From owner-freebsd-security@freebsd.org Thu Jul 2 01:52:54 2015 Return-Path: Delivered-To: freebsd-security@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 D7ADA992A69 for ; Thu, 2 Jul 2015 01:52:54 +0000 (UTC) (envelope-from wollman@hergotha.csail.mit.edu) Received: from hergotha.csail.mit.edu (wollman-1-pt.tunnel.tserv4.nyc4.ipv6.he.net [IPv6:2001:470:1f06:ccb::2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 7C07916A6 for ; Thu, 2 Jul 2015 01:52:54 +0000 (UTC) (envelope-from wollman@hergotha.csail.mit.edu) Received: from hergotha.csail.mit.edu (localhost [127.0.0.1]) by hergotha.csail.mit.edu (8.14.9/8.14.9) with ESMTP id t621qmnX013847; Wed, 1 Jul 2015 21:52:48 -0400 (EDT) (envelope-from wollman@hergotha.csail.mit.edu) Received: (from wollman@localhost) by hergotha.csail.mit.edu (8.14.9/8.14.4/Submit) id t621qk6Q013842; Wed, 1 Jul 2015 21:52:46 -0400 (EDT) (envelope-from wollman) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <21908.39278.416719.875140@hergotha.csail.mit.edu> Date: Wed, 1 Jul 2015 21:52:46 -0400 From: Garrett Wollman To: Peter Jeremy Cc: "freebsd-security@freebsd.org" Subject: Re: Leap Second In-Reply-To: <20150701202728.GA9532@server.rulingia.com> References: <1435154274.964221.306546033.052903CD@webmail.messagingengine.com> <86bnfwxa4m.fsf@nine.des.no> <1435758941.105242.312562265.3103CECB@webmail.messagingengine.com> <20150701202728.GA9532@server.rulingia.com> X-Mailer: VM 7.17 under 21.4 (patch 22) "Instant Classic" XEmacs Lucid X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (hergotha.csail.mit.edu [127.0.0.1]); Wed, 01 Jul 2015 21:52:48 -0400 (EDT) X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED, HEADER_FROM_DIFFERENT_DOMAINS autolearn=disabled version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on hergotha.csail.mit.edu X-Mailman-Approved-At: Thu, 02 Jul 2015 03:55:52 +0000 X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Security issues \[members-only posting\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Jul 2015 01:52:54 -0000 < said: > ntpd(8) has provision for specifying a leapsecond file which presumably > makes it leap-second aware. I haven't looked into the details. The current NTP protocol, as implemented by ntpd, distributes leap-second information if provided. This information may be provided by higher-stratum (upstream) NTP servers, or by using the "leapfile" configuration statement in ntp.conf to specify a local copy of the leapseconds file in NIST/USNO format. No such file is provided by default. We could easily do so, but shouldn't, because that file would take precedence over the leap indicator learned from higher-stratum servers, and that's not desirable for clients. If you're running a bunch of servers, you should distribute and install the leapseconds file using your configuration-management system. (For example, my puppet module for NTP, which we use at CSAIL for three NTP servers, does so: .) -GAWollman