Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933916AbbGHIDx (ORCPT ); Wed, 8 Jul 2015 04:03:53 -0400 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:54717 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934761AbbGHICE (ORCPT ); Wed, 8 Jul 2015 04:02:04 -0400 X-Sasl-enc: atx/dZrL+42cW2Q9ZR6tbYVwYQ0DJxgsmJs8amNX8nYt 1436342523 Message-ID: <1436342521.2928.4.camel@stressinduktion.org> Subject: Re: [PATCH v2] add stealth mode From: Hannes Frederic Sowa To: Matteo Croce Cc: Valdis Kletnieks , Nicolas Dichtel , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 08 Jul 2015 10:02:01 +0200 In-Reply-To: References: <21611.1436179798@turing-police.cc.vt.edu> <1436256473.3809610.317083993.4E2A41A3@webmail.messagingengine.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.3 (3.16.3-2.fc22) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1988 Lines: 55 On Tue, 2015-07-07 at 17:27 +0200, Matteo Croce wrote: > 2015-07-07 10:07 GMT+02:00 Hannes Frederic Sowa < > hannes@stressinduktion.org>: > > > > > > On Mon, Jul 6, 2015, at 21:44, Matteo Croce wrote: > > > 2015-07-06 12:49 GMT+02:00 : > > > > On Thu, 02 Jul 2015 10:56:01 +0200, Matteo Croce said: > > > > > Add option to disable any reply not related to a listening > > > > > socket, > > > > > like RST/ACK for TCP and ICMP Port-Unreachable for UDP. > > > > > Also disables ICMP replies to echo request and timestamp. > > > > > The stealth mode can be enabled selectively for a single > > > > > interface. > > > > > > > > A few notes..... > > > > > > > > 1) Do you have an actual use case where an iptables '-j DROP' > > > > isn't usable? > > > > > > If you mean using a default DROP policy and allowing only the > > > traffic > > > do you want, > > > then the use case is where the port can change at runtime and you > > > may not > > > want > > > to update the firewall every time > > > > Can't you use socket match in netfilter to accomplish exactly that? > > You mean the owner --uid match? > Yes sort of, but my was a different goal, I want just to disable any > kind of reply from a specific interface (usually WAN) unless there is > a listening socket, to mitigate port scanning and flood attacks > without having a firewall. I was more thinking about the xt_socket match: -m socket in the INPUT chain. > Obviously you can do it with a firewall, > but why do we have /proc/sys/net/ipv4/icmp_echo_ignore_all when we can > drop ICMP echoes? Same arguments apply to that knob, but it is already imported and cannot be changed anymore. Nowadays we try to avoid adding new sysctls. Bye, Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/