summary: SNTP installation and configuration for Windows XP last updated: Tuesday, July 16, 2002 prepared by: jtk test hardware: Gateway E3600 test OS: XP professional, Version 2002 -------- Overview -------- Having an accurate notion of time has long been a desirable feature for computers and operating systems. As more computers are networked, it is important that network applications, by they client/server or peer-to-peer, have a similar notion of time. This is especially important for security, auditing/accounting, authentication and file services. In order to provide highly accurate network time to campus hosts, the Networks & Telecom group operates network time protocol (NTP) servers, synchronized to very accurate stratum-2 servers at Argonne National Laboratories and the University of Illinois, Urbana-Champaign. Accurate time is then distributed using NTP to hosts within the DePaul campus. NTP is able to provide accurate time within a millisecond of a central server. Hosts such as Windows XP use a light version of NTP called Simple NTP or SNTP for short. SNTP is easily configured on end hosts and assures that they have highly accurate clocks all the time. All that is required is a standard network connection with access to poll the University's designated NTP servers. ------------ Requirements ------------ You must be logged onto the system with administrator privileges. Windows Time Service must be automatically started so changes will take effect after a reboot. To verify the service is started automatically, do the following: 1. From the Windows desktop, click the Start -> Settings -> Control Panel. 2. Double click the Administrative Tools icon. 3. Double click the Services shortcut icon. 4. Scroll down in the Services panel until you see the Windows Time service listed. Double click on the Windows Time service. 5. If the Service Type is equal to "Automatic" and the Service Status is equal to "Started", the time service is already setup properly. Click Cancel and close the windows opened by the previous steps. Skip to the Configuration process in the next section. 6. If Service Type is not equal to "Automatic", click the drop down box and select "Automatic". 7. If Service Type is not equal to "Started", click the Start button. 8. Return to step 5 to verify that the service is now running automatically and then proceed to the Configuration process below. ------------- Configuration ------------- 1. From the Windows desktop, click Start -> Run. 2. In the "Open:" text box, enter: cmd 3. Hit the ENTER key or click OK. 4. At the command prompt enter the command: net time /setsntp:"ntp1.depaul.edu ntp2.depaul.edu" 5. If the system responds that the "command completely successfully", at the command prompt enter the command: net stop w32time 6. If the system responds that the "service was stopped successfully", at the command prompt enter the command: net start w32time 7. The configuration process is complete. --------------- Troubleshooting --------------- If time synchronization fails, ensure that ntp1.depaul.edu or ntp2.depaul.edu is reachable. Run the following at a command prompt to verify connectivity: ping ntp1.depaul.edu ping ntp2.depaul.edu ----- Notes ----- The Internet Connection Firewall will NOT prevent time synchronization from working, since the host initiates the initial time sync request, the firewall will allow a returning response for receiving the time update message from the server. The default time polling schedule is every 7 days. This is fairly long. It may turn out that a shortened time polling period would be preferable. Tuning the time polling period requires changes to the registry. We want to use default settings whenever possible so we opted not to recommend changing the registry setting at this time. The registry key controlling the polling interval is located in: HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Services\ W32Time\ TimeProviders\ NtpClient The key is "SpecialPollInterval". The value data is the time in seconds between polls. The default value in decimal, "604800" is a poll interval of 7 days. Warning, change this setting at your own risk! Another useful registry setting lists configured time servers. At this time we do not recommend changing the default time server, but in the future we may add secondary and tertiary servers. ---------- References ---------- Configuring Windows 2000 and Windows XP to use NIST Time Servers A detailed description of setting up Windows Time services to NIST. http://www.boulder.nist.gov/timefreq/pdf/wind2000xp.pdf [note: this document was largely based on NIST's document] The Windows Time Service, Windows 2000 White Paper A detailed description of how time synchronization operates on Windows http://www.microsoft.com/windows2000/techinfo/howitworks/security/wintimeserv.asp Time Synchronization Server information page Details on the Network Time Protocol (NTP) and related time sync info http://www.ntp.org Network Time Protocol (Version 3), Specification, Implementation and Analysis Internet Engineering Task Force (IETF) RFC 1305, D. Mills ftp://ftp.isi.edu/in-notes/rfc1305.txt Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI Internet Engineering Task Force (IETF) RFC 2030, D. Mills ftp://ftp.isi.edu/in-notes/rfc2030.txt DePaul Networks & Telecom Homepage http://networks.depaul.edu ------- Changes ------- 2002-07-08 Document creation date 2002-07-09 Minor edits 2002-07-16 Added secondary server ntp2.depaul.edu and removed alt. config