140 lines
3.9 KiB
Groff
140 lines
3.9 KiB
Groff
.\" $NetBSD: sl.4,v 1.17 2020/01/19 01:25:03 thorpej Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. 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. Neither the name of the University nor the names of its 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 THE REGENTS 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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.\" From: @(#)lo.4 8.1 (Berkeley) 6/5/93
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.\"
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.Dd January 18, 2020
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.Dt SL 4
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.Os
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.Sh NAME
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.Nm sl
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.Nd Serial Line IP (SLIP) network interface
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.Sh SYNOPSIS
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.Cd pseudo-device sl
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.Sh DESCRIPTION
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The
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.Nm
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interface allows asynchronous serial lines to be used as
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.Tn IPv4
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network interfaces using the
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.Tn SLIP
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protocol.
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.Pp
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To use the
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.Nm
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interface, the administrator must first create the interface and assign
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a tty line to it.
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The
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.Nm
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interface is created using the
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.Xr ifconfig 8
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.Cm create
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subcommand, and
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.Xr slattach 8
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is used to assign a tty line to the interface.
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Once the interface is attached, network source and destination addresses and
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other parameters are configured via
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.Xr ifconfig 8 .
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.Pp
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The
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.Nm
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interface can use Van Jacobson
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.Tn TCP
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header compression and
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.Tn ICMP
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filtering.
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The following flags to
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.Xr ifconfig 8
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control these properties of a SLIP link:
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.Bl -tag -width Ar
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.It Ar link0
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Turn on Van Jacobson header compression.
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.It Ar -link0
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Turn off header compression. (default)
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.It Ar link1
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Don't pass through ICMP packets.
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.It Ar -link1
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Do pass through ICMP packets. (default)
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.It Ar link2
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If a packet with a compressed header is received, automatically enable
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compression of outgoing packets. (default)
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.It Ar -link2
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Don't auto-enable compression.
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.El
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.Sh DIAGNOSTICS
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.Bl -diag
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.It sl%d: af%d not supported .
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The interface was handed
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a message with addresses formatted in an unsuitable address
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family; the packet was dropped.
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.El
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.Sh SEE ALSO
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.Xr inet 4 ,
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.Xr intro 4 ,
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.Xr ppp 4 ,
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.Xr ifconfig 8 ,
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.Xr slattach 8 ,
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.Xr sliplogin 8 ,
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.Xr slstats 8
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.Rs
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.%A J. Romkey
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.%R RFC
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.%N 1055
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.%D June 1988
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.%T "A Nonstandard for Transmission of IP Datagrams over Serial Lines: SLIP"
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.Re
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.Rs
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.%A Van Jacobson
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.%R RFC
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.%N 1144
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.%D February 1990
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.%T "Compressing TCP/IP Headers for Low-Speed Serial Links"
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.Re
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.Sh HISTORY
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The
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.Nm
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device appeared in
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.Nx 1.0 .
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.Sh BUGS
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.Tn SLIP
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can only transmit
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.Tn IPv4
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packets between preconfigured hosts on an asynchronous serial link.
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It has no provision for address negotiation,
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carriage of additional protocols (e.g.
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.Tn XNS ,
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.Tn AppleTalk ,
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.Tn DECNET ) ,
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and is not designed for synchronous serial links.
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This is why
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.Tn SLIP
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has been superseded by the Point-to-Point Protocol
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.Pq Tn PPP ,
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which does all of those things, and much more.
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