From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753774AbaHSTgr (ORCPT ); Tue, 19 Aug 2014 15:36:47 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:37975 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751918AbaHSTgp (ORCPT ); Tue, 19 Aug 2014 15:36:45 -0400 Message-ID: <53F3A739.4070203@ahsoftware.de> Date: Tue, 19 Aug 2014 21:36:25 +0200 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Eric Dumazet , Christian Grothoff CC: Jacob Appelbaum , Andi Kleen , Stephen Hemminger , David Miller , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, knock@gnunet.org Subject: Re: [PATCH] TCP: add option for silent port knocking with integrity protection References: <52A75EF8.3010308@in.tum.de> <20131211.150137.368953964178408437.davem@davemloft.net> <52A8C8B4.4060109@in.tum.de> <20131211122637.75b09074@nehalam.linuxnetplumber.net> <87bo0nulkt.fsf@tassilo.jf.intel.com> <52A8ECF5.3070604@in.tum.de> <20131212012317.GL21717@two.firstfloor.org> <52A98DBF.4090702@appelbaum.net> <52A9A17F.6050505@in.tum.de> <1386858864.19078.60.camel@edumazet-glaptop2.roam.corp.google.com> In-Reply-To: <1386858864.19078.60.camel@edumazet-glaptop2.roam.corp.google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 12.12.2013 15:34, schrieb Eric Dumazet: A bit late, but I've just stumbled over that feature which I do like a lot. > Very soon you'll need to support different secrets. You do not want all > clients share a common secret, do you ? How can a server change its > secret without disrupting clients ? Impossible because you already need a channel if you want to identify the client. But that isn't the intention of the patch. You still have the usual authentication stuff in the service you want to hide. It's about hiding (from someone outside a closed group) the possibility to authenticate. > How having a constant initial sequence number can even be valid ? > What about TCP timestamps being not available at all ? > How typical servers can be behind a load balancer ? > Or am I missing something ? It doesn't have to work in every environment and it doesn't have to solve all existing problems in the world. ;) But it enables people to protect a bit more against malicious people or governments. And it is really very easy to use. It took me around half an hour to find the places in openvpn and openssh where I had to add the setsockopt() call and it can be used even easier with preloading libknockify.so. There can be found much more useless options in the kernel. At least I like it and it fits my needs too. Regards, Alexander Holler