From owner-freebsd-security Fri Dec 1 12:57: 1 2000 Delivered-To: freebsd-security@freebsd.org Received: from mohegan.mohawk.net (mohegan.mohawk.net [63.66.68.21]) by hub.freebsd.org (Postfix) with ESMTP id 7ACA337B404 for ; Fri, 1 Dec 2000 12:56:58 -0800 (PST) Received: from mohegan.mohawk.net (mohegan.mohawk.net [63.66.68.21]) by mohegan.mohawk.net (8.9.3/8.9.3) with ESMTP id QAA93146; Fri, 1 Dec 2000 16:02:11 -0500 (EST) (envelope-from rjh@mohawk.net) Date: Fri, 1 Dec 2000 16:02:11 -0500 (EST) From: Ralph Huntington To: Brett Glass Cc: Umesh Krishnaswamy , freebsd-security@FreeBSD.ORG, Umesh Krishnaswamy Subject: Re: Defeating SYN flood attacks In-Reply-To: <4.3.2.7.2.20001201131729.04907bf0@localhost> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org This is very very clever. I don't see any holes in it (anyone else?). On Fri, 1 Dec 2000, Brett Glass wrote: > Steve Gibson just published a great article on SYN flood avoidance, > complete with a mechanism that I think FreeBSD should adopt for it. > See > > http://grc.com/r&d/nomoredos.htm > > --Brett > > At 12:04 PM 12/1/2000, Umesh Krishnaswamy wrote: > > >Hi Folks, > > > >I wanted to double-check which version of FreeBSD (if any) can address a > >SYN flooding DoS attack. The latest FreeBSD sources (tcp_input.c and > >ip_input.c) do not seem to have any code to address such an attack. Maybe I am > >missing something. > > > >So if you folks can enlighten me on whether or how to handle the SYN attack from > >within the kernel, I would appreciate it. I am aware of ingress filtering; while > >that can help attacks from randomized IP addresses, it will fail in the case of > >an attack from a spoofed trusted IP address. Hence the desire to look into the > >kernel for a fix. > > > >Thanks. > >Umesh. > > > > > > > > > >To Unsubscribe: send mail to majordomo@FreeBSD.org > >with "unsubscribe freebsd-security" in the body of the message > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-security" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message