NAME

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

LIBRARY

       Standard C library (libc, -lc)

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  zeros.   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 nonzero if it cannot be found.

       The ether_hostton() function maps a hostname to the corresponding Ethernet  address  in  /etc/ethers  and
       returns nonzero 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  nonzero  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 reentrant thread-safe 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 {
               uint8_t ether_addr_octet[6];
           }

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌───────────────────────────────────────────────────────────────────────────┬───────────────┬───────────┐
       │ Interface                                                                 │ Attribute     │ Value     │
       ├───────────────────────────────────────────────────────────────────────────┼───────────────┼───────────┤
       │ ether_aton(), ether_ntoa()                                                │ Thread safety │ MT-Unsafe │
       ├───────────────────────────────────────────────────────────────────────────┼───────────────┼───────────┤
       │ ether_ntohost(), ether_hostton(), ether_line(), ether_ntoa_r(),           │ Thread safety │ MT-Safe   │
       │ ether_aton_r()                                                            │               │           │
       └───────────────────────────────────────────────────────────────────────────┴───────────────┴───────────┘

STANDARDS

       None.

HISTORY

       4.3BSD, SunOS.

BUGS

       In glibc 2.2.5 and earlier, the implementation of ether_line() is broken.

SEE ALSO

       ethers(5)

Linux man-pages 6.7                                2023-10-31                                      ether_aton(3)