From owner-freebsd-net Wed Jan 24 10:37:50 2001 Delivered-To: freebsd-net@freebsd.org Received: from ebola.biohz.net (ebola.biohz.net [206.80.1.35]) by hub.freebsd.org (Postfix) with ESMTP id C419E37B400 for ; Wed, 24 Jan 2001 10:37:32 -0800 (PST) Received: from flu (localhost [127.0.0.1]) by ebola.biohz.net (Postfix) with SMTP id 2B6063A282; Wed, 24 Jan 2001 10:37:32 -0800 (PST) Message-ID: <000d01c08634$b6702c80$0402010a@biohz.net> From: "Renaud Waldura" To: "C. Stephen Gunn" Cc: References: <006901c085ae$fae9bd80$0402010a@biohz.net> <20010124003305.B231@waterspout.com> Subject: Re: How to send arp request with no other traffic Date: Wed, 24 Jan 2001 10:37:31 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > You can't really assume this will work. FreeBSD has a sysctl > to disable responses to broadcast/multicast ICMP-echo requests. You know what, I tried it with Windows machines, that do not reply to broadcast ping either, and it worked anyway. What gives? ----- Original Message ----- From: "C. Stephen Gunn" To: "Renaud Waldura" Cc: "Patrick Bihan-Faou" ; Sent: Tuesday, January 23, 2001 9:33 PM Subject: Re: How to send arp request with no other traffic > > On Tue, Jan 23, 2001 at 06:40:14PM -0800, Renaud Waldura wrote: > > > An amusing trick to populate the ARP table is to ping the broadcast address. > > Even if hosts do not reply to your ping packet (typically, Windows > > machines), they are entered in the ARP table. > > > > You still have to send a single packet, but it does all the work. > > You can't really assume this will work. FreeBSD has a sysctl > to disable responses to broadcast/multicast ICMP-echo requests. > > Exploitation of this "feature" is the basis for several denial > of service attacks. Spoof the origin address to an layer-3 > broadcast address and voila, amplified responses. :-( > > - Steve > > -- > C. Stephen Gunn | Waterspout Communications, Inc. > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message