Sliplogin
is used to turn the terminal line on standard input into
a Serial Line IP
Tn SLIP
link to a remote host. To do this, the program
searches the file
/etc/slip/slip.hosts
for an entry matching
loginname
(which defaults to the current login name if omitted).
The loginname '*' in slip.hosts matches every user so everyone
who can execute sliplogin and is not listed in slip.hosts will use
this default entry. If you really need a default user, please put this
entry at the last line in slip.hosts, so it will be used if the sliplogin
user is not listed in slip.hosts. If you put the default user as
first entry in slip.hosts all other entries will be ignored.
Another symbolic loginname is '+'. If a loginname starts with '+'
sliplogin will try to read the NIS map slip.hosts instead of slip.hosts.
You can override the local IP found in the NIS map by entering it after
the '+' sign.
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 (slip.login) is invoked to initialize
the slip interface with the appropriate local and remote
IP
address,
netmask, etc. (
Warning: the number of arguments changed with version 2.1.0
)
A line in slip.hosts usually consists of the fields loginname, local address,
remote address, netmask, slipmode, timeout and perhaps up to 3 more
options which will be passed to slip.login.
The usual initialization script is
/etc/slip/slip.login
but, if particular hosts need special initialization, the file
/etc/slip/slip.login. Ns Ar loginname
will be executed instead if it exists.
If you use the default user '*' sliplogin looks for slip.login.*,
but '*' is not used as a wildcard. If no slip.login.* exists,
the usual slip.login will be used.
The script is invoked with the parameters
-tag -width slipunit
Em slipunit
The unit identifier of the slip interface assigned to this line. E.g.,
sl0 .
Em speed
The speed of the line.
Em pid
The process id of sliplogin.
Em args
The arguments from the
/etc/slip/slip.hosts
entry:
loginname, local address, remote address, netmask, slip-mode
and the options.
(slip-mode has been added with version 2.1.0 of sliplogin.)
Only the super-user may attach a network interface. The interface is
automatically detached when the other end hangs up, the
sliplogin
process dies or the client didn't send a packet while the specified
timeout in /etc/slip/slip.hosts. 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/slip.logout
or
/etc/slip/slip.logout. Ns Ar loginname
is executed if it exists. It is given the same arguments as the login script.
For default user '*' sliplogin looks for slip.logout.* and if it doesn't
exist, it uses slip.logout.
Comments (lines starting with a `#') and blank lines are ignored.
Other lines must start with a
loginname
Arguments are separated by white space and follow normal
sh 1
quoting conventions (however,
loginname
cannot be quoted).
Usually, lines have the form
-literal -offset indent
loginname local-address remote-address netmask slipmode timeout opt-args
where
local-address
is the IP host name or address of the local end of the slip line or
DYNAMIC for the address of the local host.
remote-address
is the IP host name or address of the remote end of the slip line or
the DYNAMIC keyword which will be translated into an address from the
slip.tty file. You may also use an asterisk '*' instead of DYNAMIC.
netmask
is the appropriate IP netmask.
These arguments are passed
directly to
ifconfig 8 .
slipmode
is either normal, compressed, ax25, 6bit or auto where auto uses the
kernel auto detection to find out if the client uses normal or
compressed (Van Jacobson) slip.
timeout
is ignored if negative or else used as value in seconds to wait for
packets to be sent from the client before
sliplogin
terminates.
Opt-args
are optional arguments used to configure the line.
To perform an easy way to route additional hosts and networks you may
create a file
/etc/slip/slip.route
which contents are evaluated by
/etc/slip/slip.log{in|out}
to add or remove the given routes. The format is as follows
-literal -offset indent
gateway network [netmask]
Netmask defaults to
0xffffffff
if not given.
is simple. A line that starts with '#' is treated as a comment otherwise
sliplogin
expects in column 1 the name of the slipdevice and in column 2 the
IP host name or adress that you wish to assign to this device.
Since version 2.1.0 a new (more anonymous) login procedure is provided with
sliplogin as a compile time option. If the loginname matches the string
slip ,
sliplogin will ask for the user and an additional password.
If the given user and password matches an entry in
/etc/slip/slip.passwd
the line is configured for that user. If a user-name starts with
'+' in /etc/slip/slip.passwd sliplogin will try to read NIS-map
slip.passwd instead of slip.passwd.
One advantage of this method is, that you don't need a /etc/passwd
entry for each user login. On the other hand, the user himself may
choose the line discipline himself with the real login name. sliplogin
will distinguish between the following:
-tag -width ?slip-
Em slip
normal slip mode. With a compile-time option (-DESLIP_AUTO) this will
auto enable VJ header compression.
Em nslip
disable VJ header compression. (For those remote users who don't have
support for CSLIP mode and where auto enable fails.
Linux 1.2.x & HP-UX 9.x for example.)
Em cslip
enable VJ header compression.
Em aslip
auto enable VJ header compression, only tested if compiled without
general auto enabling (-DESLIP_AUTO) option.
With an additional '-' suffix sliplogin will suppress configure
messages like the using of the compression method and the assigning
of IP-adresses. An additional '+' will turn the messages on if not
compiled in by default.
You may also precede the login with an
additional letter to have a test mode with different binaries and
configuration options.