ethers.3n

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH ethers 3n
.SH Name
ethers, ether_ntoa, ether_aton, ether_ntohost, ether_hostton, ether_line \- Ethernet address mapping operations
.SH Syntax
.nf
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
.sp
char *
ether_ntoa(e)
	struct ether_addr *e;
.sp
struct ether_addr *
ether_aton(s)
	char *s;
.sp
ether_ntohost(hostname, e)
	char *hostname;
	struct ether_addr *e;
.sp
ether_hostton(hostname, e)
	char *hostname;
	struct ether_addr *e;
.sp
ether_line(l, e, hostname)
	char *l;
	struct ether_addr *e;
	char *hostname;
.fi
.SH Arguments
The 
.PN ether_addr
structure is defined as:
.EX
\f(CWstruct ether_addr {
        u_char  ether_addr_octet[6];
};
.EE
.SH Description
These routines are useful for mapping 48 bit Ethernet numbers to their
ASCII
representations or their corresponding host names, and vice versa.
.NXR "Ethernet address mapping operations"
The mapping is obtained from the
.PN /etc/ethers
database; see
.MS ethers 5 .
.PP
The function
.PN ether_ntoa(\|)
converts a 48 bit Ethernet number pointed to by
.I e
to its standard ACSII
representation; it returns a pointer to the ASCII
string.  The representation is of the form:
.IR x : x : x :\c
.IR x : x : x
where
.I x
is a hexadecimal number between 0 and ff.
The function
.PN 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.
.PP
The function
.PN ether_ntohost(\|)
maps an Ethernet number (pointed to by
.IR e )
to its associated hostname.  The string pointed to by
.PN 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
.PN ether_hostton(\|)
maps a hostname string to its corresponding Ethernet number;
the function modifies the Ethernet number pointed to by
.IR e .
The function also returns zero upon success and non-zero upon failure.
.PP
The function
.PN ether_line(\|)
scans a line (pointed to by
.IR l )
and sets the hostname and the Ethernet number (pointed to by
.IR e ).
The string pointed to by
.PN 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
.MS ethers 5 .
.SH Files
.TP 20
.PN /etc/ethers
.SH See Also
packetfilter(4), ethers(5), rarpd(8c)