From owner-freebsd-net@freebsd.org Thu Jun 29 19:53:14 2017 Return-Path: Delivered-To: freebsd-net@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 DFC3CDA4A6E for ; Thu, 29 Jun 2017 19:53:14 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id CA3D372051 for ; Thu, 29 Jun 2017 19:53:14 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id v5TJrEBP037116 for ; Thu, 29 Jun 2017 19:53:14 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-net@FreeBSD.org Subject: [Bug 220351] Path MTU discovery works only after resetting an internal interface MTU (mpd5, ng_nat, ipfw) Date: Thu, 29 Jun 2017 19:53:14 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 11.0-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: eugen@freebsd.org X-Bugzilla-Status: Open X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: eugen@freebsd.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: assigned_to bug_status cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Jun 2017 19:53:15 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D220351 Eugene Grosbein changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|freebsd-net@FreeBSD.org |eugen@freebsd.org Status|New |Open CC| |eugen@freebsd.org --- Comment #2 from Eugene Grosbein --- (In reply to Martin Birgmeier from comment #1) Lowering interface MTU of internal machine also lowers its default route 'm= tu' attribute, see output of the command 'route -n get default'. Raising interface MTU back does NOT restore 'mtu' attribute of the default route, so the kernel still uses 1492 as maximum IP packet size for packets going via this route. Correct solution for your problem is 'set iface enable tcpmssfix' command in the mpd.conf, see /usr/local/etc/mpd5/mpd.conf.sample for example. This way= you can keep default MTU=3D1500 for internal hosts and have no MTU-related netw= ork problems. Please test and report back. --=20 You are receiving this mail because: You are the assignee for the bug.=