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.
net/if.h — sockets local interfaces
header shall define the if_nameindex
structure, which shall include at least the following members:
unsigned if_index Numeric index of the interface.
char *if_name Null-terminated name of the interface.
header shall define the following symbolic constant
for the length of a buffer containing an interface name (including the
terminating NULL character):
- Interface name length.
The following shall be declared as functions and may also be defined as macros.
Function prototypes shall be provided.
The following sections are informative.
void if_freenameindex(struct if_nameindex *);
char *if_indextoname(unsigned, char *);
struct if_nameindex *if_nameindex(void);
unsigned if_nametoindex(const char *);
The System Interfaces volume of POSIX.1‐2008,
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
7, Copyright (C) 2013 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013
Technical Corrigendum 1 applied.) In the event of any discrepancy between this
version and the original IEEE and The Open Group Standard, the original IEEE
and The Open Group Standard is the referee document. The original Standard can
be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely
to have been introduced during the conversion of the source files to man page
format. To report such errors, see