linux-kernel - RE: ntp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <MDEHLPKNGKAHNMBLJOLKCELPBFAC.davids@webmaster.com>
Date:	Sat, 3 Feb 2007 23:59:56 -0800
From:	"David Schwartz" <davids@...master.com>
To:	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: RE: ntp

> When i start the ntp service successful on server, the client must ntpdate
> with the server after waiting a moment.
> The moment may be 3~5 minutes, or it may be 10~15 minutes. I
> don't know why
> it happens?

Two clocks cannot be synchronized instantaneously. It takes time to compare
the two clocks and adjust so that they stay in sync. A client will not
accept a date from an NTP server whose clock is not synchronized -- why
should it?

Imagine this -- you have a clock you do not trust. You ask a clock you do
trust what time it is, and it tells you it is 10:00. A bit later, I ask you
what time it is. Your clock says 10:12. Can you trust that time? Your clock
may be fast, it may be slow. You don't know. Until you check the clock you
trust a few times and confirm both clocks are flowing at the same rate, you
cannot tell the client what time it is when it asks you.

DS

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/