if_nametoindex, if_indextoname - mappings between network interface names and indexes
#include <net/if.h>
unsigned int if_nametoindex(const char *ifname);
char *if_indextoname(unsigned int ifindex, char *ifname);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.
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.
if_nametoindex() may fail and set errno
if:
No interface found with given name.
if_indextoname() may fail and set errno
if:
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).
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| if_nametoindex(), if_indextoname() | Thread safety | MT-Safe |
POSIX.1-2001, POSIX.1-2008, RFC 3493.
This function first appeared in BSDi.
getifaddrs(3), if_nameindex(3), ifconfig(8)
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