NTP, Network Time Protocol |
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Description | Glossary | RFCs | Publications | Obsolete RFCs |
Protocol suite: | TCP/IP. |
Protocol type: | Application layer time protocol. |
Multicast addresses: | 224.0.1.1. |
Related protocols: | SNTP, Simple Network Time Protocol. |
Port: | 123 (UDP). |
MIME subtype: | |
SNMP MIBs: | iso.org.dod.internet.mgmt.mib-2.ntpSnmp (1.3.6.1.2.1.197). |
Working groups: | ntp, Network Time Protocol. |
Links: | www.ntp.org www.pool.ntp.org |
NTP version 0
NTP version 1
NTP version 3
NTP version 4
This version adds support for the Autokey security protocol.
MAC header | IP header | UDP header | NTP message |
NTP version 3 message
ADDR | +0 | +1 | +2 | +3 | ||||||||||||||||||||||||||||
ADDR | 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+0 ARDUINO |
LI | Version | Mode | Stratum | Poll interval | Precision | ||||||||||||||||||||||||||
3 | 0 | 7 | 0 | 6 | 0xEC | |||||||||||||||||||||||||||
+4 | Root delay | |||||||||||||||||||||||||||||||
+8 | Root dispersion | |||||||||||||||||||||||||||||||
+12 | Reference clock identifier | |||||||||||||||||||||||||||||||
+16 +20 |
Reference
timestamp & fraction (64bit) |
|||||||||||||||||||||||||||||||
+24 +28 |
Originate
timestamp & fraction (64bit) |
|||||||||||||||||||||||||||||||
+32 +36 |
Receive
timestamp & ffraction (64bit) |
|||||||||||||||||||||||||||||||
+40 +44 |
Transmit
timestamp & fraction (64bit) |
|||||||||||||||||||||||||||||||
+48 in arduino this no exist.. |
Authenticator
12byte - 96bit - |
LI, Leap
Indicator.
2 bits.
This field is used to warn of an impending leap second.
LI | Description |
---|---|
0 | No warning. |
1 | Last minute has 61 seconds. |
2 | Last minute has 59 seconds. |
3 | Alarm condition, clock not synchronized. |
Version.
3 bits.
NTP version number.
Mode. 3 bits.
Mode | Description |
---|---|
0 | reserved. |
1 | Symmetric active. |
2 | Symmetric passive. |
3 | Client. |
4 | Server. |
5 | Broadcast. |
6 | NTP control message. |
7 | private use. |
Stratum.
8 bits.
Stratum level of the local clock.
Stratum | Description |
---|---|
0 | unspecified. |
1 | Primary reference. |
2 - 255 |
Secondary reference. |
Poll interval.
8 bits, signed.
The maximum interval between messages in seconds to the nearest power
of two.
Precision.
8 bits, signed.
Precision of the local clock in seconds to the nearest power of two.
Root delay.
32 bits, signed fixed point.
The total roundtrip delay to the primary reference source, in seconds
with the fraction point between bits 15 and 16.
Positive and negative values are valid.
Root dispersion.
32 bits, signed fixed point.
The maximum error relative to the primary reference source in seconds
with the fraction point between bits 15 and 16.
Only positive values greater than zero are valid.
Reference
clock identifier.
32 bits.
Used to identify the particular reference clock.
In the case of stratum 2 and greater (secondary reference) this is the IPv4 address of the primary reference host.
In the case of stratum 0 (unspecified) or stratum 1 (primary reference), this is a four byte, left-justified, zero padded ASCII string. While not enumerated as part of the NTP specification, the following are suggested ASCII identifiers:
Stratum | Identifier | Description |
---|---|---|
0 | "DCN" | DCN routing protocol. |
0 | "NIST" | NIST public modem. |
0 | "TSP" | TSP time protocol. |
0 | "DTS" | Digital Time Service. |
1 | "ATOM" | Atomic clock (calibrated). |
1 | "VLF" | VLF radio. |
1 | callsign | Generic radio. |
1 | "LORC" | LORAN-C. |
1 | "GOES" | GOES UHF environment satellite. |
1 | "GPS" | GPS UHF positioning satellite. |
Reference
timestamp.
64 bits.
The local time at which the local clock was last set or corrected.
Originate
timestamp.
64 bits.
The local time when the client sent the request.
Receive
timestamp.
64 bits.
The local time when the request was received by the server.
Transmit
timestamp.
64 bits.
The local time when the reply was sent from the server.
Authenticator. 0 or 96 bits.
Year | NTP+TZ(+1h) | DST Start (Clock Forward) | NTP+TZ(+1h) | DST End (Clock Backward) |
---|---|---|---|---|
2010 | 1269741600 | vasárnap, március 28., 02:00 | 1288490400 | vasárnap, október 31., 03:00 |
2011 | 1301191200 | vasárnap, március 27., 02:00 | 1319940000 | vasárnap, október 30., 03:00 |
2012 | 1332640800 | vasárnap, március 25., 02:00 | 1351389600 | vasárnap, október 28., 03:00 |
2013 | 1364695200 | vasárnap, március 31., 02:00 | 1382839200 | vasárnap, október 27., 03:00 |
2014 | 1396144800 | vasárnap, március 30., 02:00 | 1414288800 | vasárnap, október 26., 03:00 |
2015 | 1427594400 | vasárnap, március 29., 02:00 | 1445738400 | vasárnap, október 25., 03:00 |
2016 | 1459044000 | vasárnap, március 27., 02:00 | 1477792800 | vasárnap, október 30., 03:00 |
2017 | 1490493600 | vasárnap, március 26., 02:00 | 1509242400 | vasárnap, október 29., 03:00 |
2018 | 1521943200 | vasárnap, március 25., 02:00 | 1540692000 | vasárnap, október 28., 03:00 |
2019 | 1553997600 | vasárnap, március 31., 02:00 | 1572141600 | vasárnap, október 27., 03:00 |
All times are local for Budapest. Current year is highlighted. |
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