.\"	$NetBSD: sl.4,v 1.1 1996/08/10 21:26:14 explorer Exp $
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.\"     From:	@(#)lo.4	8.1 (Berkeley) 6/5/93
.\" $FreeBSD: src/share/man/man4/sl.4,v 1.8.2.1 2000/12/08 14:59:08 ru Exp $
.\" $DragonFly: src/share/man/man4/sl.4,v 1.2 2003/06/17 04:36:59 dillon Exp $
.\"
.Dd August 10, 1996
.Dt SL 4
.Os
.Sh NAME
.Nm sl
.Nd slip network interface
.Sh SYNOPSIS
.Cd "pseudo-device sl" Op Ar count
.Sh DESCRIPTION
The
.Nm
interface allows serial lines to be used as network interfaces using the
.Em slip
protocol.  The
.Nm
interface can use Van Jacobson TCP header compression and ICMP filtering.
This is arranged by using the various link-level flags to the
.Xr ifconfig 8
command:
.Pp
.Bl -tag -width LINK0X -compact
.It Em link0
Enable VJ header compression.
.It Em link1
Suppress ICMP traffic.
.It Em link2
Enable VJ header compression autodetection.  This will turn on the
.Em link0
flag as soon as the first VJ-compressed packet has been seen by
the driver.
.El
.Sh DIAGNOSTICS
.Bl -diag
.It sl%d: af%d not supported.
The interface was handed
a message with addresses formatted in an unsuitable address
family; the packet was dropped.
.El
.Sh SEE ALSO
.Xr inet 4 ,
.Xr intro 4 ,
.Xr slattach 8 ,
.Xr sliplogin 8 ,
.Xr slstat 8