From nobody Thu Jun 22 16:38:47 2023 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Qn5fW5PFvz4gl7X; Thu, 22 Jun 2023 16:38:43 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [50.1.20.27]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "www.zefox.com", Issuer "www.zefox.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Qn5fW2Bs4z3CZT; Thu, 22 Jun 2023 16:38:43 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Authentication-Results: mx1.freebsd.org; none Received: from www.zefox.net (localhost [127.0.0.1]) by www.zefox.net (8.17.1/8.15.2) with ESMTPS id 35MGclE9060658 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 22 Jun 2023 09:38:48 -0700 (PDT) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.17.1/8.15.2/Submit) id 35MGclTw060657; Thu, 22 Jun 2023 09:38:47 -0700 (PDT) (envelope-from fbsd) Date: Thu, 22 Jun 2023 09:38:47 -0700 From: bob prohaska To: Jamie Landeg-Jones Cc: freebsd-net@freebsd.org, freebsd-arm@freebsd.org Subject: Re: -current dropping ssh connections Message-ID: References: <202306212305.35LN5ITH069587@donotpassgo.dyslexicfish.net> List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=unknown-8bit Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <202306212305.35LN5ITH069587@donotpassgo.dyslexicfish.net> X-Rspamd-Queue-Id: 4Qn5fW2Bs4z3CZT X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:7065, ipnet:50.1.16.0/20, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-ThisMailContainsUnwantedMimeParts: N On Thu, Jun 22, 2023 at 12:05:18AM +0100, Jamie Landeg-Jones wrote: > bob prohaska wrote: > > > I can't detect any consistent pattern. For a while I thought load on the > > sshd-host end made a difference, but the latest disconnect was on an idle > > system with serial console output the only traffic on the dropped connection. > > Could it be that the serial connection is sending the ssh-escape sequence? > > Try adding "-e none" to the initial ssh connection command. That seems worth a try. The notion of an ssh escape (~. in this case) finding its way into the data stream is new to me. Since the last reboot to FreeBSD nemesis.zefox.com 14.0-CURRENT FreeBSD 14.0-CURRENT #70 main-476f61217b: Tue Jun 20 16:06:46 PDT 2023 bob@nemesis.zefox.com:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC arm64 the ssh-to-tip connection has stayed up with the end running tip unloaded. I'll try adding a load (buildworld) later today to see if that makes a difference. Sometimes stray characters do appear on the tip connection on re-establishment, for example: root@nemesis:/home/bob # tip ucom Stale lock on cuaU0 PID=1238... overriding. connected FreeBSD/arm (ns2.zefox.net) (ttyu0) login: � ѥ����ѥ��� �����ѥ������͕����ɕ��ѕ�����5)5)�Password: Login incorrect login: The actual display on the ssh client (A Pi4 running RasPiOS) is of charcters resembling a dark question mark in a white oval and small non-Latin characters which apparently can't be copied and pasted. They're less random that what's usually seen with a baud mismatch and at least sometimes (as the example above) seem to get mistaken for a login attempt or command by the serial console process being connected to. This sort of rubbish isn't seen after the connection comes up; it's only found on (re)-connection. Thanks for writing, bob prohaska