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 »
Precision and time synchronisation is highly important for modern computer networks, without synchronisation many time sensitive transactions would be impossible to carry out.
The internal clock in computers does keep time and date information but these Real Time Chips are not designed to keep perfect time as computers are mass produced and optimized for low cost rather than being perfect clocks.
Of course for a lot of applications this can be more than adequate but for time-sensitive transactions such as online purchasing not having a network that is synchronised can cause errors in transactions and can even leave the network vulnerable to fraud.
Fortunately Windows Server from 2000 onwards has a time synchronisation utility built in call windows time (w32time.exe) this can be configured to allow the machine to be used as time server.
Windows time uses a form of NTP (Network Time Protocol) which was developed over 20 years ago. It uses an algorithm to synchronise time on a network. NTP (version 4) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.
NTP uses a single time reference and synchronises all machines on the network to that time. It can be configured to both synchronise a network using Continue reading »