if_nametoindex() — Map a network interface name to its corresponding index

Standards

Format

#define _OPEN_SYS_SOCK_IPV6
#include <net/if.h>

unsigned int if_nametoindex(const char *ifname);

#define _POSIX_C_SOURCE 200112L
#include <net/if.h>

unsigned int if_nametoindex(const char *ifname);

General description

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

Returned value

When successful, if_nametoindex() returns the interface index corresponding to the interface name ifname. Upon failure, if_nametoindex() returns zero and sets errno to one of the following:

Error Code

Description

EINVAL

Non-valid parameter was specified. The ifname parameter was NULL.

ENOMEM

Insufficient storage is available to obtain the information for the interface name.

ENXIO

The specified interface name provided in the ifname parameter does not exist.

Related information

• if_freenameindex() — Free the memory allocated by if_nameindex()
• if_indextoname() — Map a network interface index to its corresponding name
• if_nameindex() — Return all network interface names and indexes