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(),              │ Thread safety │ MT-Safe   │
       │ether_ntoa_r(), 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)