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8 .TH ETHERS 3SOCKET "Aug 9, 2014"
10 ethers, ether_ntoa, ether_ntoa_r, ether_aton, ether_aton_r, ether_ntohost, ether_hostton, ether_line \-
11 Ethernet address mapping operations
15 \fBcc\fR [ \fIflag\fR ... ] \fIfile\fR ... \fB-lsocket\fR \fB -lnsl \fR [ \fIlibrary\fR ... ]
16 #include <sys/types.h>
17 #include <sys/ethernet.h>
19 \fBchar *\fR\fBether_ntoa\fR(\fBconst struct ether_addr *\fR\fIe\fR);
24 \fBchar *\fR\fBether_ntoa_r\fR(\fBconst struct ether_addr *\fR\fIe\fR, \fBchar *\fR\fIs\fR);
29 \fBstruct ether_addr *\fR\fBether_aton\fR(\fBconst char *\fR\fIs\fR);
34 \fBstruct ether_addr *\fR\fBether_aton_r\fR(\fBconst char *\fR\fIs\fR, \fBstruct ether_addr *\fR\fIe\fR);
39 \fBint\fR \fBether_ntohost\fR(\fBchar *\fR\fIhostname\fR, \fBconst struct ether_addr *\fR\fIe\fR);
44 \fBint\fR \fBether_hostton\fR(\fBconst char *\fR\fIhostname\fR, \fBstruct ether_addr *\fR\fIe\fR);
49 \fBint\fR \fBether_line\fR(\fBconst char *\fR\fIl\fR, \fBstruct ether_addr *\fR\fIe\fR, \fBchar *\fR\fIhostname\fR);
54 These routines are useful for mapping 48 bit Ethernet numbers to their ASCII
55 representations or their corresponding host names, and vice versa.
58 The function \fBether_ntoa()\fR converts a 48 bit Ethernet number pointed to by
59 \fIe\fR to its standard \fBASCII\fR representation; it returns a pointer to
60 the \fBASCII\fR string. The representation is of the form
61 \fIx\fR\|:\|\fIx\fR\|:\|\fIx\fR\|:\| \fIx\fR\|:\|\fIx\fR\|:\|\fIx\fR where
62 \fIx\fR is a hexadecimal number between \fB0\fR and \fBff\fR. The function
63 \fBether_aton()\fR converts an \fBASCII\fR string in the standard
64 representation back to a 48 bit Ethernet number; the function returns
65 \fINULL\fR if the string cannot be scanned successfully.
68 The functions \fBether_ntoa()\fR and \fBether_aton()\fR return values in
69 per-thread buffers, one for each function. A second call to one of these
70 functions will overwrite the previous value. The functions
71 \fBether_ntoa_r()\fR and \fBether_aton_r()\fR behave identically to
72 their non-reentrant versions; however, instead of using a per-thread
73 buffer, they use caller supplied buffers. It is the callers
74 responsibility to ensure that the character buffer passed to
75 \fBether_ntoa_r()\fR is at least \fBETHERADDRSTRL\fR bytes large -- the
76 minimum size to hold the ASCII representation of a 48 bit Ethernet
77 number and a null terminator.
80 The function \fBether_ntohost()\fR maps an Ethernet number (pointed to by
81 \fIe\fR) to its associated hostname. The string pointed to by hostname must be
82 long enough to hold the hostname and a \fINULL\fR character. The function
83 returns zero upon success and non-zero upon failure. Inversely, the function
84 \fBether_hostton()\fR maps a hostname string to its corresponding Ethernet
85 number; the function modifies the Ethernet number pointed to by \fIe\fR. The
86 function also returns zero upon success and non-zero upon failure. In order to
87 do the mapping, both these functions may lookup one or more of the following
88 sources: the ethers file, the \fBNIS\fR maps \fBethers.byname\fR and
89 \fBethers.byaddr\fR and the \fBNIS+\fR table \fBethers\fR. The sources and
90 their lookup order are specified in the \fB/etc/nsswitch.conf\fR file. See
91 \fBnsswitch.conf\fR(4) for details.
94 The function \fBether_line()\fR scans a line, pointed to by \fIl\fR, and sets
95 the hostname and the Ethernet number, pointed to by \fIe\fR. The string pointed
96 to by hostname must be long enough to hold the hostname and a \fINULL\fR
97 character. The function returns zero upon success and non-zero upon failure.
98 The format of the scanned line is described by \fBethers\fR(4).
102 \fB\fB/etc/ethers\fR\fR
105 Ethernet address to hostname database or domain
111 \fB\fB/etc/nsswitch.conf\fR\fR
114 configuration file for the name service switch
119 See \fBattributes\fR(5) for descriptions of the following attributes:
127 ATTRIBUTE TYPE ATTRIBUTE VALUE
134 \fBethers\fR(4), \fBnsswitch.conf\fR(4), \fBattributes\fR(5)