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pfopen(3)
NAME
  pfopen - Open a packet filter file

SYNOPSIS
  pfopen(ifname, flags)

  char *ifname; int flags;

DESCRIPTION
  The packet filter (see packetfilter(7)) provides raw access to Ethernets
  and similar network data link layers.	 The routine pfopen is used to open a
  packet filter file descriptor.  The routine hides various details about the
  way packet filter files are opened and named.

  The ifname argument is a pointer to a null-terminated string containing the
  name of the interface for which the application is opening the packet
  filter.  This name may be the name of an actual interface on the system
  (for example, ln0) or it may be a pseudo-interface name of the form pfn,
  used to specify the nth interface attached to the system.  For example, pf0
  specifies the first such interface.  If ifname is NULL, the default
  interface (pf0) is used.

  The flags argument has the same meaning as the corresponding argument to
  the open(2) system call.

  The file descriptor returned by pfopen is otherwise identical to one
  returned by open(2).

ERRORS
  The pfopen routine returns a negative integer if the file could not be
  opened.  This may be because of resource limitations, or because the
  specified interface does not exist.

RELATED INFORMATION
  Commands: open(2)

  Files: bpf(7), packetfilter(7)