NTP for Macintosh is a set of software components which synchronize the system clock of the Macintosh with other computers in a network. NTP for Macintosh is based upon the Internet standard Network Time Protocol, Version 2, as described in RFC 1119. This protocol is widely used within the TCP/IP community. The protocol features high reliability, low overhead, and can provide accuracy to 232 picoseconds. The protocol distributes time in a tree topology using clients, servers, peers, and broadcast technology.
NTP for Macintosh is implemented as a pair of Control Panel devices (containing a pair of corresponding INITs and one device driver) for the Macintosh Operating System, and optional software for AppleUs A/UX and DEC's VAX/VMS operating systems. NTP for Macintosh can use either AppleTalk (DDP), or IP (UDP), or both, as the transport protocol. These protocols are used for their extremely low overhead. The NTP upper level protocol is error resistant and is intended to work with datagram-oriented transport protocols. It can work effectively even in congested networks.
NTP for Macintosh is a suite of software and accompanying documentation. This shareware distribution contains only the NTP Client software and minimal documentation (this file). The remainder of the software is described in the executive summary, included with this distribution, and with the documentation available from the author.
Make sure that the name for the Macintosh has been set. In System 6 this is set via the Chooser in the field ``User Name.'' In System 7 this is set via the ``Sharing Setup'' Control Panel, in the ``Macintosh Name'' field.
Make sure that AppleTalk is ``Active'' in the Chooser (both System 6 and System 7).
Set the geographic location. To set the geographic location of the Macintosh for both System 6 and 7, use the Map Control Panel.
If TCP/IP will be used, make sure that MacTCP, V1.0.2 or later, is properly installed.
Delete any old versions of the NTP Client software you may have, including the preferences file. (This applies primarily to beta testers.) Restart the Macintosh if any old versions were present.
Insert the NTP for Macintosh distribution floppy into your floppy drive and double click on the floppy icon to open the disk. Drag the NTP Client icon onto your System Folder. (System 7 users will be asked if the file should be placed in the Control Panels folder, which it should.) Open the Control Panel from the Apple menu and select the NTP Client.
Select a network protocol to use. If you will be using an NTP time server over AppleTalk, make sure the ``AppleTalk'' Network Protocol button is pressed. Alternatively, if you will be using an NTP time server over an IP network, make sure the ``TCP/IP'' Network Protocol button is pressed.
Make sure the check box labeled ``Enable at StartUp'' is checked. If you would like to see the startup icon for the NTP Client when the Macintosh is booted, check the button labeled ``Show icon at StartUp.''
Configure the software for the local Daylight Savings Time policy. Click on the button labeled ``DST Settings...'' to bring up the first of three dialogs. In the first dialog, if your locale does not observe Daylight Savings Time, click on the ``is not'' button and dismiss the dialog by clicking on the ``OK'' button. If your locale does observe Daylight Savings Time, click on the ``is'' button; adjust the hours:minutes:seconds offset to the correct value by clicking on a part and adjusting that part up or down using the arrows to the right. (The correct value for the United States is 1:00:00.) When done, click on ``More...'' Now configure the software for the starting and ending dates for Daylight Savings Time. By default, the correct values for the United States are shown. If this is correct, click on ``More...'' in the second dialog, and ``OK'' in the third dialog. (Note that it is important for users in areas which support Daylight Savings Time to go through all three dialogs and verify the configuration once.)
Configure the software for a time server. If you are setting up an NTP Client to receive broadcast messages only (i.e., do not directly poll a server), skip this paragraph and go on to the next. Otherwise, click on the ``Servers...'' button. If using AppleTalk, servers in the current zone are shown. All zones in the AppleTalk internetwork are available through the popup menu. Select a zone and server by either double clicking on the server or pressing the ``Select'' button. If using MacTCP, hosts in the Hosts file (of your System Folder) are shown. If no hosts are displayed, edit the Hosts file to contain the name and address of the server you want to use. In the Servers dialog, select an IP server by either double clicking on the host name or pressing the ``Select'' button. When finished, click on the ``Done'' button. If you are unsure where the NTP server(s) is(are) in your network or need help editing the Hosts file, please contact your local network administrator.
If your installation uses broadcast NTP services (either IP or AppleTalk) click on the ``Accept Broadcasts'' check box to permit receipt of these packets.
After the NTP Client has been configured correctly, close the Client Control Panel. Restart your Macintosh by selecting the ``Restart'' item from the ``Special'' menu of the Finder. After the machine has restarted, you can watch the progress of the NTP Client from the Control Panel. If the software is correctly configured and communications are established, the Macintosh should begin to synchronize with the server in about four minutes.
Microsoft Mail and DAL won't play together. So what has this got to do with NTP for Macintosh? Well, the interaction is so violent that NTP for Macintosh is prevented from running. Try running either Microsoft Mail or DAL, but not both. NTP for Macintosh may be used with either.
When booting a machine that has the Microsoft Mail Server installed, and holding down the ``M'' key to temporarily disable loading of the Mail Server, NTP Client will also fail to load. There is no currently known workaround.
CE Software's CEToolbox system extension must load after the NTP Client or a system error (crash) will result. CEToolbox is part of QuickMail, QuickKeys, and other products from CE Software. To resolve the conflict, put a ~ in front of the CEToolbox file name and any other software which uses it such as QuickInit. For example, these files should be renamed ~CEToolbox and ~QuickInit, respectively. System 7 users should then move the renamed files to the System Folder. This will force the CE software to load after NTP Client. CE Software has been notified of the problem (June 30, 1993) and has yet to respond.
Users of Aldus' Date Book Pro (at least version 2.0 and later) may notice an incompatibility when NTP Client loads after Date Book Pro. (This appears to be similar to the problem mentioned with CEToolbox, above.) The workaround is to load NTP Client first either by renaming one of the products (for System 6 users) or by moving the Date Book Pro Extension to the System Folder (for System 7 users).
In order for the broadcast mechanism of AppleTalk to work, a fixed socket must be used. This implementation uses socket 123 (the same as the UDP port number) which is in the statically assigned, unrestricted experimental use range. This service is valuable enough that it is (in the author's opinion) worthwhile to use a fixed socket and hope that Apple will allocate a fixed socket for this purpose in the future. However, for the present, if you have any applications that make use of this socket or others in the reserved experimental range, you will experience difficulty. (The author is only familiar with one commercial application that uses these sockets: Timbuktu from Farallon. You can prevent Timbuktu from interfering with the NTP Client by disabling the use of socket 123 in Timbuktu. See Appendix B of the Timbuktu manual for further details.)
The NTP Client is prevented from accessing any of the known Internet stratum 0 and 1 servers. The Macintosh is simply not accurate enough to deserve this benefit. This is an intentional restriction.
The NTP Client must load after MacTCP during the boot sequence if IP protocols are going to be used.
The NTP Server software for the Macintosh, A/UX, and VAX/VMS operating systems is available at a modest price directly from the author.
For more details, contact the author at:
John Dundas
P.O. Box 50784
Pasadena, CA 91115-0784
e-mail: dundas@netcom.com