Lines Matching full:time
24 pcap-tstamp \- packet time stamps in libpcap
26 When capturing traffic, each packet is given a time stamp representing,
27 for incoming packets, the arrival time of the packet and, for outgoing
28 packets, the transmission time of the packet. This time is an
29 approximation of the arrival or transmission time. If it is supplied by
32 arrival or transmission time:
34 if the time stamp is applied to the packet when the networking stack
37 networking device driver to poll for packets, and the time stamp might
40 between the time when the last bit of the packet is received by the
41 capture device and when the networking stack time-stamps the packet;
43 the timer used to generate the time stamps might have low resolution,
50 adjusted upwards or downwards over time and the timer might not be able
53 the host operating system's clock might be adjusted over time to match a
54 time standard to which the host is being synchronized, which might be
59 running at different speeds, or might not have time counters all
60 synchronized, so packets time-stamped by different cores might not have
61 consistent time stamps;
63 some time sources, such as those that supply POSIX "seconds since the
64 Epoch" time, do not count leap seconds, meaning that the seconds
67 of the time stamp might not be incremented for a leap second, so that
68 the fraction-of-a-second part of the time stamp might roll over past
72 For these reasons, time differences between packet time stamps will not
73 necessarily accurately reflect the time differences between the receipt
76 In addition, packets time-stamped by different cores might be
77 time-stamped in one order and added to the queue of packets for libpcap
78 to read in another order, so time stamps might not be monotonically
81 Some capture devices on some platforms can provide time stamps for
82 packets; those time stamps are usually high-resolution time stamps, and
84 packet arrives, and are thus more accurate than time stamps provided by
85 the host operating system. Those time stamps might not, however, be
87 example, the time stamp of a packet might not correspond to the time
90 the issues listed above with time stamps supplied by the host operating
91 system may also apply to time stamps supplied by the capture device.
94 might allow different types of time stamp to be used. The
100 a list of time stamp types supported by the capture device for that
102 The list might be empty, in which case no choice of time stamp type is
109 call to specify the type of time stamp to be used on the device.
110 The time stamp types are listed here; the first value is the
119 Time stamp provided by the host on which the capture is being done. The
120 precision of this time stamp is unspecified; it might or might not be
124 Time stamp provided by the host on which the capture is being done.
125 This is a low-precision time stamp, synchronized with the host operating
129 Time stamp provided by the host on which the capture is being done.
130 This is a high-precision time stamp, synchronized with the host
135 Time stamp provided by the host on which the capture is being done.
136 This is a high-precision time stamp, not synchronized with the host
141 Time stamp provided by the network adapter on which the capture is being
142 done. This is a high-precision time stamp, synchronized with the host
146 Time stamp provided by the network adapter on which the capture is being
147 done. This is a high-precision time stamp; it is not synchronized with
151 Time stamps synchronized with the system clock can go backwards, as the
154 accurate time, because the other clock isn't keeping accurate time, or
157 Host-provided time stamps generally correspond to the time when the
158 time-stamping code sees the packet; this could be some unknown amount of
159 time after the first or last bit of the packet is received by the
164 time stamps are supplied as seconds since January 1, 1970, 00:00:00 UTC,
166 time stamps are available from the capture device or in the savefile.
167 If, when reading a savefile, the time stamps in the file have a higher
177 call to specify the resolution of the time stamps to get for the device.
178 If the hardware or software cannot supply a higher-resolution time
181 call will fail, and the time stamps supplied after the
189 routines can be used to specify the resolution of time stamps to be read
190 from the file; if the time stamps in the file have a lower resolution,
191 the fraction-of-a-second portion of the time stamps will be scaled to
196 routine returns the resolution of time stamps that will be supplied;
198 the time stamp supplied by the hardware or operating system and, when
199 reading a savefile, this does not indicate the actual precision of time