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100 lines
3.4 KiB
Plaintext
100 lines
3.4 KiB
Plaintext
.\" @(#) $Header: /tcpdump/master/libpcap/pcap_stats.3pcap,v 1.3 2008-04-06 02:53:22 guy Exp $
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.\"
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.\" Copyright (c) 1994, 1996, 1997
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that: (1) source code distributions
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.\" retain the above copyright notice and this paragraph in its entirety, (2)
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.\" distributions including binary code include the above copyright notice and
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.\" this paragraph in its entirety in the documentation or other materials
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.\" provided with the distribution, and (3) all advertising materials mentioning
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.\" features or use of this software display the following acknowledgement:
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.\" ``This product includes software developed by the University of California,
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.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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.\" the University nor the names of its contributors may be used to endorse
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.\" or promote products derived from this software without specific prior
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.\" written permission.
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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.\"
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.TH PCAP_STATS 3PCAP "7 September 2009"
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.SH NAME
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pcap_stats \- get capture statistics
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.SH SYNOPSIS
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.nf
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.ft B
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#include <pcap/pcap.h>
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.ft
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.LP
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.ft B
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int pcap_stats(pcap_t *p, struct pcap_stat *ps);
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.ft
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.fi
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.SH DESCRIPTION
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.B pcap_stats()
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fills in the
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.B struct pcap_stat
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pointed to by its second argument. The values represent
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packet statistics from the start of the run to the time of the call.
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.PP
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.B pcap_stats()
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is supported only on live captures, not on ``savefiles''; no statistics
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are stored in ``savefiles'', so no statistics are available when reading
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from a ``savefile''.
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.PP
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A
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.B struct pcap_stat
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has the following members:
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.RS
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.TP
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.B ps_recv
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number of packets received;
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.TP
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.B ps_drop
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number of packets dropped because there was no room in the operating
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system's buffer when they arrived, because packets weren't being read
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fast enough;
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.TP
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.B ps_ifdrop
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number of packets dropped by the network interface or its driver.
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.RE
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.PP
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The statistics do not behave the same way on all platforms.
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.B ps_recv
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might count packets whether they passed any filter set with
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.BR pcap_setfilter (3PCAP)
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or not, or it might count only packets that pass the filter.
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It also might, or might not, count packets dropped because there was no
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room in the operating system's buffer when they arrived.
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.B ps_drop
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is not available on all platforms; it is zero on platforms where it's
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not available. If packet filtering is done in libpcap, rather than in
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the operating system, it would count packets that don't pass the filter.
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Both
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.B ps_recv
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and
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.B ps_drop
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might, or might not, count packets not yet read from the operating
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system and thus not yet seen by the application.
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.B ps_ifdrop
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might, or might not, be implemented; if it's zero, that might mean that
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no packets were dropped by the interface, or it might mean that the
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statistic is unavailable, so it should not be treated as an indication
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that the interface did not drop any packets.
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.SH RETURN VALUE
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.B pcap_stats()
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returns 0 on success and returns \-1 if there is an error or if
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.I p
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doesn't support packet statistics.
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If \-1 is returned,
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.B pcap_geterr()
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or
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.B pcap_perror()
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may be called with
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.I p
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as an argument to fetch or display the error text.
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.SH SEE ALSO
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pcap(3PCAP), pcap_geterr(3PCAP)
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