel@vger.kernel.org, abraham@2d3d.co.za Subject: Re: ethtool documentation Message-ID: <20020807025410.GG24032@mythical.michonline.com> Mail-Followup-To: "Richard B. Johnson" , "Randy.Dunlap" , linux-kernel@vger.kernel.org, abraham@2d3d.co.za References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > The EEPROM (SEEPROM) on these NICS is used to contain the startup > configuration bits and the IEEE Station Address. This must be a > unique number that is assigned so that there is no other such > number in (preferably) the world, and certainly in the LAN. > If you let a user write to this area, you will allow the user > to destroy the connectivity on a LAN. > > If you provide an ioctl() to write new SEEPROM contents, it had > better be disabled in code that user's (any, including root) > can execute because, if caught, your company may lose it's IEEE > Station Addresses and never again be allowed to configure Ethernet > Controllers. I think you overstate the seriousness here - it's not unheard of for manufacturers to ship hardware with duplicate MAC addresses - a trivial search on Google turns up Cisco as one offender: http://www.cisco.com/warp/public/770/7.html > > Because of this, there is no such thing as 'unused eeprom space' in > the Ethernet Controllers. Be careful about putting this weapon in > the hands of the 'public'. All you need is for one Linux Machine > on a LAN to end up with the same IEEE Station Address as another > on that LAN and connectivity to everything on that segment will > stop. You do this once at an important site and Linux will get a > very black eye. Worse than GE? http://www.gefanuc.com/support/plc/m030202.htm Being able to permanently fix a screwed up card that duplicated another card on my LAN would be nice, imo. Of course, this assumes that IEEE Station Address == MAC address. -- Ryan Anderson sometimes Pug Majere