This page controls the SNTP server portion of Net Time Server & Client operation. In the page, you can change many of the settings that affect the SNTP server. To access this "Server - SNTP" page, select the "Server" item then select the "SNTP" item from the tree menu on the lef side of the "Main window".
The section allows you to specify a number of settings for the SNTP server. Unless expressly specified, including unicast/manycast and broadcast/multicast mode.
Specifies the IP address that the SNTP server will use it to listen for the NTP/SNTP unicast request packet, and to send the NTP/SNTP unicast reply packet and NTP/SNTP broadcast packet. Using the "0.0.0.0" binding IP address will bind to both of your network interface cards.
Specifies the number of local UDP port that the SNTP server will use it to listen for the SNTP unicast/manycast request packet, and to send the NTP/SNTP unicast/manycast reply packet and NTP/SNTP broadcast/multicast packet. By default, it's port 123.
Specifies the version number that is used by the SNTP server, typical values include "Version 3 (RFC-1769)", "Version 4 (RFC-2030)" and "Version 4 (RFC-4330)". The SNTP server accept all clients that their version is earlier than or equal to this version value. See also the table below about the server version and client version.
| Client | |||
|---|---|---|---|
| Version 3 | Version 4 | ||
| Server | Version 3 (RFC-1769) | Work under Version 3 (RFC-1769) | Don't work |
| Version 4 (RFC-2030) | Work under Version 3 (RFC-1769) | Work under Version 4 (RFC-2030) | |
| Version 4 (RFC-4330) | Work under Version 3 (RFC-1769) | Work under Version 4 (RFC-4330) | |
If the server and client work under version 4 (RFC-4330), the KoD messages below are supported. The SNTP server use them to tell a client to stop making requests.
| KoD message | Meaning |
|---|---|
| INIT | The server is initializating or the server clcok has not yet synchronized for the first time with an external time source. |
| STEP | The server clock has been changed and it has not yet synchronized with an external time source. |
| DENY | The client has been blocked due to the permission settings. |
| RATE | The client has been provisionally blocked due to the rate limitation. |
| RSTR | The version field is invalid in the request packet. |
| EXTM | Some time stamps are invalid in the request packet. |
| EXMD | The mode field is invalid in the request packet. |
Specifies the local clock precision for the server to generate the NTP/SNTP datagram. It's about 50 milliseconds (-4: 64 milliseconds) for Windows 95/98/Me, and it's about 10 milliseconds (-6: 16 milliseconds) for Windows NT4/2000/XP/2003/Vista.
Specifies the level of accuracy of this server clock. The NTP/SNTP specification allows a number from 1 to 15. If the stratum field is 1, indicating a primary server and most accurate (e.g., synchronized by radio clock). If the stratum field is 2 to 15, indicating a secondary server (synchronized by NTP or SNTP).
Specifies the maximum interval between successive reply packets in seconds. According to the performance of your computer, the value range is from 0 (1 second) to 8 (256 seconds).
If the stratum field is set to 1 (Primary server), a four-characters code should be specified in this field in order to identify the external reference source. You can use one of the predefined codes that they are listed in following table, or customizate your own Reference ID. (For secondary servers, the Reference ID is the IP address of the synchronization source).
| Reference ID | Meaning |
|---|---|
| LOCL | Uncalibrated local clock |
| CESM | Calibrated Cesium clock |
| RBDM | Calibrated Rubidium clock |
| PPS | Calibrated quartz clock or other pulse-per-second source |
| IRIG | Inter-Range Instrumentation Group |
| ACTS | NIST telephone modem service |
| USNO | USNO telephone modem service |
| PTB | PTB (Germany) telephone modem service |
| TDF | Allouis (France) Radio 164 kHz |
| DCF | Mainflingen (Germany) Radio 77.5 kHz |
| MSF | Rugby (UK) Radio 60 kHz |
| WWV | Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz |
| WWVB | Boulder (US) Radio 60 kHz |
| WWVH | Kauai Hawaii (US) Radio 2.5, 5, 10, 15 MHz |
| CHU | Ottawa (Canada) Radio 3330, 7335, 14670 kHz |
| LORC | LORAN-C radionavigation system |
| OMEG | OMEGA radionavigation system |
| GPS | Global Positioning Service |
| GOES | Geostationary Orbit Environment Satellite |
Specifies the maximum error due to the clock frequency tolerance in second. The values range is from zero to several hundred milliseconds. By default, the value is zero.
Checking the box causes the SNTP server to assume that the local system clock has been synchronized with an external time source by the client portion of the Net Time Server & Client.
If your SNTP server will not synchronize with an external time source and it is in an isolated LAN, please check the box.
In general, the SNTP server will respond to NTP/SNTP time requests with a real reference time stamp if it has set its own time using an external time source, otherwise the SNTP server will use zero as the reference time stamp. If the box is checked, the SNTP server will use the server's current time and date as the reference time stamp in NTP/SNTP reply packet.
If your SNTP server will not synchronize with an external time source and it is in an isolated LAN, please check the box.
In general, if the server and client work under version 3 or version 4 (RFC-2030), all invalid NTP/SNTP request packets will be discarded. If the server and client work under version 4 (RFC-4330), the server will reply a KoD meessage for every invlaid request packet. Checking the box causes the SNTP server to discard all invalid request packets from client even if them work under vresion 4 (RFC-4330).
Check the box to discard all request packets from all NTP/SNTP unicast and manycast clients when the local system clcok of the SNTP server is unsynchronized with an external time source by the client portion of the Net Time Server & Client. It avoids the inaccuracy NTP/SNTP unicast/manycast reply packet that is sent from the Time server.
Checking the box to discard all request packets from NTP/SNTP unicast and manycast clients that they have been blocked by the server due to the rate limiation or due to the permission settings in the "Unicast/Manycast SNTP server Permission" dialog box.
Checking the box allows the SNTP server to listen for NTP/SNTP unicast or manycast request packet from NTP/SNTP clients, and then to send the NTP/SNTP reply packet to the client that made request. The NTP/SNTP reply packet will be used to synchronize the local system clock of client that made request.
Click on the button to open the "Unicast/Manycast SNTP server permission" dialog box. You can use the dialog box to manage a list of IP/Mask pairs, the unicast/manycast SNTP server use the list for access control, so that only those clients known to be trusted will be accepted. See also the "Unicast/Manycast SNTP server permission".
Checking the box allows the SNTP server listen for NTP/SNTP maycast request packets.
Specifies the multicast IP address that the SNTP server will use it to listen for the NTP/SNTP manycast request packet.
Checking the box allows the SNTP server to limit the rate of request from any NTP/SNTP client using the unicast mode or using the manycast mode. See also the "Rate limitation list" in the "Server" and see also the "Limiter period" below .
Specifies the minimum time interval that can be accepted by the SNTP server between two successive request from the same client. If the interval of sending time is less than the limiter period between every request packet from the same client, for first request packet, the SNTP server will exactly send an NTP/SNTP reply packet, for every later request packet from the client, according to the client version and SNTP server settings in this page, the SNTP server will discarded it or reply a KoD message "RATE" until the time interval reach to the limiter period between the sending the first exactly reply and receiveing this request packet, In other words, until the client is removed from "Rate limitation list" in the "Server" page. See also the "Server".
The RATE message will be sent only if the client is version 4, the "Version" field is set to "Version 4 (RFC-4330)" and the "Ignore request if client is blocked" box is checked off in this page, othewise the request packets will be discarded.
Checking the box to enable the client in LAN using the "Find time server in LAN" window to find this SNTP unicast server and this SNTP manycast server if they are running.
Checking the box allows the SNTP server to periodically send the broadcast packet or the multicast packet. After the packet is received by the NTP/SNTP client, it will be used to synchronize the local system clock of the NTP/SNTP client.
Specifies the broadcast address or the multicast group address. The SNTP server will send the broadcast packet or the multicast packet to it. By default, it's "255.255.255.255".
Specifies the number of port that the NTP/SNTP broadcast or multicast packet will be sent to. By default, it's port 123.
Specifies the interval of time in seconds between two broadcast transmissions or multicast transmissions. It controls the frequency of broadcast or multicast transmissions.
Specifies the number of routers a NTP/SNTP multicast packet can pass through before the packet can be discarded. Each router that processes the multicast packet decrements the TTL (Time to Live) field and discards the packet if the value reaches 0, so only multicast clients in scope will receive multicast packet.
Specifies the IP address that the SNTP server will use it to send the NTP/SNTP mulitcast packet.
With this button you will accept and save current configuration.
With this button you will cancel current configuration and rollback to previous one.