Copyright (c) 1990 The Regents of the University of California. All rights reserved. %sccs.include.redist.man% @(#)sliplogin.8 5.2 (Berkeley) 07/01/90 SLIPLOGIN 8 ""
NAME
sliplogin - attach a serial line network interface
SYNOPSIS
sliplogin [
loginname ]
DESCRIPTION
sliplogin is used to turn the terminal line on standard input into
a Serial Line IP (SLIP) link to a remote host. To do this, the program
searches the file
/etc/slip.hosts for an entry matching
loginname (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 SLIP line
discipline. Then a shell script is invoked to initialize the slip
interface with the appropriate local and remote IP address,
netmask, etc.
The usual initialization script is
/etc/slip.login but, if particular hosts need special initialization, the file
/etc/slip.login. loginname will be executed instead if it exists.
The script is invoked with the parameters
slipunit The unit number of the slip interface assigned to this line. E.g.,
0 for
sl0 .
speed The speed of the line.
args The arguments from the
/etc/slip.hosts entry, in order starting with
loginname .
Only the super-user may attach a network interface. The interface is
automatically detached when the other end hangs up or the
sliplogin 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
/etc/slip.logout or
/etc/slip.logout. loginname is executed if it exists. It is given the same arguments as the login script.
Comments (lines starting with a `#') and blank lines are ignored.
Other lines must start with a
loginname but the remaining arguments can be whatever is appropriate for the
slip.login file that will be executed for that name.
Arguments are separated by white space and follow normal
sh (1) quoting conventions (however,
loginname cannot be quoted).
Usually, lines have the form
loginname local-address remote-address netmask opt-args
where
local-address and
remote-address are the IP host names or addresses of the local and remote ends of the
slip line and
netmask is the appropriate IP netmask. These arguments are passed
directly to
ifconfig (8). Opt-args are optional arguments used to configure the line.
EXAMPLE
The normal use of
sliplogin is to create a
/etc/passwd entry for each legal, remote slip site with
sliplogin as the shell for that entry. E.g.,
(Our convention is to name the account used by remote host
hostname as
Shostname .) Then an entry is added to
slip.hosts that looks like:
Sfoo `hostname` foo netmask
where
`hostname` will be evaluated by
sh to the local host name and
netmask is the local host IP netmask.
Note that
sliplogin 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
slip , that only the slip login accounts are put in then make sure that
/etc/sliplogin is in group
slip and mode 4550 (setuid root, only group
slip can execute binary).
"DIAGNOSTICS"
sliplogin logs various information to the system log daemon,
syslogd (8), with a facility code of
daemon . The messages are listed here, grouped by severity level.
Err Severity
"ioctl (TCGETS): " reason A
TCGETS ioctl to get the line parameters failed.
"ioctl (TCSETS): " reason A
TCSETS ioctl to set the line parameters failed.
"/etc/slip.hosts: " reason The
/etc/slip.hosts file could not be opened.
"access denied for " user No entry for
user was found in
/etc/slip.hosts .
Notice Severity
"attaching slip unit " unit " for " loginname SLIP unit
unit was successfully attached.
"SEE ALSO"
slattach (8), syslogd (8)