Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757572AbZIOABj (ORCPT ); Mon, 14 Sep 2009 20:01:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757549AbZIOABh (ORCPT ); Mon, 14 Sep 2009 20:01:37 -0400 Received: from ja.ssi.bg ([217.79.71.194]:60078 "EHLO u.domain.uli" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755394AbZIOABg (ORCPT ); Mon, 14 Sep 2009 20:01:36 -0400 Date: Tue, 15 Sep 2009 03:01:47 +0300 (EEST) From: Julian Anastasov X-X-Sender: ja@u.domain.uli To: Stephen Hemminger cc: Stephan von Krawczynski , Eric Dumazet , linux-kernel@vger.kernel.org, davem@davemloft.net, Linux Netdev List Subject: Re: ipv4 regression in 2.6.31 ? In-Reply-To: <20090914093128.4d709ff6@nehalam> Message-ID: References: <20090914150935.cc895a3c.skraw@ithnet.com> <4AAE4BAF.2010406@gmail.com> <20090914175505.a3f132ee.skraw@ithnet.com> <20090914093128.4d709ff6@nehalam> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1569 Lines: 39 Hello, On Mon, 14 Sep 2009, Stephen Hemminger wrote: > RP filter did not work correctly in 2.6.30. The code added to to the loose > mode caused a bug; the rp_filter value was being computed as: > rp_filter = interface_value & all_value; > So in order to get reverse path filter both would have to be set. May be we can add IN_DEV_MASKCONF as a better option (all & dev). All loose-mode fans just need to set all/rp_filter to 3 to allow both strict and loose mode and then DEV/rp_filter will be restricted to the allowed modes. By this way compatibility is preserved (all/rp_filter will mean "allowed modes") and you can add other loose-mode variants as explained in RFC 3704. Then strict mode will have priority to all loose modes when checking the sender address. Or if we really want to help asymmetric routing we should not play with loose modes but with solutions like rp_filter_mask: http://www.ssi.bg/~ja/#rp_filter_mask where we can use the DEV/medium_id knowledge for rp_filter, not just for proxy_arp. The drawback is that currently it is limited to 31 mediums. Still, it serves the main goal of RFC 3704: 2.3. Feasible Path Reverse Path Forwarding. Then users can use loose mode to fight against martians or rp_filter_mask for setups with asymmetric routing. Regards -- Julian Anastasov -- 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/