From owner-freebsd-transport@freebsd.org Wed Jan 17 21:55:41 2018 Return-Path: Delivered-To: freebsd-transport@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B9C5BEBA3AE for ; Wed, 17 Jan 2018 21:55:41 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from drew.franken.de (mail-n.franken.de [193.175.24.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.franken.de", Issuer "COMODO RSA Domain Validation Secure Server CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7F1126DF for ; Wed, 17 Jan 2018 21:55:37 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from [IPv6:2003:cd:6bec:5d00:918e:a13:5702:9225] (p200300CD6BEC5D00918E0A1357029225.dip0.t-ipconnect.de [IPv6:2003:cd:6bec:5d00:918e:a13:5702:9225]) (Authenticated sender: macmic) by mail-n.franken.de (Postfix) with ESMTPSA id 161ED721E282E for ; Wed, 17 Jan 2018 22:55:29 +0100 (CET) From: Michael Tuexen Content-Type: multipart/mixed; boundary="Apple-Mail=_B9794113-F72C-4777-B628-7E55D78DA29C" Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) Subject: TCP Fast Open Linux behaviour Message-Id: <2AE83CF2-FF6D-4849-AEB9-7FCCA43613A9@freebsd.org> Date: Wed, 17 Jan 2018 22:55:24 +0100 To: freebsd-transport@freebsd.org X-Mailer: Apple Mail (2.3445.5.20) X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=disabled version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on mail-n.franken.de X-BeenThere: freebsd-transport@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Discussions of transport level network protocols in FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Jan 2018 21:55:41 -0000 --Apple-Mail=_B9794113-F72C-4777-B628-7E55D78DA29C Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Dear all, at the last Telco the following question was raised: When Linux is acting as TCP client using TCP fast open, does it accept user data sent with the SYN-ACK. I tested it with the Linux kernel 4.9.77, which is the current LTS release and figured out that the data sent with the SYN-ACK is accepted. See the attached .pcapng file. The current Ubuntu 17.10 using the kernel 4.13.0 shows the same behaviour. Best regards Michael --Apple-Mail=_B9794113-F72C-4777-B628-7E55D78DA29C Content-Disposition: attachment; filename=linux.pcapng Content-Type: application/octet-stream; x-unix-mode=0644; name="linux.pcapng" Content-Transfer-Encoding: base64 Cg0NCnAAAABNPCsaAQAAAP//////////AwAQAExpbnV4IDQuOS43Ny12NysEADgARHVtcGNhcCAo V2lyZXNoYXJrKSAyLjIuNiAoR2l0IFJldiBVbmtub3duIGZyb20gdW5rbm93bikAAAAAcAAAAAEA AABMAAAAAQAAAAAABAACAAQAZXRoMAkAAQAJAAAACwAMAAB0Y3AgcG9ydCA4MAwAEABMaW51eCA0 LjkuNzctdjcrAAAAAEwAAAAGAAAAvAAAAAAAAADttQoVEx6aTJkAAACZAAAAuCfrEFtquCfrSMXe CABFAACLoJhAAEAGFZ7AqAF5wKgBba9WAFDFIWIoAAAAANACchCEtAAAAgQFtAQCCAoABcKwAAAA AAEDAwciCv7kfKiRviZLAQFHRVQgL2NnaS1iaW4vaGUgSFRUUC8xLjANClVzZXItYWdlbnQ6IHRj cF9mbw0KQ29ubmVjdGlvbjogY2xvc2UNCg0KAAAAvAAAAAYAAACIAAAAAAAAAO21ChUolIFNZwAA AGcAAAC4J+tIxd64J+sQW2oIAEUAAFkAAEAAQAa2aMCoAW3AqAF5AFCvVjR3Rs/FIWJs0BL//yGb AAACBAW0AQMDBgQCCApiduT0AAXCsCIK/uR8qJG+JksAAEhUVFAvMS4wIDIwMCBPSw0KAIgAAAAG AAAAZAAAAAAAAADttQoVvkeDTUIAAABCAAAAuCfrEFtquCfrSMXeCABFAAA0oJlAAEAGFfTAqAF5 wKgBba9WAFDFIWJsNHdG4YAQAOWEXQAAAQEICgAFwrFiduT0AABkAAAABgAAAHwBAAAAAAAA7bUK FW+aj01cAQAAXAEAALgn60jF3rgn6xBbaggARQABTgAAQABABrVzwKgBbcCoAXkAUK9WNHdG4cUh YmyAGQQCtIkAAAEBCApiduT1AAXCsW9udGVudC10eXBlOiB0ZXh0L2h0bWwNCg0KPCFET0NUWVBF IGh0bWw+CjxodG1sPgo8aGVhZD4KPG1ldGEgY2hhcnNldD0iVVRGLTgiPgo8dGl0bGU+SGFwcHkg RXllYmFsbHM8L3RpdGxlPgo8L2hlYWQ+Cjxib2R5Pgo8cD5UaGlzIHBhZ2Ugd2FzIHJlcXVlc3Rl ZCBmcm9tIDE5Mi4xNjguMS4xMjE6NDQ4ODYgYW5kIHNlcnZlZCBieSBycGkzOjgwIHVzaW5nIFRD UCBhcyB0aGUgdHJhbnNwb3J0IHByb3RvY29sLjwvcD4KPHA+RmFzdCBvcGVuIHdhcyB1c2VkLjwv cD4KPC9ib2R5Pgo8L2h0bWw+CnwBAAAGAAAAZAAAAAAAAADttQoVnnzlTUIAAABCAAAAuCfrEFtq uCfrSMXeCABFAAA0oJpAAEAGFfPAqAF5wKgBba9WAFDFIWJsNHdH/IARAO2EXQAAAQEICgAFwrJi duT1AABkAAAABgAAAGQAAAAAAAAA7bUKFQab8U1CAAAAQgAAALgn60jF3rgn6xBbaggARQAANAAA QABABraNwKgBbcCoAXkAUK9WNHdH/MUhYm2AEAQCkLAAAAEBCApiduT8AAXCsgAAZAAAAA== --Apple-Mail=_B9794113-F72C-4777-B628-7E55D78DA29C--