From owner-freebsd-questions@FreeBSD.ORG Wed Jan 10 18:12:25 2007 Return-Path: X-Original-To: questions@freebsd.org Delivered-To: freebsd-questions@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 1446216A407 for ; Wed, 10 Jan 2007 18:12:25 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from smtpout.mac.com (smtpout.mac.com [17.250.248.185]) by mx1.freebsd.org (Postfix) with ESMTP id 007DC13C43E for ; Wed, 10 Jan 2007 18:12:24 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from mac.com (smtpin05-en2 [10.13.10.150]) by smtpout.mac.com (Xserve/8.12.11/smtpout15/MantshX 4.0) with ESMTP id l0AHpIRJ026511; Wed, 10 Jan 2007 09:51:19 -0800 (PST) Received: from [17.214.13.96] (a17-214-13-96.apple.com [17.214.13.96]) (authenticated bits=0) by mac.com (Xserve/smtpin05/MantshX 4.0) with ESMTP id l0AHpFSP028793; Wed, 10 Jan 2007 09:51:16 -0800 (PST) In-Reply-To: <45A4FDDA.8040909@skoberne.net> References: <45A4FDDA.8040909@skoberne.net> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed Message-Id: <528B65CB-C5C5-42E7-9380-6EFA83339268@mac.com> Content-Transfer-Encoding: quoted-printable From: Chuck Swiger Date: Wed, 10 Jan 2007 09:51:14 -0800 To: =?WINDOWS-1252?Q?Nejc_=8Akoberne?= X-Mailer: Apple Mail (2.752.2) X-Brightmail-Tracker: AAAAAA== X-Brightmail-scanned: yes Cc: questions@freebsd.org Subject: Re: Simple DoS X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Jan 2007 18:12:25 -0000 On Jan 10, 2007, at 6:53 AM, Nejc =8Akoberne wrote: > yesterday one of our clients did something interesting (stupid): they > connected both ends of an UTP cable to the same switch, to which our > FreeBSD server was also connected. [ ... ] > Any ideas how to prevent such situations in the future? (I would like > to do it on the server side, not on the "user side".) This isn't a FreeBSD-specific issue, but a matter of controlling =20 access to the central networking hardware to only those qualified to =20 deal with it. However, if you purchase higher-quality smart =20 switches, they implement the spanning tree protocol to detect and =20 break loops like the one you've described. --=20 -Chuck