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sliplogin ()
>> sliplogin (8) ( FreeBSD man: Команды системного администрирования )
sliplogin (8) ( Linux man: Команды системного администрирования )
BSD mandoc
NAME
sliplogin
- attach a serial line network interface
SYNOPSIS
[loginname [device
]
]
DESCRIPTION
The
utility is used to turn the terminal line on standard input (or
device
into a Serial 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 using the optional line discipline parameters.
The optional line discipline parameters consist of one or more of
the following;
`normal'
`compress'
`noicmp'
or
`autocomp'
which correspond respectively to
`use normal line discipline'
(no header compression),
`enable VJ header compression'
`throw away ICMP packets'
and
`auto enable VJ header compression'
(only if the remote end of the link also supports it).
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/sliphome/slip.login
but, if particular 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
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
/etc/sliphome/slip.logout
or
/etc/sliphome/slip.logout. loginname
is executed 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 (or started
with space) 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
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.
FreeBSD Additions
An additional SLIP configuration file (if present) is
/etc/sliphome/slip.slparms
If particular hosts need different configurations, the file
/etc/sliphome/slip.slparms. loginname
will be parsed instead if it exists.
Format of /etc/sliphome/slip.slparms*
Comments (lines starting with a `#') and blank lines (or started with
space) are ignored.
This file contains from one to three numeric parameters separated with spaces,
in order:
keepaliveoutfill
and
slunit
keepalive
Set SLIP "keep alive" timeout in seconds.
If FRAME_END is not received in
this amount of time,
closes the line and exits.
The default value is no timeout (zero).
outfill
Set SLIP "out fill" timeout in seconds.
It forces at least one FRAME_END
to be sent during this time period, which is necessary for the "keep alive"
timeout on the remote side.
The default value is no timeout (zero).
slunit
Set the SLIP unit number directly.
Use with caution, because no check is made
for two interfaces with same number.
By default sliplogin dynamically assigns the unit number.
If latter two parameters are omitted, they will not affect the
corresponding SLIP configuration.
If any of first two parameters is equal to zero, it will not affect
the corresponding SLIP configuration.
FILES
/etc/sliphome/slip.hosts
list of host login names and parameters.
/etc/sliphome/slip.login
script executed when a connection is made.
/etc/sliphome/slip.login. loginname
script executed when a connection is made by
loginname
/etc/sliphome/slip.logout
script executed when a connection is lost.
/etc/sliphome/slip.logout. loginname
script executed when a connection is lost by
loginname
/etc/sliphome/slip.slparms
extra parameters file.
/etc/sliphome/slip.slparms. loginname
extra parameters file for
loginname
/var/run/ ttyXn .if
contains the name of the network interface used by the sliplogin process on
ttyXn
/var/run/ slX .pid
contains the PID of the sliplogin process which is using interface
slX
EXAMPLES
The normal use of
is to create a
/etc/passwd
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:/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(1)
to the local host name and
netmask
is the local host IP netmask.
Note that
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,
is installed as user
root
group
network
and mode 4550 so that only members of group
network
may run
.
The system administrator should make sure that all legitimate users
are a member of the correct group.
DIAGNOSTICS
The
utility 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
