From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v4] add stealth mode Date: Wed, 23 Sep 2015 10:29:52 -0700 Message-ID: <1443029392.29850.119.camel@edumazet-glaptop2.roam.corp.google.com> References: <20150915.120057.1457031142615117336.davem@davemloft.net> <1442397259-28894-1-git-send-email-matteo@openwrt.org> <20150916110629.GP24810@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Florian Westphal , David Miller , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Matteo Croce Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 2015-09-23 at 18:36 +0200, Matteo Croce wrote: > 2015-09-16 13:06 GMT+02:00 Florian Westphal : > > > > Matteo Croce wrote: > > > 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. > > > > I think it would make more sense to extend the socket match > > in xtables if it can't be used to achive this already. > > > > seems like > > *filter > > :INPUT ACCEPT [0:0] > > -A INPUT -p tcp -m socket --nowildcard -j ACCEPT > > -A INPUT -p tcp -j DROP > > COMMIT > > > > Already does what you want for tcp, udp should work too. > > I'd much rather see xtables and/or nftables to be extended > > with whatever feature(s) are needed to configure such a policy > > rather than pushing this into the core network stack. > > The point is to do the filtering without *tables at all, > like /proc/sys/net/ipv4/icmp_echo_ignore_all does for pings Yes, but this adds code in many places, even for people not caring of such protection. The point is : people wanting firewall like protections should instead use netfilter framework.