if_nametoindex(3) — Linux manual page

if_nametoindex(3)       Library Functions Manual       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   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ if_nametoindex(), if_indextoname()  │ Thread safety │ MT-Safe │
       └─────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       POSIX.1-2008, RFC 3493.

HISTORY

       POSIX.1-2001.  BSDi.

SEE ALSO

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

COLOPHON

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Linux man-pages 6.9.1          2024-05-02              if_nametoindex(3)

Pages that refer to this page: if_nameindex(3)

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