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ETHERS (3) | C library functions | Unix Manual Pages | :man

NAME

ethers, ether_line, ether_aton, ether_ntoa, ether_ntohost, ether_hostton - Ethernet address conversion and lookup routines

CONTENTS

Library
Synopsis
Description
Return Values
Notes
Nis Interaction
See Also
History
Bugs

LIBRARY


.Lb libc

SYNOPSIS


.In sys/types.h
.In sys/socket.h
.In net/ethernet.h int ether_line "const char *l" "struct ether_addr *e" "char *hostname" struct ether_addr * ether_aton "const char *a" char * ether_ntoa "const struct ether_addr *n" int ether_ntohost "char *hostname" "const struct ether_addr *e" int ether_hostton "const char *hostname" "struct ether_addr *e"

DESCRIPTION

These functions operate on ethernet addresses using an
.Vt ether_addr structure, which is defined in the header file
.In netinet/if_ether.h :
/*
* The number of bytes in an ethernet (MAC) address.
*/
#define ETHER_ADDR_LEN6


/*
* Structure of a 48-bit Ethernet address.
*/
struct ether_addr {
u_char octet[ETHER_ADDR_LEN];
};

The function ether_line scans l, an ASCII 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 ether_aton function converts an ASCII representation of an ethernet address into an
.Vt ether_addr structure. Likewise, ether_ntoa converts an ethernet address specified as an
.Vt ether_addr structure into an ASCII string.

The ether_ntohost and ether_hostton functions map ethernet addresses to their corresponding hostnames as specified in the /etc/ethers database. The ether_ntohost function converts from ethernet address to hostname, and ether_hostton converts from hostname to ethernet address.

RETURN VALUES

The ether_line function 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
.Vt ether_addr structure e and the hostname in the supplied string h.

On success, ether_ntoa returns a pointer to a string containing an ASCII representation of an ethernet address. If it is unable to convert the supplied
.Vt ether_addr structure, it returns a NULL pointer. Likewise, ether_aton returns a pointer to an
.Vt ether_addr structure on success and a NULL pointer on failure.

The ether_ntohost and ether_hostton 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 ether_line, ether_ntohost and ether_hostton functions are large enough to contain the returned hostnames.

NIS INTERACTION

If the /etc/ethers contains a line with a single + in it, the ether_ntohost and ether_hostton 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

ethers(5), yp(8)

HISTORY

BUGS


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