if_nameindex man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

if_nameindex — return all network interface names and indexes


#include <net/if.h>

struct if_nameindex *if_nameindex(void);


The if_nameindex() function shall return an array of if_nameindex structures, one structure per interface. The end of the array is indicated by a structure with an if_index field of zero and an if_name field of NULL.

Applications should call if_freenameindex() to release the memory that may be dynamically allocated by this function, after they have finished using it.

Return Value

An array of structures identifying local interfaces. A null pointer is returned upon an error, with errno set to indicate the error.


The if_nameindex() function may fail if:

Insufficient resources are available to complete the function.

The following sections are informative.

See Also

getsockopt(), if_freenameindex(), if_indextoname(), if_nametoindex(), setsockopt()

The Base Definitions volume of POSIX.1‐2008, <net_if.h>


2013 IEEE/The Open Group POSIX Programmer's Manual