Dave Evans offers the following royalty-free article for you to publish online or in print. Feel free to use this article in your newsletter, website, ezine, blog, or forum. ----------- PUBLICATION GUIDELINES - You have permission to publish this article for free providing the "About the Author" box is included in its entirety. - Do not post/reprint this article in any site or publication that contains hate, violence, porn, warez, or supports illegal activity. - Do not use this article in violation of the US CAN-SPAM Act. If sent by email, this article must be delivered to opt-in subscribers only. - If you publish this article in a format that supports linking, please ensure that all URLs and email addresses are active links. - Please send a copy of the publication, or an email indicating the URL to [email protected] - Article Marketer (www.ArticleMarketer.com) has distributed this article on behalf of the author. Article Marketer does not own this article, please respect the author's copyright and publication guidelines. If you do not agree to these terms, please do not use this article. ----------- Article Title: How to Obtain Status and Synchronization Information From a NTP Server Author: Dave Evans Category: Networks, Operating Systems, Software Word Count: 779 Keywords: NTP Server, Atomic Clock, Atomic Time, GPS NTP Server, NTP Time Server, Time Server, Time Synchronis Author's Email Address: [email protected] Article Source: http://www.articlemarketer.com ------------------ ARTICLE START ------------------
NTP, or Network Time Protocol, is used widely to disseminate accurate time around the Internet and other computer networks. The protocol is used to synchronise network time clients to a precise time server. This article provides an overview of how to find and solve synchronisation issues with NTP servers. NTP was first developed over 25 years ago to synchronise time critical processes across the Internet. It was originally developed for the LINUX operating system, but has since been ported to Windows. The source code is freely download able from the NTP website as 'open source' under the GNU public licence. Instructions on how to configure, compile and install the software are available with the software package. Here, I have attempted to shed light on a few problems that can arise after installation. When NTP is compiled and installed, correct operation needs to be verified. A number of tools are included in the distribution that can be used to query and debug a NTP server. The most commonly used tool is the 'ntpq' utility - the NTP query application. 'Ntpq' can be run on the host NTP installation or from any other computer on the network. The utility can be used to inspect NTP Server system variables to verify correct operation. The utility is run from a Linux command prompt. It is controlled by a number of command line parameters. The most useful being the 'peer' option that displays NTP server peer variables. The peer option is specified using the '-p' parameter, thus: ntpq -p 192.168.0.201 # where 192.168.0.201 is the IP address of the queried NTP server. If the utility is run directly from the host NTP server, the IP address may be omitted. Output similar to the information below may be generated. remote refid st t when poll reach delay offset jitter *127.127.0.32 .GPS. 1 u 18 64 377 0.000 0.412 0.015 +127.127.0.7 .MSF. 1 u 18 64 377 1.622 0.546 1.125 This first character on the left indicates the synchronization status of each reference clock in the list. An asterisk indicates the reference clock that is currently being used for synchronization. Additional reference clocks, marked with a '+', are also used in the time synchronization algorithm, while peers marked with any other symbol remain unused. There are a number of other fields indicating reference clock status information. The 'remote' address corresponds to each server or peer reference clock entry used by the server. The 'refid' field indicates the time source utilised. The 'st' field indicates the stratum, 't' indicates type; unicast, multicast or local. The 'when' field indicates the time since the reference was last contacted. The 'poll' field indicates the polling frequency of the reference. The 'delay' field provides the round-trip delay when contacting the reference. The 'offset' field is the offset between the reference time and the server time. The 'jitter' field indicates the dispersion of time stamps received from the reference. In the event of problems synchronising to a reference peer, a four-character status string is entered in the 'refid' field. The status fields may consist of one of: ACST - The association belongs to a anycast server. AUTH - Server authentication failed. AUTO - Autokey sequence failed. BCST - The association belongs to a broadcast server. CRYP - Cryptographic authentication or identification failed. The details should be in the system log file or the cryptostats statistics file, if configured. No further messages will be sent to the server. DENY - Access denied by remote server. No further messages will be sent to the server. DROP - Lost peer in symmetric mode. Please wait while the association is restarted. RSTR - Access denied due to local policy. No further messages will be sent to the server. INIT - The association has not yet synchronized for the first time. MCST - The association belongs to a manycast server. NKEY - No key found. Either the key was never installed or is not trusted. RATE - Rate exceeded. The server has temporarily denied access because the client exceeded the rate threshold. RMOT - Somebody is tinkering with the association from a remote host running ntpdc. Not to worry unless some rascal has stolen your keys. STEP - A step change in system time has occurred, but the association has not yet resynchronized. To summarise, the NTP query utility is an often overlooked, but invaluable tool for debugging NTP server systems. As well as being able to assess the current status of a server, it can provide invaluable precision and offset information for each reference clock in use. If you would like more information to read more articles on how to configure and install network time servers and NTP server systems, please visit: http://www.timetools.co.uk/ ------------------ ARTICLE END ------------------ [Non-text portions of this message have been removed]
