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.\" @(#)sliplogin.8 5.4 (Berkeley) 8/5/91
.Nd attach a serial line network interface
is used to turn the terminal line on standard input into
link to a remote host. To do this, the program
(which defaults to the current login name if omitted).
If a matching entry is found, the line is configured appropriately
for slip (8-bit transparent i/o) and converted to
discipline. Then a shell script is invoked to initialize the slip
interface with the appropriate local and remote
The usual initialization script is
but, if particular hosts need special initialization, the file
.Pa /etc/slip.login. Ns Ar loginname
will be executed instead if it exists.
The script is invoked with the parameters
The unit number of the slip interface assigned to this line. E.g.,
entry, in order starting with
Only the super-user may attach a network interface. The interface is
automatically detached when the other end hangs up or the
process dies. If the kernel slip
module has been configured for it, all routes through that interface will
also disappear at the same time. If there is other processing a site
would like done on hangup, the file
.Pa /etc/slip.logout. Ns Ar loginname
is executed if it exists. It is given the same arguments as the login script.
.Ss Format of /etc/slip.hosts
Comments (lines starting with a `#') and blank lines are ignored.
Other lines must start with a
but the remaining arguments can be whatever is appropriate for the
file that will be executed for that name.
Arguments are separated by white space and follow normal
quoting conventions (however,
Usually, lines have the form
.Bd -literal -offset indent
loginname local-address remote-address netmask opt-args
are the IP host names or addresses of the local and remote ends of the
is the appropriate IP netmask. These arguments are passed
are optional arguments used to configure the line.
entry for each legal, remote slip site with
as the shell for that entry. E.g.,
Sfoo:ikhuy6:2010:1:slip line to foo:/tmp:/etc/sliplogin
(Our convention is to name the account used by remote host
Then an entry is added to
.Bd -literal -offset indent -compact
Sfoo `hostname` foo netmask
to the local host name and
is the local host IP netmask.
must be setuid to root and, while not a security hole, moral defectives
can use it to place terminal lines in an unusable state and/or deny
access to legitimate users of a remote slip line. To prevent this,
a site can create a group, say
that only the slip login accounts are put in then make sure that
and mode 4550 (setuid root, only group
logs various information to the system log daemon,
The messages are listed here, grouped by severity level.
.Bl -tag -width Ds -compact
.It Sy ioctl (TCGETS): Em reason
to get the line parameters failed.
.It Sy ioctl (TCSETS): Em reason
to set the line parameters failed.
.It Sy /etc/slip.hosts: Em reason
file could not be opened.
.It Sy access denied for Em user
.Bl -tag -width Ds -compact
.It Sy "attaching slip unit" Em unit Sy for Ar loginname
was successfully attached.