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 B095FC7619A for ; Tue, 11 Apr 2023 08:29:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230431AbjDKI3H (ORCPT ); Tue, 11 Apr 2023 04:29:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230238AbjDKI2z (ORCPT ); Tue, 11 Apr 2023 04:28:55 -0400 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4B7AE4210 for ; Tue, 11 Apr 2023 01:28:29 -0700 (PDT) Date: Tue, 11 Apr 2023 10:28:17 +0200 From: Pablo Neira Ayuso To: Florian Westphal Cc: Jeremy Sowden , Netfilter Devel Subject: Re: [PATCH nftables 8/8] test: py: add tests for shifted nat port-ranges Message-ID: 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=utf-8 Content-Disposition: inline In-Reply-To: <20230324225904.GB17250@breakpoint.cc> Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi, 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 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. It should be possible to add a new netlink attribute NFTA_NAT_REG_PROTO_SHIFT which allows for -2^16 .. +2^16 to express the (positive/negative) delta offset. Parser would need to be taught to deal with negative and positive offset, we probably need a new special type for named maps too (port-shift). 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.