From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86965C7619A for ; Tue, 11 Apr 2023 10:25:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229782AbjDKKZm (ORCPT ); Tue, 11 Apr 2023 06:25:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229783AbjDKKZh (ORCPT ); Tue, 11 Apr 2023 06:25:37 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3053A9 for ; Tue, 11 Apr 2023 03:25:35 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1pmBBs-0000nM-75; Tue, 11 Apr 2023 12:25:32 +0200 Date: Tue, 11 Apr 2023 12:25:32 +0200 From: Florian Westphal To: Pablo Neira Ayuso Cc: Florian Westphal , Jeremy Sowden , Netfilter Devel Subject: Re: [PATCH nftables 8/8] test: py: add tests for shifted nat port-ranges Message-ID: <20230411102532.GC21051@breakpoint.cc> References: <20230305101418.2233910-1-jeremy@azazel.net> <20230305101418.2233910-9-jeremy@azazel.net> <20230324225904.GB17250@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Pablo Neira Ayuso wrote: > On Fri, Mar 24, 2023 at 11:59:04PM +0100, Florian Westphal wrote: > > Jeremy Sowden wrote: > > > +ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to 192.168.127.1:5900-5910/55900;ok > > > +ip6 daddr 10::1 tcp dport 55900-55910 dnat ip6 to [::c0:a8:7f:1]:5900-5910/55900;ok > > > > This syntax is horrible (yes, I know, xtables fault). > > > > Do you think this series could be changed to grab the offset register from the > > left edge of the range rather than requiring the user to specify it a > > second time? Something like: > > > > ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to 192.168.127.1:5900-5910 > > > > I'm open to other suggestions of course. > > To allow to mix this with maps, I think the best approach is to add a > new flag (port-shift) and then allow the user to specify the > port-shift 'delta'. > > ip daddr 10.0.0.1 tcp dport 55900-55910 dnat ip to ip saddr map { \ > 192.168.127.0-129.168.127.128 : 1.2.3.4 . -55000 } port-shift Sorry, I don't see the usecase for different deltas. But even if we assume that, kernel already takes the dnat target port number from a register. > where -55000 means, subtract -55000 to the tcp dport in the packet, it > is an incremental update. > > This requires a kernel patch to add the new port-shift flag. ... so I don't see why we need a new port-shift flag at all. I think best approach is to provide the actual new dport in a register, like we already do right now. So we need an 'add' operation in kernel to compute portreg = sreg_with_port + sreg_with_offset > > Florian, this is based on your idea to support 'add' command, which is > still needed for other usecases. I think nat is special in the sense > that the goal is to feed the registers that instruct the NAT engine > what kind of mangling is needed. See above. I don't think we should go with the existing NAT flag, its very much a hack to overcome iptables design limitations.