SLIPLOGIN(8) MachTen System Manager’s Manual 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 Se-
rial Line IP (SLIP) link to a remote host. To do this, the
program
searches the file /etc/sliphome/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 appro-
priate local and remote IP address, netmask, etc.
The usual initialization script
is /etc/sliphome/slip.login but, if par-
ticular hosts need special initialization, the file
/etc/sliphome/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/sliphome/slip.hosts entry, in order
starting with loginname.
Only the super-user may attach a
network interface. The interface is au-
tomatically 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/sliphome/slip.logout or
/etc/sliphome/slip.logout.loginname is exe-
cuted if it exists. It is given the same arguments as the
login script.
Format of
/etc/sliphome/slip.hosts
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). Usual-
ly, 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 appro-
priate 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 le-
gal, remote slip site with sliplogin as the shell for that
entry. E.g.,
Sfoo:ikhuy6:2010:1:slip line to foo:/tmp:/usr/sbin/sliplogin
(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 lo-
gin accounts are put in then make sure that
/usr/sbin/sliplogin is in
group slip and mode 4550 (setuid root, only group slip can
execute bina-
ry).
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.
Error 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/sliphome/slip.hosts: reason
The /etc/sliphome/slip.hosts file could not be opened.
access denied for user
No entry for user was found in /etc/sliphome/slip.hosts.
Notice Severity
attaching slip unit unit for loginname
SLIP unit unit was successfully attached.
SEE ALSO
slattach(8), syslogd(8)
HISTORY
The sliplogin command is currently in beta test.
4.4BSD January 5, 1994 2