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  20 .TH PCAP_ACTIVATE 3PCAP "31 July 2016"
  21 .SH NAME
  22 pcap_activate \- activate a capture handle
  23 .SH SYNOPSIS
  24 .nf
  25 .ft B
  26 #include <pcap/pcap.h>
  27 .ft
  28 .LP
  29 .ft B
  30 int pcap_activate(pcap_t *p);
  31 .ft
  32 .fi
  33 .SH DESCRIPTION
  34 .B pcap_activate()
  35 is used to activate a packet capture handle to look
  36 at packets on the network, with the options that were set on the handle
  37 being in effect.
  38 .SH RETURN VALUE
  39 .B pcap_activate()
  40 returns 0 on success without warnings, a non-zero positive value on
  41 success with warnings, and a negative value on error.
  42 A non-zero return value indicates what warning or error condition
  43 occurred.
  44 .LP
  45 The possible warning values are:
  46 .TP
  47 .B PCAP_WARNING_PROMISC_NOTSUP
  48 Promiscuous mode was requested, but the capture source doesn't support
  49 promiscuous mode.
  50 .TP
  51 .B PCAP_WARNING_TSTAMP_TYPE_NOTSUP
  52 The time stamp type specified in a previous
  53 .BR pcap_set_tstamp_type (3PCAP)
  54 call isn't supported by the capture source (the time stamp type is
  55 left as the default),
  56 .TP
  57 .B PCAP_WARNING
  58 Another warning condition occurred;
  59 .BR pcap_geterr (3PCAP)
  60 or
  61 .BR pcap_perror (3PCAP)
  62 may be called with
  63 .I p
  64 as an argument to fetch or display a message describing the warning
  65 condition.
  66 .LP
  67 The possible error values are:
  68 .TP
  69 .B PCAP_ERROR_ACTIVATED
  70 The handle has already been activated.
  71 .TP
  72 .B PCAP_ERROR_NO_SUCH_DEVICE
  73 The capture source specified when the handle was created doesn't
  74 exist.
  75 .TP
  76 .B PCAP_ERROR_PERM_DENIED
  77 The process doesn't have permission to open the capture source.
  78 .TP
  79 .B PCAP_ERROR_PROMISC_PERM_DENIED
  80 The process has permission to open the capture source but doesn't
  81 have permission to put it into promiscuous mode.
  82 .TP
  83 .B PCAP_ERROR_RFMON_NOTSUP
  84 Monitor mode was specified but the capture source doesn't support
  85 monitor mode.
  86 .TP
  87 .B PCAP_ERROR_IFACE_NOT_UP
  88 The capture source device is not up.
  89 .TP
  90 .B PCAP_ERROR
  91 Another error occurred.
  92 .B pcap_geterr()
  93 or
  94 .B pcap_perror()
  95 may be called with
  96 .I p
  97 as an argument to fetch or display a message describing the error.
  98 .LP
  99 If
 100 .BR PCAP_WARNING_PROMISC_NOTSUP ,
 101 .BR PCAP_ERROR_NO_SUCH_DEVICE ,
 102 or
 103 .B PCAP_ERROR_PERM_DENIED
 104 is returned,
 105 .B pcap_geterr()
 106 or
 107 .B pcap_perror()
 108 may be called with
 109 .I p
 110 as an argument to fetch or display an message giving additional details
 111 about the problem that might be useful for debugging the problem if it's
 112 unexpected.
 113 .LP
 114 Additional warning and error codes may be added in the future; a program
 115 should check for positive, negative, and zero return codes, and treat
 116 all positive return codes as warnings and all negative return
 117 codes as errors.
 118 .BR pcap_statustostr (3PCAP)
 119 can be called, with a warning or error code as an argument, to fetch a
 120 message describing the warning or error code.
 121 .SH SEE ALSO
 122 .BR pcap (3PCAP)