if_nametoindex

IF_NAMETOINDEX(3)          Linux Programmer's Manual         IF_NAMETOINDEX(3)

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

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  inter-
       face 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 appropriately.

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

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  er-
       rors specified for socket(2) or ioctl(2).

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +-----------------------------------+---------------+---------+
       |Interface                          | Attribute     | Value   |
       +-----------------------------------+---------------+---------+
       |if_nametoindex(), if_indextoname() | Thread safety | MT-Safe |
       +-----------------------------------+---------------+---------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, RFC 3493.

       This function first appeared in BSDi.

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

COLOPHON
       This page is part of release 5.05 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

GNU                               2017-09-15                 IF_NAMETOINDEX(3)