From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: vnet problem (bug? feature?) Date: Mon, 16 Feb 2015 08:30:12 -0700 Message-ID: <54E20D04.8050409@gmail.com> References: <20150213114113.GA10559@faui40p.informatik.uni-erlangen.de> <20150214101547.GA9335@faui40p.informatik.uni-erlangen.de> <20150214131744.051b90fc8dfdbf4e1bfe6bfb@mindspring.com> <20150215190008.GA25792@faui40p.informatik.uni-erlangen.de> <20150216101309.GB25792@faui40p.informatik.uni-erlangen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Bill Fink , Cong Wang , netdev To: Toerless Eckert , Sowmini Varadhan Return-path: Received: from mail-ie0-f176.google.com ([209.85.223.176]:45639 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199AbbBPPaU (ORCPT ); Mon, 16 Feb 2015 10:30:20 -0500 Received: by iecat20 with SMTP id at20so34584255iec.12 for ; Mon, 16 Feb 2015 07:30:19 -0800 (PST) In-Reply-To: <20150216101309.GB25792@faui40p.informatik.uni-erlangen.de> Sender: netdev-owner@vger.kernel.org List-ID: On 2/16/15 3:13 AM, Toerless Eckert wrote: > I fail to find a good reference explaining why linux would default to > rp_filtering = 1 (more appropriate for routers) even if forwarding defaults to 0 > (more appropriate for multi-homed hosts). It's a userspace default. For Fedora/Red Hat based systems see /etc/sysctl.conf (older releases) and /usr/lib/sysctl.d/50-default.conf (newer ones). I recall it defaulting to 1 in the early 2000's so it has been that way for a long time. From Documentation/networking/ip-sysctl.txt: rp_filter - INTEGER ... Default value is 0. Note that some distributions enable it in startup scripts. David