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 40452C433EF for ; Mon, 21 Feb 2022 19:57:15 +0000 (UTC) Received: by lists.zx2c4.com (OpenSMTPD) with ESMTP id 61c2f047; Mon, 21 Feb 2022 19:57:14 +0000 (UTC) Received: from rin.romanrm.net (rin.romanrm.net [2001:bc8:2dd2:1000::1]) by lists.zx2c4.com (OpenSMTPD) with ESMTPS id f69adcf6 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO) for ; Mon, 21 Feb 2022 19:57:12 +0000 (UTC) Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by rin.romanrm.net (Postfix) with SMTP id 93FE85D4; Mon, 21 Feb 2022 19:57:11 +0000 (UTC) Date: Tue, 22 Feb 2022 00:57:10 +0500 From: Roman Mamedov To: Michael Tokarev Cc: wireguard@lists.zx2c4.com Subject: Re: WireGuard Windows should have default MTU of 1280. Message-ID: <20220222005710.705a7023@nvm> In-Reply-To: <6ba013e9-05db-17bc-995b-11ef1f279c91@msgid.tls.msk.ru> References: <6ba013e9-05db-17bc-995b-11ef1f279c91@msgid.tls.msk.ru> 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 Mon, 21 Feb 2022 22:16:22 +0300 Michael Tokarev wrote: > 21.02.2022 22:11, Michael Adams wrote: > > Throwing in my two cents: I was using MTU 1280 on Tinc a few years back, for IPv6 VPN support on Windows & Linux. It's good practice. > > Lemme guess. The OP is routing wg packets over IPv6? Can this be > the problem here, because V6 has larger overhead so that 1420 is > too large to fit into 1500 bytes together with IPv6 header? 1420 is picked specifically so that it fits into a 1500 byte packet with IPv6. If you run WG exclusively over IPv4, you can use up to 1432. However, if your ISP uses, say, PPPoE or L2TP, you need to reduce these numbers accordingly, as the underlying interface will not have the full 1500 byte MTU. -- With respect, Roman