NTP or Network Time Protocol to give it its full name is an internet protocol designed to distribute precise time around a network. NTP is a UDP based protocol used to synchronize system time on network infrastructure, such as servers, workstations and network equipment .
This article describes how to utilise the Network Time Protocol authentication features to authenticate time references when synchronizing clients to a NTP Server.
NTP Server Security
Network Time Protocol is used to provide a precise time reference for time critical applications. Therefore, NTP can pose a security risk if malicious users attempt to corrupt a NTP timestamp to create a false time on network equipment.
NTP provides increased security in the form of authentication. Authentication is intended to overcome security risks by ensuring that any response received from an NTP time server has come from the intended reference. The client sends a request for time to a NTP server. The server then responds to the client with a precise timestamp along with one of a number of agreed encrypted keys. On receipt of the timestamp, the client un-encrypts the key and verifies it against a list of trusted keys. The client can then be sure t Continue reading »
NTP or Network Time Protocol servers are network devices that are designed to distribute accurate time to network time clients and other network infrastructure. This article describes how to configure and install NTP server systems on a network and discusses the advantages and disadvantages of various reference clock options.
NTP servers are generally supplied as 1U high rack mountable network devices. They obtain an accurate time from an external time reference, such as GPS or radio, and provide an accurate timing resource for a computer network. NTP or Network Time Protocol is a protocol designed for distributing time to client computers over an IP network. The protocol is UDP based and as such requires the TCP/IP network infrastructure to be installed.
Hardware Installation
Stratum 1 NTP time servers rely on an external timing reference to obtain accurate time. Various external timing references are available. Options may vary with the installations regional location.
GPS (Global Positioning System) is a popular timing reference. The advantages of a GPS reference are that it is highly accurate and can be utilised anywhere in the world. A typical GPS NTP server installation can synchronise to within a few microseconds of UTC time. The disadvantage of GPS is that ideally a roof-mounted external antenna is required with a good view of the sky. The maximum cabling distance between an NTP Continue reading »
The Microsoft Windows operating systems from Windows 2000 onwards has a built-in time synchronization service – ‘Windows Time’. This article describes how to configure the Microsoft Windows 2003 and Windows 2000 time service as a NTP time server. It shows how to modify registry entries to configure the Microsoft Windows Time Service. The Windows Time service allows a Windows network to provide synchronisation of all machines within a domain.
Windows 2003 Server Configuration
Windows 2003 has expanded on the original Windows 2000 time service by providing a true NTP implementation. The time service, installed by default, can synchronise to a NTP Server. Indeed, by manipulating registry settings for the service it can act as both an NTP server and client to synchronise other network clients in the domain.
The ‘Windows Time’ service should be present in the systems service list. The application executable is ‘w32time.exe’. The parameter list for w32time can be found in the registry at:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Time
Before modifying registry entries it is good a dood idea to backup the registry settings. The registry can then be restored in the event of problems being encountered.
To configure a Windows 2003 machine to synchronise to an external NTP server, edit the following registry entries:
HKEY_LOCAL_MACHI Continue reading »