ETHER_ATON(3)

NAME
ether_aton, ether_ntoa, ether_ntohost, ether_hostton, ether_line, ether_ntoa_r, ether_aton_r - Ethernet address manipulation routines

SYNOPSIS
#include <netinet/ether.h>

char *ether_ntoa(const struct ether_addr *addr);

struct ether_addr *ether_aton(const char *asc);

int ether_ntohost(char *hostname, const struct ether_addr *addr);

int ether_hostton(const char *hostname, struct ether_addr *addr);

int ether_line(const char *line, struct ether_addr *addr,
               char *hostname);

/* GNU extensions */
char *ether_ntoa_r(const struct ether_addr *addr, char *buf);

struct ether_addr *ether_aton_r(const char *asc,
                                struct ether_addr *addr);

DESCRIPTION
ether_aton() converts the 48-bit Ethernet host address asc from the standard hex-digits-and-colons notation into binary data in network byte order and returns a pointer to it in a statically allocated buffer, which subsequent calls will overwrite. ether_aton() returns NULL if the address is invalid.

The ether_ntoa() function converts the Ethernet host address addr given in network byte order to a string in standard hex-digits-and-colons notation, omitting leading zeroes. The string is returned in a statically allocated buffer, which subsequent calls will overwrite.

The ether_ntohost() function maps an Ethernet address to the corresponding hostname in /etc/ethers and returns non-zero if it cannot be found.

The ether_hostton() function maps a hostname to the corresponding Ethernet address in /etc/ethers and returns non-zero if it cannot be found.

The ether_line() function parses a line in /etc/ethers format (ethernet address followed by whitespace followed by hostname; '#' introduces a comment) and returns an address and hostname pair, or non-zero if it cannot be parsed. The buffer pointed to by hostname must be sufficiently long, for example, have the same length as line.

The functions ether_ntoa_r() and ether_aton_r() are re-entrant threadsafe versions of ether_ntoa() and ether_aton() respectively, and do not use static buffers.

The structure ether_addr is defined in net/ethernet.h as:

struct ether_addr {
    u_int8_t ether_addr_octet[6];
}

CONFORMING TO
4.3BSD, SunOS

BUGS
The glibc 2.2.5 implementation of ether_line() is broken.

SEE ALSO
ethers(5)