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PCAP(3)                    Library Functions Manual                    PCAP(3)



NAME
       pcap - Packet Capture library

SYNOPSIS
       #include <pcap/pcap.h>


DESCRIPTION
       The Packet Capture library provides a high level interface to packet
       capture systems. All packets on the network, even those destined for
       other hosts, are accessible through this mechanism.  It also supports
       saving captured packets to a ``savefile'', and reading packets from a
       ``savefile''.

   Initializing
       pcap_init() initializes the library.  It takes an argument giving
       options; currently, the options are:

       PCAP_CHAR_ENC_LOCAL
              Treat all strings supplied as arguments, and return all strings
              to the caller, as being in the local character encoding.

       PCAP_CHAR_ENC_UTF_8
              Treat all strings supplied as arguments, and return all strings
              to the caller, as being in UTF-8.

       On UNIX-like systems, the local character encoding is assumed to be
       UTF-8, so no character encoding transformations are done.

       On Windows, the local character encoding is the local ANSI code page.

       If pcap_init() is called, the deprecated pcap_lookupdev() routine
       always fails, so it should not be used, and, on Windows, pcap_create()
       does not attempt to handle UTF-16LE strings.

       If pcap_init() is not called, strings are treated as being in the local
       ANSI code page on Windows, pcap_lookupdev() will succeed if there is a
       device on which to capture, and pcap_create() makes an attempt to check
       whether the string passed as an argument is a UTF-16LE string - note
       that this attempt is unsafe, as it may run past the end of the string -
       to handle pcap_lookupdev() returning a UTF-16LE string. Programs that
       don't call pcap_init() should, on Windows, call pcap_wsockinit() to
       initialize Winsock; this is not necessary if pcap_init() is called, as
       pcap_init() will initialize Winsock itself on Windows.

       Routines

              pcap_init(3)
                     initialize the library

   Opening a capture handle for reading
       To open a handle for a live capture, given the name of the network or
       other interface on which the capture should be done, call
       pcap_create(), set the appropriate options on the handle, and then
       activate it with pcap_activate().  If pcap_activate() fails, the handle
       should be closed with pcap_close().

       To obtain a list of devices that can be opened for a live capture, call
       pcap_findalldevs(); to free the list returned by pcap_findalldevs(),
       call pcap_freealldevs().  pcap_lookupdev() will return the first device
       on that list that is not a ``loopback`` network interface.

       To open a handle for a ``savefile'' from which to read packets, given
       the pathname of the ``savefile'', call pcap_open_offline(); to set up a
       handle for a ``savefile'', given a FILE * referring to a file already
       opened for reading, call pcap_fopen_offline().

       In order to get a ``fake'' pcap_t for use in routines that require a
       pcap_t as an argument, such as routines to open a ``savefile'' for
       writing and to compile a filter expression, call pcap_open_dead().

       pcap_create(), pcap_open_offline(), pcap_fopen_offline(), and
       pcap_open_dead() return a pointer to a pcap_t, which is the handle used
       for reading packets from the capture stream or the ``savefile'', and
       for finding out information about the capture stream or ``savefile''.
       To close a handle, use pcap_close().

       The options that can be set on a capture handle include

       snapshot length
              If, when capturing, you capture the entire contents of the
              packet, that requires more CPU time to copy the packet to your
              application, more disk and possibly network bandwidth to write
              the packet data to a file, and more disk space to save the
              packet.  If you don't need the entire contents of the packet -
              for example, if you are only interested in the TCP headers of
              packets - you can set the "snapshot length" for the capture to
              an appropriate value.  If the snapshot length is set to snaplen,
              and snaplen is less than the size of a packet that is captured,
              only the first snaplen bytes of that packet will be captured and
              provided as packet data.

              A snapshot length of 65535 should be sufficient, on most if not
              all networks, to capture all the data available from the packet.

              The snapshot length is set with pcap_set_snaplen().

       promiscuous mode
              On broadcast LANs such as Ethernet, if the network isn't
              switched, or if the adapter is connected to a "mirror port" on a
              switch to which all packets passing through the switch are sent,
              a network adapter receives all packets on the LAN, including
              unicast or multicast packets not sent to a network address that
              the network adapter isn't configured to recognize.

              Normally, the adapter will discard those packets; however, many
              network adapters support "promiscuous mode", which is a mode in
              which all packets, even if they are not sent to an address that
              the adapter recognizes, are provided to the host.  This is
              useful for passively capturing traffic between two or more other
              hosts for analysis.

              Note that even if an application does not set promiscuous mode,
              the adapter could well be in promiscuous mode for some other
              reason.

              For now, this doesn't work on the "any" device; if an argument
              of "any" or NULL is supplied, the setting of promiscuous mode is
              ignored.

              Promiscuous mode is set with pcap_set_promisc().

       monitor mode
              On IEEE 802.11 wireless LANs, even if an adapter is in
              promiscuous mode, it will supply to the host only frames for the
              network with which it's associated.  It might also supply only
              data frames, not management or control frames, and might not
              provide the 802.11 header or radio information pseudo-header for
              those frames.

              In "monitor mode", sometimes also called "rfmon mode" (for
              "Radio Frequency MONitor"), the adapter will supply all frames
              that it receives, with 802.11 headers, and might supply a
              pseudo-header with radio information about the frame as well.

              Note that in monitor mode the adapter might disassociate from
              the network with which it's associated, so that you will not be
              able to use any wireless networks with that adapter.  This could
              prevent accessing files on a network server, or resolving host
              names or network addresses, if you are capturing in monitor mode
              and are not connected to another network with another adapter.

              Monitor mode is set with pcap_set_rfmon(), and
              pcap_can_set_rfmon() can be used to determine whether an adapter
              can be put into monitor mode.

       packet buffer timeout
              If, when capturing, packets are delivered as soon as they
              arrive, the application capturing the packets will be woken up
              for each packet as it arrives, and might have to make one or
              more calls to the operating system to fetch each packet.

              If, instead, packets are not delivered as soon as they arrive,
              but are delivered after a short delay (called a "packet buffer
              timeout"), more than one packet can be accumulated before the
              packets are delivered, so that a single wakeup would be done for
              multiple packets, and each set of calls made to the operating
              system would supply multiple packets, rather than a single
              packet.  This reduces the per-packet CPU overhead if packets are
              arriving at a high rate, increasing the number of packets per
              second that can be captured.

              The packet buffer timeout is required so that an application
              won't wait for the operating system's capture buffer to fill up
              before packets are delivered; if packets are arriving slowly,
              that wait could take an arbitrarily long period of time.

              Not all platforms support a packet buffer timeout; on platforms
              that don't, the packet buffer timeout is ignored.  A zero value
              for the timeout, on platforms that support a packet buffer
              timeout, will cause a read to wait forever to allow enough
              packets to arrive, with no timeout.  A negative value is
              invalid; the result of setting the timeout to a negative value
              is unpredictable.

              NOTE: the packet buffer timeout cannot be used to cause calls
              that read packets to return within a limited period of time,
              because, on some platforms, the packet buffer timeout isn't
              supported, and, on other platforms, the timer doesn't start
              until at least one packet arrives.  This means that the packet
              buffer timeout should NOT be used, for example, in an
              interactive application to allow the packet capture loop to
              ``poll'' for user input periodically, as there's no guarantee
              that a call reading packets will return after the timeout
              expires even if no packets have arrived.

              The packet buffer timeout is set with pcap_set_timeout().

       immediate mode
              In immediate mode, packets are always delivered as soon as they
              arrive, with no buffering.  Immediate mode is set with
              pcap_set_immediate_mode().

       buffer size
              Packets that arrive for a capture are stored in a buffer, so
              that they do not have to be read by the application as soon as
              they arrive.  On some platforms, the buffer's size can be set; a
              size that's too small could mean that, if too many packets are
              being captured and the snapshot length doesn't limit the amount
              of data that's buffered, packets could be dropped if the buffer
              fills up before the application can read packets from it, while
              a size that's too large could use more non-pageable operating
              system memory than is necessary to prevent packets from being
              dropped.

              The buffer size is set with pcap_set_buffer_size().

       timestamp type
              On some platforms, the time stamp given to packets on live
              captures can come from different sources that can have different
              resolutions or that can have different relationships to the time
              values for the current time supplied by routines on the native
              operating system.  See pcap-tstamp(7) for a list of time stamp
              types.

              The time stamp type is set with pcap_set_tstamp_type().

       Reading packets from a network interface may require that you have
       special privileges:

       Under SunOS 3.x or 4.x with NIT or BPF:
              You must have read access to /dev/nit or /dev/bpf*.

       Under Solaris with DLPI:
              You must have read/write access to the network pseudo device,
              e.g.  /dev/le.  On at least some versions of Solaris, however,
              this is not sufficient to allow tcpdump to capture in
              promiscuous mode; on those versions of Solaris, you must be
              root, or the application capturing packets must be installed
              setuid to root, in order to capture in promiscuous mode.  Note
              that, on many (perhaps all) interfaces, if you don't capture in
              promiscuous mode, you will not see any outgoing packets, so a
              capture not done in promiscuous mode may not be very useful.

              In newer versions of Solaris, you must have been given the
              net_rawaccess privilege; this is both necessary and sufficient
              to give you access to the network pseudo-device - there is no
              need to change the privileges on that device.  A user can be
              given that privilege by, for example, adding that privilege to
              the user's defaultpriv key with the usermod(8) command.

       Under HP-UX with DLPI:
              You must be root or the application capturing packets must be
              installed setuid to root.

       Under IRIX with snoop:
              You must be root or the application capturing packets must be
              installed setuid to root.

       Under Linux:
              You must be root or the application capturing packets must be
              installed setuid to root, unless your distribution has a kernel
              that supports capability bits such as CAP_NET_RAW and code to
              allow those capability bits to be given to particular accounts
              and to cause those bits to be set on a user's initial processes
              when they log in, in which case you must have CAP_NET_RAW in
              order to capture.

       Under ULTRIX and Digital UNIX/Tru64 UNIX:
              Any user may capture network traffic.  However, no user (not
              even the super-user) can capture in promiscuous mode on an
              interface unless the super-user has enabled promiscuous-mode
              operation on that interface using pfconfig(8), and no user (not
              even the super-user) can capture unicast traffic received by or
              sent by the machine on an interface unless the super-user has
              enabled copy-all-mode operation on that interface using
              pfconfig, so useful packet capture on an interface probably
              requires that either promiscuous-mode or copy-all-mode
              operation, or both modes of operation, be enabled on that
              interface.

       Under BSD (this includes macOS):
              You must have read access to /dev/bpf* on systems that don't
              have a cloning BPF device, or to /dev/bpf on systems that do.
              On BSDs with a devfs (this includes macOS), this might involve
              more than just having somebody with super-user access setting
              the ownership or permissions on the BPF devices - it might
              involve configuring devfs to set the ownership or permissions
              every time the system is booted, if the system even supports
              that; if it doesn't support that, you might have to find some
              other way to make that happen at boot time.

       Reading a saved packet file doesn't require special privileges.

       The packets read from the handle may include a ``pseudo-header''
       containing various forms of packet meta-data, and probably includes a
       link-layer header whose contents can differ for different network
       interfaces.  To determine the format of the packets supplied by the
       handle, call pcap_datalink(); https://www.tcpdump.org/linktypes.html
       lists the values it returns and describes the packet formats that
       correspond to those values.

       Do NOT assume that the packets for a given capture or ``savefile`` will
       have any given link-layer header type, such as DLT_EN10MB for Ethernet.
       For example, the "any" device on Linux will have a link-layer header
       type of DLT_LINUX_SLL or DLT_LINUX_SLL2 even if all devices on the
       system at the time the "any" device is opened have some other data link
       type, such as DLT_EN10MB for Ethernet.

       To obtain the FILE * corresponding to a pcap_t opened for a
       ``savefile'', call pcap_file().

       Routines

              pcap_create(3)
                     get a pcap_t for live capture

              pcap_activate(3)
                     activate a pcap_t for live capture

              pcap_findalldevs(3)
                     get a list of devices that can be opened for a live
                     capture

              pcap_freealldevs(3)
                     free list of devices

              pcap_lookupdev(3)
                     get first non-loopback device on that list

              pcap_open_offline(3)
                     open a pcap_t for a ``savefile'', given a pathname

              pcap_open_offline_with_tstamp_precision(3)
                     open a pcap_t for a ``savefile'', given a pathname, and
                     specify the precision to provide for packet time stamps

              pcap_fopen_offline(3)
                     open a pcap_t for a ``savefile'', given a FILE *

              pcap_fopen_offline_with_tstamp_precision(3)
                     open a pcap_t for a ``savefile'', given a FILE *, and
                     specify the precision to provide for packet time stamps

              pcap_open_dead(3)
                     create a ``fake'' pcap_t

              pcap_close(3)
                     close a pcap_t

              pcap_set_snaplen(3)
                     set the snapshot length for a not-yet-activated pcap_t
                     for live capture

              pcap_snapshot(3)
                     get the snapshot length for a pcap_t

              pcap_set_promisc(3)
                     set promiscuous mode for a not-yet-activated pcap_t for
                     live capture

              pcap_set_protocol_linux(3)
                     set capture protocol for a not-yet-activated pcap_t for
                     live capture (Linux only)

              pcap_set_rfmon(3)
                     set monitor mode for a not-yet-activated pcap_t for live
                     capture

              pcap_can_set_rfmon(3)
                     determine whether monitor mode can be set for a pcap_t
                     for live capture

              pcap_set_timeout(3)
                     set packet buffer timeout for a not-yet-activated pcap_t
                     for live capture

              pcap_set_immediate_mode(3)
                     set immediate mode for a not-yet-activated pcap_t for
                     live capture

              pcap_set_buffer_size(3)
                     set buffer size for a not-yet-activated pcap_t for live
                     capture

              pcap_set_tstamp_type(3)
                     set time stamp type for a not-yet-activated pcap_t for
                     live capture

              pcap_list_tstamp_types(3)
                     get list of available time stamp types for a not-yet-
                     activated pcap_t for live capture

              pcap_free_tstamp_types(3)
                     free list of available time stamp types

              pcap_tstamp_type_val_to_name(3)
                     get name for a time stamp type

              pcap_tstamp_type_val_to_description(3)
                     get description for a time stamp type

              pcap_tstamp_type_name_to_val(3)
                     get time stamp type corresponding to a name

              pcap_set_tstamp_precision(3)
                     set time stamp precision for a not-yet-activated pcap_t
                     for live capture

              pcap_get_tstamp_precision(3)
                     get the time stamp precision of a pcap_t for live capture

              pcap_datalink(3)
                     get link-layer header type for a pcap_t

              pcap_file(3)
                     get the FILE * for a pcap_t opened for a ``savefile''

              pcap_is_swapped(3)
                     determine whether a ``savefile'' being read came from a
                     machine with the opposite byte order

              pcap_major_version(3)
              pcap_minor_version(3)
                     get the major and minor version of the file format
                     version for a ``savefile''

   Selecting a link-layer header type for a live capture
       Some devices may provide more than one link-layer header type.  To
       obtain a list of all link-layer header types provided by a device, call
       pcap_list_datalinks() on an activated pcap_t for the device.  To free a
       list of link-layer header types, call pcap_free_datalinks().  To set
       the link-layer header type for a device, call pcap_set_datalink().
       This should be done after the device has been activated but before any
       packets are read and before any filters are compiled or installed.

       Routines

              pcap_list_datalinks(3)
                     get a list of link-layer header types for a device

              pcap_free_datalinks(3)
                     free list of link-layer header types

              pcap_set_datalink(3)
                     set link-layer header type for a device

              pcap_datalink_val_to_name(3)
                     get name for a link-layer header type

              pcap_datalink_val_to_description(3)
              pcap_datalink_val_to_description_or_dlt(3)
                     get description for a link-layer header type

              pcap_datalink_name_to_val(3)
                     get link-layer header type corresponding to a name

   Reading packets
       Packets are read with pcap_dispatch() or pcap_loop(), which process one
       or more packets, calling a callback routine for each packet, or with
       pcap_next() or pcap_next_ex(), which return the next packet.  The
       callback for pcap_dispatch() and pcap_loop() is supplied a pointer to a
       struct pcap_pkthdr, which includes the following members:

              ts     a struct timeval containing the time when the packet was
                     captured

              caplen a bpf_u_int32 giving the number of bytes of the packet
                     that are available from the capture

              len    a bpf_u_int32 giving the length of the packet, in bytes
                     (which might be more than the number of bytes available
                     from the capture, if the length of the packet is larger
                     than the maximum number of bytes to capture).

       The callback is also supplied a const u_char pointer to the first
       caplen (as given in the struct pcap_pkthdr mentioned above) bytes of
       data from the packet.  This won't necessarily be the entire packet; to
       capture the entire packet, you will have to provide a value for snaplen
       in your call to pcap_set_snaplen() that is sufficiently large to get
       all of the packet's data - a value of 65535 should be sufficient on
       most if not all networks).  When reading from a ``savefile'', the
       snapshot length specified when the capture was performed will limit the
       amount of packet data available.

       pcap_next() is passed an argument that points to a struct pcap_pkthdr
       structure, and fills it in with the time stamp and length values for
       the packet.  It returns a const u_char to the first caplen bytes of the
       packet on success, and NULL on error.

       pcap_next_ex() is passed two pointer arguments, one of which points to
       a structpcap_pkthdr* and one of which points to a const u_char*.  It
       sets the first pointer to point to a struct pcap_pkthdr structure with
       the time stamp and length values for the packet, and sets the second
       pointer to point to the first caplen bytes of the packet.

       To force the loop in pcap_dispatch() or pcap_loop() to terminate, call
       pcap_breakloop().

       By default, when reading packets from an interface opened for a live
       capture, pcap_dispatch(), pcap_next(), and pcap_next_ex() will, if no
       packets are currently available to be read, block waiting for packets
       to become available.  On some, but not all, platforms, if a packet
       buffer timeout was specified, the wait will terminate after the packet
       buffer timeout expires; applications should be prepared for this, as it
       happens on some platforms, but should not rely on it, as it does not
       happen on other platforms.  Note that the wait might, or might not,
       terminate even if no packets are available; applications should be
       prepared for this to happen, but must not rely on it happening.

       A handle can be put into ``non-blocking mode'', so that those routines
       will, rather than blocking, return an indication that no packets are
       available to read.  Call pcap_setnonblock() to put a handle into non-
       blocking mode or to take it out of non-blocking mode; call
       pcap_getnonblock() to determine whether a handle is in non-blocking
       mode.  Note that non-blocking mode does not work correctly in Mac OS X
       10.6.

       Non-blocking mode is often combined with routines such as select(2) or
       poll(2) or other routines a platform offers to wait for any of a set of
       descriptors to be ready to read.  To obtain, for a handle, a descriptor
       that can be used in those routines, call pcap_get_selectable_fd().  If
       the routine indicates that data is available to read on the descriptor,
       an attempt should be made to read from the device.

       Not all handles have such a descriptor available;
       pcap_get_selectable_fd() will return -1 if no such descriptor is
       available.  If no such descriptor is available, this may be because the
       device must be polled periodically for packets; in that case,
       pcap_get_required_select_timeout() will return a pointer to a struct
       timeval whose value can be used as a timeout in those routines.  When
       the routine returns, an attempt should be made to read packets from the
       device.  If pcap_get_required_select_timeout() returns NULL, no such
       timeout is available, and those routines cannot be used with the
       device.

       In addition, for various reasons, one or more of those routines will
       not work properly with the descriptor; the documentation for
       pcap_get_selectable_fd() gives details.  Note that, just as an attempt
       to read packets from a pcap_t may not return any packets if the packet
       buffer timeout expires, a select(), poll(), or other such call may, if
       the packet buffer timeout expires, indicate that a descriptor is ready
       to read even if there are no packets available to read.

       Routines

              pcap_dispatch(3)
                     read a bufferful of packets from a pcap_t open for a live
                     capture or the full set of packets from a pcap_t open for
                     a ``savefile''

              pcap_loop(3)
                     read packets from a pcap_t until an interrupt or error
                     occurs

              pcap_next(3)
                     read the next packet from a pcap_t without an indication
                     whether an error occurred

              pcap_next_ex(3)
                     read the next packet from a pcap_t with an error
                     indication on an error

              pcap_breakloop(3)
                     prematurely terminate the loop in pcap_dispatch() or
                     pcap_loop()

              pcap_setnonblock(3)
                     set or clear non-blocking mode on a pcap_t

              pcap_getnonblock(3)
                     get the state of non-blocking mode for a pcap_t

              pcap_get_selectable_fd(3)
                     attempt to get a descriptor for a pcap_t that can be used
                     in calls such as select() and poll()

              pcap_get_required_select_timeout(3)
                     attempt to get a timeout required for using a pcap_t in
                     calls such as select() and poll()

   Filters
       In order to cause only certain packets to be returned when reading
       packets, a filter can be set on a handle.  For a live capture, the
       filtering will be performed in kernel mode, if possible, to avoid
       copying ``uninteresting'' packets from the kernel to user mode.

       A filter can be specified as a text string; the syntax and semantics of
       the string are as described by pcap-filter(7).  A filter string is
       compiled into a program in a pseudo-machine-language by pcap_compile()
       and the resulting program can be made a filter for a handle with
       pcap_setfilter().  The result of pcap_compile() can be freed with a
       call to pcap_freecode().  pcap_compile() may require a network mask for
       certain expressions in the filter string; pcap_lookupnet() can be used
       to find the network address and network mask for a given capture
       device.

       A compiled filter can also be applied directly to a packet that has
       been read using pcap_offline_filter().

       Routines

              pcap_compile(3)
                     compile filter expression to a pseudo-machine-language
                     code program

              pcap_freecode(3)
                     free a filter program

              pcap_setfilter(3)
                     set filter for a pcap_t

              pcap_lookupnet(3)
                     get network address and network mask for a capture device

              pcap_offline_filter(3)
                     apply a filter program to a packet

   Incoming and outgoing packets
       By default, libpcap will attempt to capture both packets sent by the
       machine and packets received by the machine.  To limit it to capturing
       only packets received by the machine or, if possible, only packets sent
       by the machine, call pcap_setdirection().

       Routines

              pcap_setdirection(3)
                     specify whether to capture incoming packets, outgoing
                     packets, or both

   Capture statistics
       To get statistics about packets received and dropped in a live capture,
       call pcap_stats().

       Routines

              pcap_stats(3)
                     get capture statistics

   Opening a handle for writing captured packets
       To open a ``savefile`` to which to write packets, given the pathname
       the ``savefile'' should have, call pcap_dump_open().  To open a
       ``savefile`` to which to write packets, given the pathname the
       ``savefile'' should have, call pcap_dump_open(); to set up a handle for
       a ``savefile'', given a FILE * referring to a file already opened for
       writing, call pcap_dump_fopen().  They each return pointers to a
       pcap_dumper_t, which is the handle used for writing packets to the
       ``savefile''.  If it succeeds, it will have created the file if it
       doesn't exist and truncated the file if it does exist.  To close a
       pcap_dumper_t, call pcap_dump_close().

       Routines

              pcap_dump_open(3)
                     open a pcap_dumper_t for a ``savefile``, given a
                     pathname, replacing any existing data

              pcap_dump_open_append(3)
                     open a pcap_dumper_t for a ``savefile``, given a
                     pathname, appending to the existing data

              pcap_dump_fopen(3)
                     open a pcap_dumper_t for a ``savefile``, given a FILE *,
                     assuming an empty file

              pcap_dump_close(3)
                     close a pcap_dumper_t

              pcap_dump_file(3)
                     get the FILE * for a pcap_dumper_t opened for a
                     ``savefile''

   Writing packets
       To write a packet to a pcap_dumper_t, call pcap_dump().  Packets
       written with pcap_dump() may be buffered, rather than being immediately
       written to the ``savefile''.  Closing the pcap_dumper_t will cause all
       buffered-but-not-yet-written packets to be written to the ``savefile''.
       To force all packets written to the pcap_dumper_t, and not yet written
       to the ``savefile'' because they're buffered by the pcap_dumper_t, to
       be written to the ``savefile'', without closing the pcap_dumper_t, call
       pcap_dump_flush().

       Routines

              pcap_dump(3)
                     write packet to a pcap_dumper_t

              pcap_dump_flush(3)
                     flush buffered packets written to a pcap_dumper_t to the
                     ``savefile''

              pcap_dump_ftell(3)
                     get current file position for a pcap_dumper_t

   Injecting packets
       If you have the required privileges, you can inject packets onto a
       network with a pcap_t for a live capture, using pcap_inject() or
       pcap_sendpacket().  (The two routines exist for compatibility with both
       OpenBSD and WinPcap/Npcap; they perform the same function, but have
       different return values.)

       Routines

              pcap_inject(3)
              pcap_sendpacket(3)
                     transmit a packet

   Reporting errors
       Some routines return error or warning status codes; to convert them to
       a string, use pcap_statustostr().

       Routines

              pcap_statustostr(3)
                     get a string for an error or warning status code

   Getting library version information
       To get a string giving version information about libpcap, call
       pcap_lib_version().

       Routines

              pcap_lib_version(3)
                     get library version string

BACKWARD COMPATIBILITY
       In versions of libpcap prior to 1.0, the pcap.h header file was not in
       a pcap directory on most platforms; if you are writing an application
       that must work on versions of libpcap prior to 1.0, include <pcap.h>,
       which will include <pcap/pcap.h> for you, rather than including
       <pcap/pcap.h>.

       pcap_create() and pcap_activate() were not available in versions of
       libpcap prior to 1.0; if you are writing an application that must work
       on versions of libpcap prior to 1.0, either use pcap_open_live() to get
       a handle for a live capture or, if you want to be able to use the
       additional capabilities offered by using pcap_create() and
       pcap_activate(), use an autoconf(1) script or some other configuration
       script to check whether the libpcap 1.0 APIs are available and use them
       only if they are.

SEE ALSO
       autoconf(1), tcpdump(1), tcpslice(1), pcap-filter(7), pfconfig(8),
       usermod(8)

AUTHORS
       The original authors of libpcap are:

       Van Jacobson, Craig Leres and Steven McCanne, all of the Lawrence
       Berkeley National Laboratory, University of California, Berkeley, CA.

       The current version is available from "The Tcpdump Group"'s Web site at

              https://www.tcpdump.org/

BUGS
       To report a security issue please send an e-mail to
       security@tcpdump.org.

       To report bugs and other problems, contribute patches, request a
       feature, provide generic feedback etc please see the file
       CONTRIBUTING.md in the libpcap source tree root.



                               9 September 2020                        PCAP(3)