pfopen - Open a packet filter file
char *ifname; int flags;
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).
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.
Files: bpf(7), packetfilter(7) delim off