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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAD59C433E0 for ; Tue, 30 Jun 2020 20:44:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FC1720772 for ; Tue, 30 Jun 2020 20:44:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729927AbgF3Uob (ORCPT ); Tue, 30 Jun 2020 16:44:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728340AbgF3Uoa (ORCPT ); Tue, 30 Jun 2020 16:44:30 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A299FC061755; Tue, 30 Jun 2020 13:44:30 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 30C731277FAD7; Tue, 30 Jun 2020 13:44:30 -0700 (PDT) Date: Tue, 30 Jun 2020 13:44:29 -0700 (PDT) Message-Id: <20200630.134429.1590957032456466647.davem@davemloft.net> To: edumazet@google.com Cc: mathieu.desnoyers@efficios.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ycheng@google.com, joraj@efficios.com Subject: Re: [regression] TCP_MD5SIG on established sockets From: David Miller In-Reply-To: References: <312079189.17903.1593549293094.JavaMail.zimbra@efficios.com> X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 30 Jun 2020 13:44:30 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet Date: Tue, 30 Jun 2020 13:39:27 -0700 > The (C) & (B) case are certainly doable. > > A) case is more complex, I have no idea of breakages of various TCP > stacks if a flow got SACK > at some point (in 3WHS) but suddenly becomes Reno. I agree that C and B are the easiest to implement without having to add complicated code to handle various negotiated TCP option scenerios. It does seem to be that some entities do A, or did I misread your behavioral analysis of various implementations Mathieu? Thanks.