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This is a small X based program that allows for easy activation and
deactivation of the demand-dialing feature of the Linux-ISDN
subsystem. It can also be used to initiate connections without using the demand-dialing feature.
It displays a symbolized traffic light. When the light is red, no
demand-dialing is possible; when it is yellow, demand-dialing has been
enabled but there is currently no connection using any of the ISDN
network devices; when it is green, there is at least one active
connection using an ISDN network device. You can interactively switch
between red and yellow/green by clicking with the left mouse button
into the window; the right mouse button pops up a menu to select
between different actions --- this can be used if you want to connect
to different providers.
ISDN-button is intended to be run inside of the FVWM button bar, but
you can also run it stand-alone. It has to be installed setuid-root in
order to access the ISDN and network devices! I tried to close the
most obvious security holes, but I cannot guarantee that this program
is secure; if you are paranoid or do not trust your users, you should
refrain from using ISDN-button (or submit a patch, that closes
possible security holes).
If you want to limit outdialing permissions to a selected group of
users, then you should add them to a new group. Make ISDN-button
executable by this group only.
At the very least, you will have to provide two shell scripts in
"/usr/sbin/isdn" or "/usr/local/sbin/isdn" (the exact location can be
changed in the source file); "connect" will be called when
demand-dialing is to be enabled (i.e. when the traffic light is red)
and "disconnect" will be called when it is to be disabled (i.e. when
the traffic light is yellow or green). This can be done either by
pressing the left mouse button or by selecting the shell script from
the menu that pops up when you press the right mouse button.
Typically, "connect" will have instructions for adding an outgoing
telephone number (e.g. "/sbin/isdnctrl addnum isdn0 out 555-1234"),
and setting up a default route (e.g. "/sbin/route add default gw
192.168.0.1 metric 1"); "disconnect" will then have instructions for
removing the default route (e.g. "/sbin/route del default"), for
removing all outgoing telephone numbers (e.g. "/sbin/isdnctrl delnum
isdn0 out 555-1234"), and for hanging up (e.g. "/sbin/isdnctrl hangup
isdn0").
I provided some sample scripts in the directory "sample". These
scripts make use of more advanced features and demonstrate how you can
configure ISDN-button for unusual environments. You will have to edit
these files before you can use them, but they should give you a couple
of hints.
You will notice, that most of the examples have more than just a
"connect" and a "disconnect" script. This is because whenever you
depress the right mouse button, ISDN-Button will scan all of the files
in the "/usr/sbin/isdn" directory for a magic signature (this
signature can appear anywhere in the file). If it finds the string
"ISDNBUTTON:", it will interpret the following words as the title for
a menu entry (note! there must be a space character after the
colon!). If the directory contains at least one file that contains
this signature, then the "connect" and "disconnect" scripts will not
be added to the menu unless they also contain a signature. (You can
can still call "connect" and "disconnect" by pressing the left mouse
button, though!)
You can use this feature to add arbitrary shell scripts to the
menu. Use alphabetically sorted filenames to determine the order in
the menu. You can even dynamically rebuild the menu when needed. The
directory gets re-scanned whenever the right mouse button is pressed.
A lot of ISDN-Button's behavior can be configured with application
resources. A sample application resource is available in
"Isdnbutton.ad", but you do not really have to install this file
unless you want to change any of the default values. Contrary to what
most other X11 applications do, you will only have to modify those
application defaults, that you want to override. "isdnbutton" knows
how to deal with partial resource files!
It is highly advisable, that you configure "syslogd" to log all
messages of priority "warn" or above. The output should not only go
into a log file, but also into either the "xconsole" window or on a
free virtual console! ISDN-button uses the facility "user". All error
messages, that are output when "dis-/connect" or any of the other
scripts is run, will be sent to "syslogd".
This program works fine, if you connect to just a limited number of
ISP's. For anything more advanced than this, you are likely to exceed
the limits of ISDN-button. If you think, you have come up with an
unusual trick for using ISDN-button in more advanced applications, I
would like to know about it. If you have sample files that should be
distributed in the "sample" directory, then please let me know.
For copyright/licensing information have a look into the header of the
C source code. Basically, this code is covered under the conditions of
the GPL, but I would really appreciate if you sent me a postcard from
your home-town, if you think that ISDN-button is useful to you.
Markus Gutschke, Schlage 5a, D-48268 Greven-Gimbte, Germany
gutschk@uni-muenster.de
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