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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 86FDBC433E0 for ; Thu, 21 Jan 2021 22:09:42 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 133C6221E5 for ; Thu, 21 Jan 2021 22:09:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 133C6221E5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=romanrm.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=wireguard-bounces@lists.zx2c4.com Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id df74c432; Thu, 21 Jan 2021 22:09:38 +0000 (UTC) Received: from rin.romanrm.net (rin.romanrm.net [51.158.148.128]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id 486e0d4b (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO) for ; Thu, 21 Jan 2021 22:09:36 +0000 (UTC) Received: from natsu (unknown [IPv6:fd39::e99e:8f1b:cfc9:ccb8]) by rin.romanrm.net (Postfix) with SMTP id 9DAE539F; Thu, 21 Jan 2021 22:09:35 +0000 (UTC) Date: Fri, 22 Jan 2021 03:09:35 +0500 From: Roman Mamedov To: Harald Dunkel Cc: wireguard@lists.zx2c4.com Subject: Re: mtu on Linux vs MacOS Message-ID: <20210122030935.3f8bba00@natsu> In-Reply-To: <20210121190718.13465dea@natsu> References: <20210121190718.13465dea@natsu> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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" On Thu, 21 Jan 2021 19:07:18 +0500 Roman Mamedov wrote: > On Sun, 17 Jan 2021 11:36:42 +0100 > Harald Dunkel wrote: > > > Hi folks, > > > > I am using PPPoE to connect to my IP provider. To use wireguard on Linux I > > have to reduce the MTU in wg0.conf to 1400. Using the default 1420 a ssh > > connection tunneled through wireguard gets stuck (reproducible). An echo > > of a very long line (e.g. 4096 chars) is sufficient. > > > > The weird part is, MTU 1420 works fine for wireguard on MacOS. How comes > > that Wireguard appears to be more stable on MacOS than on Linux? > > WireGuard works just fine for me on Linux using MTU 1432 if over IPv4, and > 1412 if over IPv6. The underlying PPPoE device MTU is 1492 in my case. Check > which PPPoE MTU you use in Linux vs in MacOS. > Oh, and I just remembered -- you're better off setting the same MTU on the entire WG network, i.e. substract those 8 bytes of PPPoE interface on the remote host's WG interface as well. Else the local interface MTU will need a weird and so far unexplained further 4-byte reduction for things to work: https://lists.zx2c4.com/pipermail/wireguard/2019-April/004078.html -- With respect, Roman