From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Flex Subject: Re: synflood +syncookies + conntrack strange behaviour Date: Sat, 11 May 2013 12:47:05 -0600 Message-ID: <518E9229.20504@gmail.com> References: <518C479D.1070904@gmail.com> <518E8D5B.3060200@plouf.fr.eu.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=i/lGh30G/U8gs1HSPbTX5UgEoSUpdXsN/rlz+jFN0Yw=; b=t9sj3ThJVIzUeUvrUDQK0khWsZDqJ8T4cS3iUYNskUyPlWLxn9ZXc2hwem1TjW3u3m oDr2LIYEHVaTXm9xua5PdeWFFZihL+C/JvyZzbz/GDxzYxNcexym4/IbiYqmP9qEuEWm VkUmZqc2PQTBcXJybmZGP/IyiyAPfsj3uD/QzJx12/oY/0j2ImkTYmgsC4lSP80j99TM CDRG4s2bfl0ok23JzW/b0KwhoP3Qbo9sKv/32IY32Wu2fj9IEXJJO4pFdTcoEmnh+zYU u0kZbvvEn8H6Ikr9VluWDS8TbE1Js+VHh3j/5sZx+aTrAze3NInJhCfr3HK7v5l6EmMd bdXA== In-Reply-To: <518E8D5B.3060200@plouf.fr.eu.org> Sender: netfilter-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: netfilter@vger.kernel.org Pascal, Thank you for your reply. Ok, I made sure: a.) conntrack is 100% disabled. b.) iptables is enabled with a simple stateless ruleset. c.) Syn cookies is enabled. The issue is: In my testing Iam still being able to exaust *something* because immediately when i hit a syn flood on port 80 (medium size) I get imediate packet loss (as seen through ICMP, also i cannot ssh in the machine and unable to reach port 80. IF i disable syncookies then: I can ping the machine fine no packetloss but I cannot reach port 80 (seems this port is the only one in packetloss) Question: What resource can be exausted both when syncookies is enabled and disabled for this to happen? Thanks Alex