ETHERS(3)                 OpenBSD Programmer's Manual                ETHERS(3)

NAME
     ether_aton, ether_ntoa, ether_addr, ether_ntohost, ether_hostton,
     ether_line - get ethers entry



SYNOPSIS
     #include <netinet/if_ether.h>

     char *
     ether_ntoa(struct ether_addr *e);

     struct ether_addr *
     ether_aton(char *s);

     int
     ether_ntohost(char *hostname, struct ether_addr *e);

     int
     ether_hostton(char *hostname, struct ether_addr *e);

     int
     ether_line(char *l, struct ether_addr *e, char *hostname);

DESCRIPTION
     Ethernet addresses are represented by the following structure:

           struct ether_addr {
                   u_int8_t  ether_addr_octet[6];
           };

     The ether_ntoa() function converts this structure into an ASCII string of
     the form ``xx:xx:xx:xx:xx:xx'', consisting of 6 hexadecimal numbers sepa-
     rated by colons.  It returns a pointer to a static buffer that is reused
     for each call.  The ether_aton() converts an ASCII string of the same
     form and to a structure containing the 6 octets of the address.  It re-
     turns a pointer to a static structure that is reused for each call.

     The ether_ntohost() and ether_hostton() functions interrogate the data
     base mapping host names to Ethernet addresses, /etc/ethers. The
     ether_ntohost() function looks up the given Ethernet address and writes
     the associated host name into the character buffer passed.  This buffer
     should be MAXHOSTNAMELEN characters in size.  The ether_hostton() func-
     tion looks up the given host name and writes the associated Ethernet ad-
     dress into the structure passed.  Both functions return zero if they find
     the requested host name or address, and -1 if not.

     Each call reads /etc/ethers from the beginning; if a `+' appears alone on
     a line in the file, then ether_hostton() will consult the ethers.byname
     YP map, and ether_ntohost() will consult the ethers.byaddr YP map.

     The ether_line() function parses a line from the /etc/ethers file and
     fills in the passed struct ether_addr and character buffer with the Eth-
     ernet address and host name on the line.  It returns zero if the line was
     successfully parsed and -1 if not.  The character buffer should be
     MAXHOSTNAMELEN characters in size.

FILES
     /etc/ethers

SEE ALSO
     ethers(5)

HISTORY
     The ether_ntoa(), ether_aton(), ether_ntohost(), ether_hostton(), and
     ether_line() functions were adopted from SunOS and appeared in NetBSD
     0.9b.

BUGS
     The data space used by these functions is static; if future use requires
     the data, it should be copied before any subsequent calls to these func-
     tions overwrite it.

OpenBSD 2.6                    December 16, 1993                             2