Name

pfopen − open a packet filter file

Syntax

pfopen(ifname, flags)
char *ifname;
int flags;

Description

The packet filter (see packetfilter() ) 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, “de0”, “qe2”) 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() system call.

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

Diagnostics

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.

If there are a lot of packet filter applications in use, the pfopen routine might take a while.

See Also

open(2), packetfilter(4)
The Packet Filter:  An Efficient Mechanism for User Level Network Code