193 lines
5.1 KiB
Groff
193 lines
5.1 KiB
Groff
.\" Copyright (c) 1995
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.\" Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Bill Paul.
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.\" 4. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 12, 1995
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.Dt ETHERS 3
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.Os FreeBSD 2.1
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.Sh NAME
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.Nm ethers ,
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.Nm ether_line ,
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.Nm ether_aton ,
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.Nm ether_ntoa ,
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.Nm ether_ntohost ,
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.Nm ether_hostton
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.Nd Ethernet address conversion and lookup routines
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/socket.h>
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.Fd #include <net/ethernet.h>
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.Ft int
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.Fn ether_line "char *l" "struct ether_addr *e" "char *hostname"
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.Ft struct ether_addr *
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.Fn ether_aton "char *a"
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.Ft char *
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.Fn ether_ntoa "struct ether_addr *n"
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.Ft int
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.Fn ether_ntohost "char *hostname" "struct ether_addr *e"
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.Ft int
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.Fn ether_hostton "char *hostname" "struct ether_addr *e"
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.Sh DESCRIPTION
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These functions operate on ethernet addresses using an
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.Ar ether_addr
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structure, which is defined in the header file
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.Aq Pa netinet/if_ether.h :
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.Bd -literal -offset indent
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/*
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* The number of bytes in an ethernet (MAC) address.
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*/
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#define ETHER_ADDR_LEN 6
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/*
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* Structure of a 48-bit Ethernet address.
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*/
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struct ether_addr {
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u_char octet[ETHER_ADDR_LEN];
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};
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.Ed
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.Pp
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The function
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.Fn ether_line
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scans
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.Ar l ,
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an
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.Tn ASCII
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string in
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.Xr ethers 5
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format and sets
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.Ar e
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to the ethernet address specified in the string and
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.Ar h
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to the hostname. This function is used to parse lines from
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.Pa /etc/ethers
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into their component parts.
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.Pp
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The
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.Fn ether_aton
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function converts an
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.Tn ASCII
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representation of an ethernet address into an
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.Ar ether_addr
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structure. Likewise,
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.Fn ether_ntoa
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converts an ethernet address specified as an
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.Ar ether_addr
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structure into an
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.Tn ASCII
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string.
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.Pp
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The
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.Fn ether_ntohost
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and
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.Fn ether_hostton
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functions map ethernet addresses to their corresponding hostnames
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as specified in the
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.Pa /etc/ethers
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database.
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.Fn ether_ntohost
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converts from ethernet address to hostname, and
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.Fn ether_hostton
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converts from hostname to ethernet address.
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.Sh RETURN VALUES
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.Fn ether_line
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returns zero on success and non-zero if it was unable to parse
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any part of the supplied line
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.Ar l .
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It returns the extracted ethernet address in the supplied
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.Ar ether_addr
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structure
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.Ar e
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and the hostname in the supplied string
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.Ar h .
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.Pp
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On success,
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.Fn ether_ntoa
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returns a pointer to a string containing an
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.Tn ASCII
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representation of an ethernet address. If it is unable to convert
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the supplied
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.Ar ether_addr
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structure, it returns a
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.Dv NULL
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pointer. Likewise,
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.Fn ether_aton
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returns a pointer to an
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.Ar ether_addr
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structure on success and a
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.Dv NULL
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pointer on failure.
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.Pp
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The
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.Fn ether_ntohost
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and
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.Fn ether_hostton
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functions both return zero on success or non-zero if they were
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unable to find a match in the
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.Pa /etc/ethers
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database.
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.Sh NOTES
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The user must insure that the hostname strings passed to the
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.Fn ether_line ,
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.Fn ether_ntohost
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and
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.Fn ether_hostton
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functions are large enough to contain the returned hostnames.
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.Sh NIS INTERACTION
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If the
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.Pa /etc/ethers
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contains a line with a single + in it, the
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.Fn ether_ntohost
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and
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.Fn ether_hostton
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functions will attempt to consult the NIS
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.Pa ethers.byname
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and
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.Pa ethers.byaddr
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maps in addition to the data in the
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.Pa /etc/ethers
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file.
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.Sh SEE ALSO
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.Xr yp 4 ,
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.Xr ethers 5
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.Sh BUGS
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.Pp
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The
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.Fn ether_aton
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and
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.Fn ether_ntoa
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functions returns values that are stored in static memory areas
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which may be overwritten the next time they are called.
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.Sh HISTORY
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This particular implementation of the
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.Nm ethers
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library functions were written for and first appeared in
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.Fx 2.1 .
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