From owner-freebsd-questions@freebsd.org Wed Jun 7 17:45:23 2017 Return-Path: Delivered-To: freebsd-questions@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 BF37DD143A0 for ; Wed, 7 Jun 2017 17:45:23 +0000 (UTC) (envelope-from freebsd@qeng-ho.org) Received: from bede.home.qeng-ho.org (bede.qeng-ho.org [217.155.128.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "fileserver.home.qeng-ho.org", Issuer "fileserver.home.qeng-ho.org" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 640387C774 for ; Wed, 7 Jun 2017 17:45:22 +0000 (UTC) (envelope-from freebsd@qeng-ho.org) Received: from arthur.home.qeng-ho.org (arthur.home.qeng-ho.org [172.23.1.2]) by bede.home.qeng-ho.org (8.15.2/8.15.2) with ESMTP id v57Hh3PH001052 for ; Wed, 7 Jun 2017 18:43:03 +0100 (BST) (envelope-from freebsd@qeng-ho.org) To: FreeBSD-Questions From: Arthur Chance Subject: /dev/null behaving strangely Message-ID: Date: Wed, 7 Jun 2017 18:43:03 +0100 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Jun 2017 17:45:23 -0000 My main fileserver is showing very strange symptoms. It's running 10.3-RELEASE-p18, GENERIC kernel, amd64. I can't get a uname from it into this mail as this is from another box and neither ssh nor scp work to the file server. It started about 20 minutes ago when I got mail from cron ---- From: operator@bede.home.qeng-ho.org (Cron Daemon) To: operator@bede.home.qeng-ho.org Subject: Cron /usr/libexec/save-entropy Date: Wed, 07 Jun 2017 18:22:00 +0100 /usr/libexec/save-entropy: cannot create /dev/null: Permission denied ---- This is now happening every 10 minutes as the cron job runs. However, running save-entropy from the command line (on the console, or over ssh before I rebooted) works without complaint. Since I rebooted I cannot ssh or scp to the file server, getting the errors arthur@arthur[7]> ssh root@fileserver Couldn't open /dev/null: Permission denied arthur@arthur[4]> scp fileserver:/tmp/t /tmp/t Couldn't open /dev/null: Permission denied ls -l /dev/null gives a possibly interesting result: on two other boxes I get root@arthur:3# ls -l /dev/null crw-rw-rw- 1 root wheel 0x1f 7 Jun 18:05 /dev/null but on the file server the device number is 0xd rather than 0x1f (owner, group and permissions are identical). I'm not sure if this is significant. Rebooting the file server has had no effect on the problem, other than cutting off ssh access. The system disk is a relatively new SSD and smartctl shows no problems with it. devfs mounting on /dev is the default set up, and now jails are running to confuse things. Any ideas? -- An amusing coincidence: log2(58) = 5.858 (to 0.0003% accuracy).