From owner-freebsd-security@FreeBSD.ORG Sun Oct 26 23:31:51 2003 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0AC9516A4B3 for ; Sun, 26 Oct 2003 23:31:51 -0800 (PST) Received: from lariat.org (lariat.org [63.229.157.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 41B2A43F75 for ; Sun, 26 Oct 2003 23:31:50 -0800 (PST) (envelope-from brett@lariat.org) Received: (from brett@localhost) by lariat.org (8.9.3/8.9.3) id AAA23485 for security@freebsd.org; Mon, 27 Oct 2003 00:31:46 -0700 (MST) Date: Mon, 27 Oct 2003 00:31:46 -0700 (MST) From: Brett Glass Message-Id: <200310270731.AAA23485@lariat.org> To: security@freebsd.org Subject: Best way to filter "Nachi pings"? X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Security issues [members-only posting] List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Oct 2003 07:31:51 -0000 We're being ping-flooded by the Nachi worm, which probes subnets for systems to attack by sending 92-byte ping packets. Unfortunately, IPFW doesn't seem to have the ability to filter packets by length. Assuming that I stick with IPFW, what's the best way to stem the tide? --Brett Glass