OpenNTPD

From Infogalactic: the planetary knowledge core
Jump to: navigation, search
OpenNTPD
300px
"Saving the world again... on time"
Developer(s) The OpenBSD Project
Stable release 5.9p1 / 29 March 2016; 8 years ago (2016-03-29)
Development status Active
Written in C
Operating system BSD, Linux, Solaris and OS X[1]
Type Time synchronization
License ISC
Website www.openntpd.org
Standard(s) RFC 1305, RFC 5905
As of April 2016

OpenNTPD is a Unix system daemon implementing the Network Time Protocol to synchronize the local clock of a computer system with remote NTP servers. It is also able to act as an NTP server to NTP-compatible clients.

OpenNTPD is primarily developed by Henning Brauer as part of the OpenBSD project. Its design goals include being secure (non-exploitable), easy to configure, and accurate enough for most purposes. Its portable version, like that of OpenSSH,[2] is developed as a child project which adds the portability code to the OpenBSD version and releases it separately. The portable version is developed by Brent Cook.[3] The most recent portable version was released in 2016. The project developers receive some funding from the OpenBSD Foundation.

History

The development of OpenNTPD was motivated by a combination of issues with current NTP daemons: difficult configuration, complicated and difficult to audit code, and unsuitable licensing.[4] OpenNTPD was designed to solve these problems and make time synchronization accessible to a wider userbase. After a period of development, OpenNTPD first appeared in OpenBSD 3.6.[5] Its first release was announced on 2 November 2004.[6]

Goals

OpenNTPD is an attempt by the OpenBSD team to produce an NTP daemon implementation that is secure, simple to audit, trivial to set up and administer, reasonably accurate, and light on system resources. As such, the design goals for OpenNTPD are: security, ease of use, and performance.[7] Security in OpenNTPD is achieved by robust validity check in the network input path, use of bounded buffer operations via strlcpy, and privilege separation to mitigate the effects of possible security bugs exploiting the daemon through privilege escalation. In order to simplify the use of NTP, OpenNTPD implements a smaller set of functionalities than those available in other NTP daemons, such as that provided by the Network Time Protocol Project. The objective is to provide enough features to satisfy typical usage at the risk of unsuitability for esoteric or niche requirements. OpenNTPD is configured through the configuration file, ntpd.conf.[8] A minimal number of options are offered: IP address or hostname on which OpenNTPD should listen, a timedelta sensor device to be used, and the set of servers from which the time will be synchronized. The accuracy of OpenNTPD is best-effort; the daemon attempts to be as accurate as possible but no specific accuracy is guaranteed.

Example

OpenNTPD gradually adjusts the system clock, as seen here in the output of OpenNTPD running on an Arch Linux system:

$ grep ntpd /var/log/daemon.log | grep adjusting | tail
Aug  4 03:32:20 nikolai ntpd[4784]: adjusting local clock by -1.162333s
Aug  4 03:36:08 nikolai ntpd[4784]: adjusting local clock by -1.023899s
Aug  4 03:40:02 nikolai ntpd[4784]: adjusting local clock by -0.902637s
Aug  4 03:43:43 nikolai ntpd[4784]: adjusting local clock by -0.789431s
Aug  4 03:47:35 nikolai ntpd[4784]: adjusting local clock by -0.679320s
Aug  4 03:50:45 nikolai ntpd[4784]: adjusting local clock by -0.605858s
Aug  4 03:53:31 nikolai ntpd[4784]: adjusting local clock by -0.529821s
Aug  4 03:56:33 nikolai ntpd[4784]: adjusting local clock by -0.429573s
Aug  4 03:59:46 nikolai ntpd[4784]: adjusting local clock by -0.312575s
Aug  4 04:03:14 nikolai ntpd[4784]: adjusting local clock by -0.232646s
$

Criticism

OpenNTPD has been criticized as being less accurate than the NTP daemon produced by Internet Software Consortium (ISC).[9] Internally, OpenNTPD does not maintain millisecond accuracy and can vary 50-200ms from "real" time because it omits a variety of algorithms that increase accuracy in favour of code simplicity. The OpenNTPD project acknowledged the criticism, but pointed out that the lack of microsecond precision was a design tradeoff that benefited simplicity and security.[9] The OpenNTPD design goals state the project's intent is to "[r]each a reasonable accuracy" without sacrificing "secure design for getting that last nanosecond or obscure edge case."[10]

In September 2004, shortly after the release of OpenNTPD 3.6, ISC NTP contributor Brad Knowles published an article entitled OpenNTPd Considered Harmful[11] criticizing various aspects of OpenNTPD's implementation of the NTP protocol, as well as the split development model that the project employs, which is also used in the development of OpenSSH and OpenBGPD. In December 2004, Darren Tucker, the principal developer on the portable branch of OpenNTPD, wrote a detailed response to Knowles, acknowledging some issues as valid, rejecting several others as unwarranted, and considering yet others as misleading.[12] Among the more serious issues raised by Knowles was that OpenNTPD servers claimed to be stratum 1 servers. The issue had however already been fixed by the time of Tucker's response. In March 2005, Knowles acknowledged Tucker's response, and stated that he was "going to do everything [he could] to work with [Tucker] to get any remaining issues resolved."[13] Additionally, the OpenBSD networking FAQ was expanded with a responds to Knowles' initial criticism.[14]

As of August 2007, OpenNTPD 3.9p1 still served time with a zero dispersion.[15]

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ ntpd.conf(5) – OpenBSD File Formats Manual. 26 May 2006. Retrieved 16 September 2006.
  9. ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found..
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

Retrieved from "https://infogalactic.com/w/index.php?title=OpenNTPD&oldid=720992080"