IF_NAMETOINDEX(3)

NAME
if_nametoindex, if_indextoname - mappings between network interface names and indexes

LIBRARY
Standard C library (libc, -lc)

SYNOPSIS
#include <net/if.h>

unsigned int if_nametoindex(const char *ifname);
char *if_indextoname(unsigned int ifindex, char *ifname);

DESCRIPTION
The if_nametoindex() function returns the index of the network interface corresponding to the name ifname.

The if_indextoname() function returns the name of the network interface corresponding to the interface index ifindex. The name is placed in the buffer pointed to by ifname. The buffer must allow for the storage of at least IF_NAMESIZE bytes.

RETURN VALUE
On success, if_nametoindex() returns the index number of the network interface; on error, 0 is returned and errno is set to indicate the error.

On success, if_indextoname() returns ifname; on error, NULL is returned and errno is set to indicate the error.

ERRORS
if_nametoindex() may fail and set errno if:

ENODEV
    No interface found with given name.

if_indextoname() may fail and set errno if:

ENXIO
    No interface found for the index.

if_nametoindex() and if_indextoname() may also fail for any of the errors specified for socket(2) or ioctl(2).

ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value
 | Thread safety | MT-Safe

STANDARDS
POSIX.1-2001, POSIX.1-2008, RFC 3493.

This function first appeared in BSDi.

SEE ALSO
getifaddrs(3), if_nameindex(3), ifconfig(8)