ETHERS(3)                BSD Library Functions Manual                ETHERS(3)

NAME
     ethers, etherline, etheraton, etherntoa, etherntohost, etherhostton
     -- Ethernet address conversion and lookup routines

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##include <>
     ##include <>
     ##include <>

     int
     etherline(const char *l, struct etheraddr *e, char *hostname);

     struct etheraddr *
     etheraton(const char *a);

     char *
     etherntoa(const struct etheraddr *n);

     int
     etherntohost(char *hostname, const struct etheraddr *e);

     int
     etherhostton(const char *hostname, struct etheraddr *e);

DESCRIPTION
     These functions operate on ethernet addresses using an etheraddr struc-
     ture, which is defined in the header file :

           /*
            * The number of bytes in an ethernet (MAC) address.
            */
           #define ETHERADRLEN          6

           /*
            * Structure of a 48-bit Ethernet address.
            */
           struct  etheraddr {
                   uchar octet[ETHERADRLEN];
           };

     The function etherline() scans l, an ASCI string in ethers(5) format
     and sets e to the ethernet address specified in the string and h to the
     hostname.  This function is used to parse lines from /etc/ethers into
     their component parts.

     The etheraton() function converts an ASCI representation of an ethernet
     address into an etheraddr structure.  Likewise, etherntoa() converts an
     ethernet address specified as an etheraddr structure into an ASCI
     string.

     The etherntohost() and etherhostton() functions map ethernet addresses
     to their corresponding hostnames as specified in the /etc/ethers data-
     base.  etherntohost() converts from ethernet address to hostname, and
     etherhostton() converts from hostname to ethernet address.

RETURN VALUES
     etherline() returns zero on success and non-zero if it was unable to
     parse any part of the supplied line l.  It returns the extracted ethernet
     address in the supplied etheraddr structure e and the hostname in the
     supplied string h.

     On success, etherntoa() returns a pointer to a string containing an
     ASCI representation of an ethernet address.  If it is unable to convert
     the supplied etheraddr structure, it returns a NUL pointer.  Likewise,
     etheraton() returns a pointer to an etheraddr structure on success and
     a NUL pointer on failure.

     The etherntohost() and etherhostton() functions both return zero on
     success or non-zero if they were unable to find a match in the
     /etc/ethers database.

NOTES
     The user must insure that the hostname strings passed to the
     etherline(), etherntohost() and etherhostton() functions are large
     enough to contain the returned hostnames.

NIS INTERACTION
     If the /etc/ethers contains a line with a single ] in it, the
     etherntohost() and etherhostton() functions will attempt to consult the
     NIS ethers.byname and ethers.byaddr maps in addition to the data in the
     /etc/ethers file.

SEE ALSO
     yp(4), ethers(5)

BUGS
     The etheraton() and etherntoa() functions returns values that are
     stored in static memory areas which may be overwritten the next time they
     are called.

HISTORY
     This particular implementation of the ethers library functions were writ-
     ten for and first appeared in FreeBSD 2.1.

BSD                             April 12, 1995                             BSD