Note: On WinXP the 'Windows Time' service must be stopped for NTP packets to be passed up the stack and visible to Wireshark. Mills' NTP site Network Time Synchronization Research Project

Ntp.org Home of the Network Time Protocol RFC 1305 Network Time Protocol (Version 3) Specification, Implementation and Analysis The following are all valid display filter expressions: tcp.port 80 and ip.src 192.168.2.1 not llc http and frame 100-199 contains 'wireshark' ( 0xbad & 0.0.0.0.0.1) ip Remember that whenever a protocol or field name occurs in an expression, the 'exists' operator is implicitly called. RFC 1119 Network Time Protocol (Version 2) Specification and Implementation RFC 1059 Network Time Protocol (Version 1) Specification and Implementation RFC 5905 Network Time Protocol Version 4: Protocol and Algorithms Specification.On many systems, you can say 'udp port ntp' rather than 'udp port 123'. However, you can filter on the well known NTP UDP port 123.Ĭapture only the NTP based traffic: udp port 123 You cannot directly filter NTP protocols while capturing. Show only the NTP based traffic: ntp Capture Filter SampleCaptures/NTP_with_MD5_key_foobar.pcap (MD5 encryption key: 'foobar')Ī complete list of NTP display filter fields can be found in the display filter reference You can use editcap to delete duplicate packets (from 'editcap -h'): Duplicate packet removal: -d remove packet if duplicate (window 5). There are no NTP related preference settings. If you want to filter (delete) duplicate frames, the ip.id is not sufficient as the same ip.id can be used for different IP addresses without being a duplicate. XXX - Add example traffic here (as plain text or Wireshark screenshot).

The well known UDP port for NTP traffic is 123.

UDP: Typically, NTP uses UDP as its transport protocol.

The Wikipedia article has a relevant writeup of the protocol. A lot of intricate details are involved, which are described in the relevant research project pages History Adjusting the clock is not instantaneously, but smoothed over time towards the reference time sources selected. The NTP client asks the NTP server about the current time, and then will adjust it's internal clock to that value. The NTP server will (hopefully) have the precise time (probably directly from an atomic clock). In short, the filters are here: ip.addr 10.0.0.1 tcp or dns tcp.port 443 (arp or icmp or dns) follow tcp stream tcp contains facebook 200. NTP is used to synchronize the clock of a network client with a server.

Wireshark filter by ip wildcard