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 lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3D4C6C433F5 for ; Mon, 10 Jan 2022 20:40:09 +0000 (UTC) Received: by lists.zx2c4.com (OpenSMTPD) with ESMTP id 2bc5bc44; Mon, 10 Jan 2022 20:37:40 +0000 (UTC) Received: from mail-ed1-x536.google.com (mail-ed1-x536.google.com [2a00:1450:4864:20::536]) by lists.zx2c4.com (OpenSMTPD) with ESMTPS id f4694c13 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO) for ; Mon, 10 Jan 2022 20:37:37 +0000 (UTC) Received: by mail-ed1-x536.google.com with SMTP id u25so58593198edf.1 for ; Mon, 10 Jan 2022 12:37:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:message-id:date:mime-version:user-agent:content-language:to :from:subject:content-transfer-encoding; bh=2gjGsbVg8LEi2n1eiMHKtm79XeHbaEhsOEofnECR3+8=; b=jvN5v/gae31UN2+qlN9kQoC1HqzUmGNAOFjqT2hlUvcL9wWWvoOuC72FdO2T46QpIn gG9k8y3Pn1P3r7iIqbZ8pPuWf9kGwFabzF2pyc8sgVLwNgTcw9Eq2oWhBekem3tTp3EO Vlxg9anScrmKkg46+qeCqCE5FOutcYQ0j56F70YMUb1TaMBOkgPJH+dogTWZFyI7lVL8 rcomCJCRaO5BtIXE2cgWohWU4L72eHNRVSGpcj+OXbVoQozcokxekEMTmIKJUAoSVnTh uQBFi6k2b/r1HEDwXMdkzV3tzBPFCWK/Njzb3dFLHHUgX2O5yio+onk+BDwGYRttQdTY pDoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:message-id:date:mime-version:user-agent :content-language:to:from:subject:content-transfer-encoding; bh=2gjGsbVg8LEi2n1eiMHKtm79XeHbaEhsOEofnECR3+8=; b=nIxlbEXYySUzEOO2q4vUZVLWe42YqGV7Qqjpc52giwcZzS2tpFhMIL/Jfktamxq8l9 KvQqAtFKJ374hXYdLd6W+aJolq/UfEFWiqax/hi2DrcbUKlOhY7vubpQRCDoI0ysP2AW iK3F53JKmj5uV+oMSm7Uy5wV2Zif+SqtS244DSDrvaSKcXcU0b70O7D535fhKj6bC67/ EK4gl2/sb6aUWvN0Vqz9f+lvaXZ79VMusufXwDNdmBMXWoY5J71Aua0mqLNgfPYzEgoB 2G6vgzFDIjdV3w4V9yOugUY3QW33adRF5Bbpq5jJNb9MsZ/pkxzgCvDHbDSQqJzLLsmd v5CQ== X-Gm-Message-State: AOAM5329tyaPH7MxjcSWLpval16ZDnLbjoTTatgRtdQ0/sLz2MxDuDXW lYf5kBzXiIYq+glbHqlW9EJ1Libp1bs= X-Google-Smtp-Source: ABdhPJy/hLV2MMwOq0ojFGSC1zw1iStHctiNGCXH407YFYse/oaYtV/Uh0zHWDl3X7+EU27Uy1fxdg== X-Received: by 2002:a17:906:4fc7:: with SMTP id i7mr1090500ejw.652.1641847057086; Mon, 10 Jan 2022 12:37:37 -0800 (PST) Received: from mail.otpe.de (otpe.de. [194.163.141.229]) by smtp.gmail.com with ESMTPSA id eg22sm3941456edb.34.2022.01.10.12.37.36 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jan 2022 12:37:36 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 94F0C46002F for ; Mon, 10 Jan 2022 21:37:35 +0100 (CET) Message-ID: <1e345f21-4564-7df8-1aae-32ba14d42779@qupfer.de> Date: Mon, 10 Jan 2022 21:37:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.1 Content-Language: en-US To: wireguard@lists.zx2c4.com From: henning.reich@gmail.com Subject: Question about MTU and Wireguard and the current changes Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" Hi, I run in some connection troubles between two wireguards host (one running fedora 35, one arch linux). If I tried to transfer large files through SSH (SCP or btrfs send/receive thorugh ssh through wireguard tunnel) it stucks after a few byte and nothing transfered anymore. This happens in the last days, so probably an update on one or both machines. I also saw, that there some changes on the MTU thing (If I remember correctly, a per peer MTU is configurable) However. My first try was just set the MTU to a lower number (MTU = 1200) and yes, scp works again. Okay, so I did the good old ping test. "ping -M do -s $SIZE -c 1 172.16.0.2" with $SIZE increasing. And that surprised me. It works until an Size of 36932 Bytes. Checked with wireguard and "MTU = 36932" and yes, scp still working. Can somebody explain, why the old default setting of "65456" doesn't work anymore but the MTU can set to much higher values as typical ones? Thanks Henning