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.\"     @(#)slattach.8	8.2 (Berkeley) 4/1/94
.\"
.Dd January 18, 2020
.Dt SLATTACH 8
.Os
.Sh NAME
.Nm slattach
.Nd attach serial lines as network interfaces
.Sh SYNOPSIS
.Nm
.Op Fl Hhlmn
.Op Fl s Ar baudrate
.Op Fl t Ar ldisc
.Ar ttyname
.Sh DESCRIPTION
.Nm
is used to assign a tty line to a network interface which uses asynchronous
serial lines.
.Pp
Currently the
.Nm
command is used to attach
.Xr sl 4
interfaces.
These interfaces have to be created using the
.Xr ifconfig 8 .
The resulting point-to-point link is not a broadcast interface
and normally has a netmask of 255.255.255.255.
.Cm create
subcommand before the
.Nm
command.
The network source and destination addresses and other interface parameters
are configured via
.Xr ifconfig 8 .
.Pp
The following operands are supported by
.Nm :
.Bl -tag -width Ar
.It Fl H
Turn on DTR/CTS flow control.
By default, no flow control is done.
.It Fl h
Turn on RTS/CTS flow control.
By default, no flow control is done.
.It Fl l
Turn on the CLOCAL flag, making it possible to run SLIP on a cable
without modem control signals (e.g. DTR, DSR, DCD).
.It Fl m
Maintain modem control signals after closing the line.
Specifically, this disables HUPCL.
.It Fl n
Don't detach from invoking tty.
.It Fl s Ar baudrate
Specifies the speed of the connection.
If not specified, the default of 9600 is used.
.It Fl t Ar ldisc
Specifies the line discipline to use for the tty.
Supported line disciplines are
.Dq slip
(creates a
.Xr sl 4
instance).
If this option is not specified, the default is
.Dq slip .
This option is retained for backwards compatibility with existing
scripts.
.It Ar ttyname
Specifies the name of the tty device.
.Ar ttyname
should be a string of the form
.Ql ttyXX ,
or
.Ql /dev/ttyXX .
.El
.Pp
Only the super-user may attach a network interface.
.Pp
To detach the interface, use
.Dq Li ifconfig interface-name down
after killing off the
.Nm
process.
.Ar Interface-name
is the name that is shown by
.Xr netstat 1 .
.Sh EXAMPLES
Lock, initialize, and attach a line (on both sides):
.Bd -literal -offset indent -compact
cu -t -F [hard|soft] -l /dev/dty00
ifconfig sl0 create
slattach -l -t slip /dev/dty00
.Ed
On the local side:
.Bd -literal -offset indent -compact
ifconfig sl0 inet 10.0.0.2 10.0.0.1 netmask 255.255.255.255
.Ed
On the remote side:
.Bd -literal -offset indent -compact
ifconfig sl0 inet 10.0.0.1 10.0.0.2 netmask 255.255.255.255
.Ed
.Sh DIAGNOSTICS
Messages indicating that the specified interface is not configured or created,
the requested address is unknown, or that the user is not privileged
but tried to alter an interface's configuration.
.Sh SEE ALSO
.Xr netstat 1 ,
.Xr daemon 3 ,
.Xr netintro 4 ,
.Xr sl 4 ,
.Xr ifconfig 8 ,
.Xr rc 8 ,
.Xr sliplogin 8 ,
.Xr slstats 8
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
.Sh BUGS
There is no way to specify the interface name (sl%d etc.) to be attached by the
.Nm
command.
There is no way to see which interface is assigned to the specified tty by the
.Nm
command, either.
.Pp
It would be better if the network interfaces were created by the
.Nm
command rather than by using the
.Xr ifconfig 8
.Cm create
subcommand before the
.Nm
command.