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diff --git a/html/release.htm b/html/release.htm new file mode 100644 index 0000000..9dcef7c --- /dev/null +++ b/html/release.htm @@ -0,0 +1,290 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> +<head> +<meta name="generator" content="HTML Tidy, see www.w3.org"> +<title>NTP Version 4 Release Notes</title> +</head> +<body> +<h3>NTP Version 4 Release Notes</h3> + +<img align="left" src="pic/hornraba.gif" alt="gif"><a href= +"http://www.eecis.udel.edu/~mills/pictures.htm">from <i>Alice's +Adventures in Wonderland</i>, Lewis Carroll</a> + +<p>The rabbit toots to make sure you read this.<br clear="left"> +</p> + +<hr> +<p>This document was last updated 4 May 2001</p> + +<h4>NTP Version 4 Release Notes</h4> + +<p>This release of the NTP Version 4 (NTPv4) daemon for Unix, VMS +and Windows (NT4 and 2000) incorporates new features and +refinements to the NTP Version 3 (NTPv3) algorithms. However, it +continues the tradition of retaining backwards compatibility with +older versions, except for symmetric mode in NTPv1. Client/server +mode continues to be supported in NTPv1. The NTPv4 version has been +under development for quite a while and isn't finished yet. In +fact, quite a number of NTPv4 features have already been +retrofitted in the current NTPv3, although this version is not +actively maintained by the NTPv4 developer's group.</p> + +<p>The primary purpose of this release is to verify the remaining +new code compiles and runs in the various architectures, operating +systems and hardware complement that can't be verified here. Of +particular interest are Windows 2000, VMS and various reference +clock drivers. As always, corrections and bugfixes are warmly +received, especially in the form of context diffs.</p> + +<p>This note summarizes the differences between this software +release of NTPv4, called ntp-4.x.x, and the previous NTPv3 version, +called xntp3-5.x.x. Additional information on protocol +compatibility details is in the <a href="biblio.htm">Protocol +Conformance Statement</a> page.</p> + +<ol> +<li> +<p>Most calculations are now done using 64-bit floating double +format, rather than 64-bit fixed point format. The motivation for +this is to reduce size, improve speed and avoid messy bounds +checking. Workstations of today are much faster than when the +original NTP version was designed in the early 1980s, and it is +rare to find a processor architecture that does not support +floating double. The fixed point format is still used with raw +timestamps, in order to retain the full precision of about 212 +picoseconds. However, the algorithms which process raw timestamps +all produce fixed point differences before converting to floating +double. The differences are ordinarily quite small so can be +expressed without loss of accuracy in this format.</p> +</li> + +<li> +<p>The clock discipline algorithm has been redesigned to improve +accuracy, reduce the impact of network jitter and allow an increase +in poll intervals to well over one day with only moderate sacrifice +in accuracy. The NTPv4 design allows servers to increase the poll +intervals even when synchronized directly to the peer. In NTPv3 the +poll interval in such cases was clamped to the minimum, usually 64 +s. For those servers with hundreds of clients, the new design can +dramatically reduce the network load.</p> +</li> + +<li> +<p>This release includes support for the <a href= +"http://www.eecis.udel.edu/~mills/resource.htm"><i> +nanokernel</i></a> precision time kernel support, which is now in +stock Linux and FreeBSD kernels. If a precision time source such as +a GPS timing receiver or cesium clock is available, kernel +timekeeping can be improved to the order less than one microsecond. +The older precision time kernel for the Alpha continues to be +supported.</p> +</li> + +<li> +<p>This release includes support for Autokey public-key +cryptography, which is the preferred scheme for authenticating +servers to clients. It uses NTP header extensions fields documented +in: Mills, D.L. Public-Key cryptography for the Network Time +Protocol. Internet Draft draft-ietf-stime-ntpauth-00.txt, +University of Delaware, June 2000, 36 pp. <a href= +"http://www.eecis.udel.edu/~mills/database/memos/draft-ietf-stime-ntpauth-00.txt"> +ASCII</a> and implemented in this release. The design provides for +orderly key refreshment and does not require public keys and +related media to be copied from one machine to another. Specific +information about Autokey cryptography is contained in the <a href= +"authopt.htm">Authentication Options</a> page and links from +there.</p> +</li> + +<li> +<p>NTPv4 includes two new association modes which in most +applications can avoid per-host configuration altogether. Both of +these are based on IP multicast technology and Autokey +cryptography. They provide for automatic discovery and +configuration of servers and clients without identifying servers or +clients in advance. In multicast mode a server sends a message at +fixed intervals using specified multicast group addresses, while +clients listen on these addresses. Upon receiving the message, a +client exchanges several messages with the server in order to +calibrate the multicast propagation delay between the client and +server. In manycast mode a client sends a message to a specified +multicast group address and expects one or more servers to reply. +Using engineered algorithms, the client selects an appropriate +subset of servers from the messages received and continues in +ordinary client/server operation. The manycast scheme can provide +somewhat better accuracy than the multicast scheme at the price of +additional network overhead. See the <a href="assoc.htm"> +Association Management</a> page for further information.</p> +</li> + +<li> +<p>There are two burst mode features available where special +conditions apply. One of these is enabled by the <tt>iburst</tt> +keyword in the <tt>server</tt> configuration command. It is +intended for cases where it is important to set the clock quickly +when an association is first mobilized. The other is enabled by the +<tt>burst</tt> keyword in the <tt>server</tt> configuration +command. It is intended for cases where the network attachment +requires an initial calling or training procedure. See the <a href= +"assoc.htm">Association Management</a> page for further +information.</p> +</li> + +<li> +<p>The reference clock driver interface is smaller, more rational +and more accurate. Support for pulse-per-second (PPS) signals has +been extended to all drivers as an intrinsic function. Most of the +drivers in NTPv3 have been converted to this interface, but some, +including the PARSE subinterface, have yet to be overhauled. New +drivers have been added for several GPS receivers now on the market +for a total of 39 drivers. Drivers for the Canadian standard time +and frequency station CHU, the US standard time and frequency +stations WWV/H and for IRIG signals have been updated and +capabilities added to allow direct connection of these signals to +the Sun audio port <tt>/dev/audio</tt>.</p> +</li> + +<li> +<p>In all except a very few cases, all timing intervals are +randomized, so that the tendency for NTPv3 to self-synchronize and +bunch messages, especially with a large number of configured +associations, is minimized.</p> +</li> + +<li> +<p>In NTPv3 a large number of weeds and useless code had grown over +the years since the original NTPv1 code was implemented almost +twenty years ago. Using a powerful weedwacker, much of the +shrubbery has been removed, with effect a substantial reduction in +size of almost 40 percent.</p> +</li> + +<li> +<p>The entire distribution has been converted to gnu <tt> +automake</tt>, which should greatly ease the task of porting to new +and different programming environments, as well as reduce the +incidence of bugs due to improper handling of idiosyncratic kernel +functions.</p> +</li> +</ol> + +<h4>Nasty Surprises</h4> + +<p>There are a few things different about this release that have +changed since the latest NTP Version 3 release. Following are a few +things to worry about:</p> + +<ol> +<li> +<p>As required by Defense Trade Regulations (DTR), the +cryptographic routines supporting the Data Encryption Standard +(DES) have been removed from the base distribution. These routines +are readily available in most countries from RSA Laboratories. +Directions for their use are in the <a href="build.htm">Building +and Installing the Distribution</a> page.</p> +</li> + +<li> +<p>As the result of the above, the <tt>./authstuff</tt> directory, +intended as a development and testing aid for porting cryptographic +routines to exotic architectures, has been removed. Developers +should note the NTP authentication routines use the interface +defined in the <tt>rsaref2.0</tt> package available from RSA +laboratories.</p> +</li> + +<li> +<p>The enable and disable commands have a few changes in their +arguments see the <tt>ntpd</tt> <a href="confopt.htm">Configuration +Options</a> page for details. Note that the <tt>authenticate</tt> +command has been removed.</p> +</li> + +<li> +<p>The <tt>ppsclock</tt> line discipline/streams module is no +longer supported. This function is now handled by the <a href= +"driver22.htm">PPS Clock Discipline</a> driver, which uses the new +PPSAPI application program interface proposed by the IETF. Note +that the <tt>pps</tt> configuration file command has been obsoleted +by the driver. See the <a href="pps.htm">Pulse-per-second (PPS) +Signal Interfacing</a> page for further information.</p> +</li> + +<li> +<p>Several new options have been added for the <tt>ntpd</tt> +command line. For the inveterate knob twiddlers several of the more +important performance variables can be changed to fit actual or +perceived special conditions. It is possible to operate the daemon +in a one-time mode similar to <tt>ntpdate</tt>, which program is +headed for retirement. See the <a href="ntpd.htm"><tt>ntpd</tt> - +Network Time Protocol (NTP) daemon</a> page for the new +features.</p> +</li> + +<li> +<p>To help reduce the level of spurious network traffic due to +obsolete configuration files, a special control message called the +kiss-of-death packet has been implemented. If enabled and a packet +is denied service or exceeds the client limie, a compliant server +will send this message to the client. A compliant client will cease +further transmission and send a message to the system log. See the +<a href="accopt.htm">Authentication Options</a> page for further +information.</p> +</li> + +<li> +<p>An experimental filter algorithm called huff-n'-puff has been +implemented to reduce errors under conditions of severe assymetric +delays characteristic of <tt>ppp</tt> connections with telephone +modems and downloading or uploading considerable traffic. See the +<a href="ntpd.htm">ntpd - Network Time Protocol (NTP) daemon</a> +page for further information.</p> +</li> +</ol> + +<h4>Caveats</h4> + +<p>This release has been compiled and tested on several systems, +including SunOS 4.1.3, Solaris 2.5.1-2.8, Alpha 4.0, Ultrix 4.4, +Linux, FreeBSD and HP-UX 10.02. It has been compiled and tested on +Windows NT, but not yet on any other Windows version or for VMS. We +are relying on the NTP volunteer corps to do that. Known problems +are summarized below:</p> + +<ol> +<li> +<p>The latest NTPv4 <tt>ntpdc</tt> does not work with previous +versions of <tt>ntpd</tt> and previous versions of <tt>ntpdc</tt> +do not work with latest <tt>ntpd</tt>. This situation is +regrettable and may be fixed in future; however, it is necessary in +order for the autokey function to retrieve canonical names and +certificates from directory services such as Secure DNS.</p> +</li> + +<li> +<p>The precision time support in stock Solaris 2.6 has bugs that +were fixed in 2.7. A patch is available that fixes the 2.6 bugs. +The 2.6 kernel discipline has been disabled by default. For +testing, the kernel can be enabled using the <tt>enable kernel</tt> +command either in the configuration file or via <tt>ntpdc</tt>.</p> +</li> + +<li> +<p>The HTML documentation has been partially updated. However, most +of the NTPv3 documentation continues to apply to NTPv4. Until the +update happens, what you see is what you get. We are always happy +to accept comments, corrections and bug reports. However, we are +most thrilled upon receipt of patches to fix the dang bugs.</p> +</li> +</ol> + +<hr> +<a href="index.htm"><img align="left" src="pic/home.gif" alt= +"gif"></a> + +<address><a href="mailto:mills@udel.edu">David L. Mills +<mills@udel.edu></a></address> +</body> +</html> + |
