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man pages section 3: Basic Library Functions

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Updated: Thursday, June 13, 2019
 
 

ethers(3C)

Name

ethers, ether_ntoa, ether_aton, ether_ntohost, ether_hostton, ether_line - Ethernet address mapping operations

Synopsis

#include <sys/types.h>
#include <sys/ethernet.h>

char *ether_ntoa(const struct ether_addr *e);
struct ether_addr *ether_aton(const char *s);
int ether_ntohost(char *hostname, const struct ether_addr *e);
int ether_hostton(const char *hostname, struct ether_addr *e);
int ether_line(const char *l, struct ether_addr *e, char *hostname);

Description

These routines are useful for mapping 48 bit Ethernet numbers to their ASCII representations or their corresponding host names, and vice versa.

The function ether_ntoa() converts a 48 bit Ethernet number pointed to by e to its standard ASCII representation; it returns a pointer to the ASCII string. The representation is of the form x :  x : x :  x : x : x where x is a hexadecimal number between 0 and ff . The function ether_aton() converts an ASCII string in the standard representation back to a 48 bit Ethernet number; the function returns NULL if the string cannot be scanned successfully.

The function ether_ntohost() maps an Ethernet number (pointed to by e) to its associated hostname. The string pointed to by hostname must be long enough to hold the hostname and a NULL character. The function returns zero upon success and non-zero upon failure. Inversely, the function ether_hostton() maps a hostname string to its corresponding Ethernet number; the function modifies the Ethernet number pointed to by e. The function also returns zero upon success and non-zero upon failure. In order to do the mapping, both these functions may lookup one or more of the following sources: the ethers file, and the NIS maps ethers.byname and ethers.byaddr. The sources and their lookup order are specified in the /etc/nsswitch.conf file. See nsswitch.conf(5) for details.

The function ether_line() scans a line, pointed to by l, and sets the hostname and the Ethernet number, pointed to by e. The string pointed to by hostname must be long enough to hold the hostname and a NULL character. The function returns zero upon success and non-zero upon failure. The format of the scanned line is described by ethers(5).

Files

/etc/ethers

Ethernet address to hostname database or domain

/etc/nsswitch.conf

configuration file for the name service switch

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
MT-Level
MT-Safe

See Also

ethers(5), nsswitch.conf(5), attributes(7)