wdm(1x)
NAME
wdm - WINGs Display Manager
SYNOPSIS
wdm [ options ]
DESCRIPTION
wdm is an X display manager based on the original X11 X Display Manager (xdm). It features numerous functionality improvements, including the ability to reboot or halt the machine (once the proper password has been supplied) and to select from a list of available X sessions to start. The look of the login panel is somewhat configurable, too.
OPTIONS
Except for -config, all of these options can be specified as resources.
-config configuration_file
Names the configuration file, which specifies resources to
control the behavior of wdm. #configdir#/wdm-config is the
default.
-nodaemon
Specifies ``false'' as the value for the
DisplayManager.daemonMode resource. This suppresses the normal
daemon behavior, which is for wdm to close all file descriptors,
disassociate itself from the controlling terminal, and put
itself in the background when it first starts up.
-debug debug_level
Specifies the numeric value for the DisplayManager.debugLevel
resource. A non-zero value causes wdm to print lots of
debugging statements to the terminal; it also disables the
DisplayManager.daemonMode resource, forcing wdm to run
synchronously. To interpret these debugging messages, a copy of
the source code for wdm is almost a necessity. No attempt has
been made to rationalize or standardize the output.
-error error_log_file
Specifies the value for the DisplayManager.errorLogFile
resource. This file contains errors from wdm as well as
anything written to stderr by the various scripts and programs
run during the progress of the session.
-syslog facility
Specifies the value for the DisplayManager.syslogFacility
resource. This is factility to use with all messages if log is
redirected to syslog.
-usesyslog
Specifies ``true'' as the value for the DisplayManager.useSyslog
resource. This will force all messages go to syslog with
facility specified by DisplayManager.syslogFacility resource.
-useerrfile
Specifies ``false'' as the value for the
DisplayManager.useSyslog resource. This will force all messages
go to log file specified by DisplayManager.errorLogFile
resource.
-resources resource_file
Specifies the value for the DisplayManager*resources resource.
This file is loaded using xrdb to specify configuration
parameters for the authentication widget.
-server server_entry
Specifies the value for the DisplayManager.servers resource.
-udpPort port_number
Specifies the value for the DisplayManager.requestPort resource.
This sets the port-number which wdm will monitor for XDMCP
requests. As XDMCP uses the registered well-known UDP port 177,
this resource should not be changed except for debugging. If set
to 0 wdm will not listen for XDMCP or Chooser requests.
-session session_program
Specifies the value for the DisplayManager*session resource.
This indicates the program to run as the session after the user
has logged in.
-xrm resource_specification
Allows an arbitrary resource to be specified, as in most X
Toolkit applications.
RESOURCES
At many stages the actions of wdm can be controlled through the use of
its configuration file, which is in the X resource format. Some
resources modify the behavior of wdm on all displays, while others
modify its behavior on a single display. Where actions relate to a
specific display, the display name is inserted into the resource name
between ``DisplayManager'' and the final resource name segment.
For local displays, the resource name and class are as read from the
Xservers file.
For remote displays, the resource name is what the network address of
the display resolves to. See the removeDomain resource. The name must
match exactly; wdm is not aware of all the network aliases that might
reach a given display. If the name resolve fails, the address is used.
The resource class is as sent by the display in the XDMCP Manage
request.
Because the resource manager uses colons to separate the name of the
resource from its value and dots to separate resource name parts, wdm
substitutes underscores for both dots and colons when generating the
resource name. For example, DisplayManager.expo_x_org_0.startup is the
name of the resource which defines the startup shell file for the
``expo.x.org:0'' display.
DisplayManager.servers
This resource either specifies a file name full of server
entries, one per line (if the value starts with a slash), or a
single server entry. See the section Local Server Specification
for the details.
DisplayManager.requestPort
This indicates the UDP port number which wdm uses to listen for
incoming XDMCP requests. Unless you need to debug the system,
leave this with its default value of 177.
DisplayManager.errorLogFile
Error output is normally directed at the system console. To
redirect it, set this resource to a file name. A method to send
these messages to syslog should be developed for systems which
support it; however, the wide variety of interfaces precludes
any system-independent implementation. This file also contains
any output directed to stderr by the Xsetup, Xstartup, Xsession
and Xreset files, so it will contain descriptions of problems in
those scripts as well.
DisplayManager.debugLevel
If the integer value of this resource is greater than zero,
reams of debugging information will be printed. It also
disables daemon mode, which would redirect the information into
the bit-bucket, and allows non-root users to run wdm, which
would normally not be useful.
DisplayManager.daemonMode
Normally, wdm attempts to make itself into a daemon process
unassociated with any terminal. This is accomplished by forking
and leaving the parent process to exit, then closing file
descriptors and releasing the controlling terminal. In some
environments this is not desired (in particular, when
debugging). Setting this resource to ``false'' will disable
this feature.
DisplayManager.pidFile
The filename specified will be created to contain an ASCII
representation of the process-id of the main wdm process. Xdm
also uses file locking on this file to attempt to eliminate
multiple daemons running on the same machine, which would cause
quite a bit of havoc.
DisplayManager.lockPidFile
This is the resource which controls whether wdm uses file
locking to keep multiple display managers from running amok. On
System V, this uses the lockf library call, while on BSD it uses
flock.
DisplayManager.authDir
This names a directory under which wdm stores authorization
files while initializing the session. The default value is
#configdir#. Can be overridden for specific displays by
DisplayManager.DISPLAY.authFile.
DisplayManager.autoRescan
This boolean controls whether wdm rescans the configuration,
servers, access control and authentication keys files after a
session terminates and the files have changed. By default it is
``true.'' You can force wdm to reread these files by sending a
SIGHUP to the main process.
DisplayManager.removeDomainname
When computing the display name for XDMCP clients, the name
resolver will typically create a fully qualified host name for
the terminal. As this is sometimes confusing, wdm will remove
the domain name portion of the host name if it is the same as
the domain name of the local host when this variable is set. By
default the value is ``true.''
DisplayManager.keyFile
XDM-AUTHENTICATION-1 style XDMCP authentication requires that a
private key be shared between wdm and the terminal. This
resource specifies the file containing those values. Each entry
in the file consists of a display name and the shared key. By
default, wdm does not include support for XDM-AUTHENTICATION-1,
as it requires DES which is not generally distributable because
of United States export restrictions.
DisplayManager.accessFile
To prevent unauthorized XDMCP service and to allow forwarding of
XDMCP IndirectQuery requests, this file contains a database of
hostnames which are either allowed direct access to this
machine, or have a list of hosts to which queries should be
forwarded to. The format of this file is described in the
section XDMCP Access Control.
DisplayManager.exportList
A list of additional environment variables, separated by white
space, to pass on to the Xsetup, Xstartup, Xsession, and Xreset
programs.
DisplayManager.randomFile
A file to checksum to generate the seed of authorization keys.
This should be a file that changes frequently. The default is
/dev/urandom.
DisplayManager.greeterLib
On systems that support a dynamically-loadable greeter library,
the name of the library. The default is
/usr/lib/X11/xdm/libXdmGreet.so. This not used in Debian.
DisplayManager.choiceTimeout
Number of seconds to wait for display to respond after user has
selected a host from the chooser. If the display sends an XDMCP
IndirectQuery within this time, the request is forwarded to the
chosen host. Otherwise, it is assumed to be from a new session
and the chooser is offered again. Default is 15.
DisplayManager.sourceAddress
Use the numeric IP address of the incoming connection on
multihomed hosts instead of the host name. This is to avoid
trying to connect on the wrong interface which might be down at
this time.
DisplayManager.willing
This specifies a program which is run (as) root when an an XDMCP
BroadcastQuery is received and this host is configured to offer
XDMCP display management. The output of this program may be
displayed on a chooser window. If no program is specified, the
string Willing to manage is sent.
DisplayManager.DISPLAY.resources
This resource specifies the name of the file to be loaded by
xrdb as the resource database onto the root window of screen 0
of the display. The Xsetup program, the Login widget, and
chooser will use the resources set in this file. This resource
data base is loaded just before the authentication procedure is
started, so it can control the appearance of the login window.
See the section Authentication Widget, which describes the
various resources that are appropriate to place in this file.
There is no default value for this resource, but
#configdir#/Xresources is the conventional name.
DisplayManager.DISPLAY.chooser
Specifies the program run to offer a host menu for Indirect
queries redirected to the special host name CHOOSER.
/usr/lib/X11/xdm/chooser is the default. See the sections XDMCP
Access Control and Chooser.
DisplayManager.DISPLAY.xrdb
Specifies the program used to load the resources. By default,
wdm uses /usr/bin/xrdb.
DisplayManager.DISPLAY.cpp
This specifies the name of the C preprocessor which is used by
xrdb.
DisplayManager.DISPLAY.setup
This specifies a program which is run (as root) before offering
the Login window. This may be used to change the appearance of
the screen around the Login window or to put up other windows
(e.g., you may want to run xconsole here). By default, no
program is run. The conventional name for a file used here is
Xsetup. See the section Setup Program.
DisplayManager.DISPLAY.startup
This specifies a program which is run (as root) after the
authentication process succeeds. By default, no program is run.
The conventional name for a file used here is Xstartup. See the
section Startup Program.
DisplayManager.DISPLAY.session
This specifies the session to be executed (not running as root).
By default, /usr/bin/x-terminal-emulator is run. The
conventional name is Xsession. See the section Session Program.
DisplayManager.DISPLAY.reset
This specifies a program which is run (as root) after the
session terminates. By default, no program is run. The
conventional name is Xreset. See the section Reset Program.
DisplayManager.DISPLAY.openDelay
DisplayManager.DISPLAY.openRepeat
DisplayManager.DISPLAY.openTimeout
DisplayManager.DISPLAY.startAttempts
These numeric resources control the behavior of wdm when
attempting to open intransigent servers. openDelay is the
length of the pause (in seconds) between successive attempts,
openRepeat is the number of attempts to make, openTimeout is the
amount of time to wait while actually attempting the open (i.e.,
the maximum time spent in the connect(2) system call) and
startAttempts is the number of times this entire process is done
before giving up on the server. After openRepeat attempts have
been made, or if openTimeout seconds elapse in any particular
attempt, wdm terminates and restarts the server, attempting to
connect again. This process is repeated startAttempts times, at
which point the display is declared dead and disabled. Although
this behavior may seem arbitrary, it has been empirically
developed and works quite well on most systems. The default
values are 5 for openDelay, 5 for openRepeat, 30 for openTimeout
and 4 for startAttempts.
DisplayManager.DISPLAY.pingInterval
DisplayManager.DISPLAY.pingTimeout
To discover when remote displays disappear, wdm occasionally
pings them, using an X connection and XSync calls. pingInterval
specifies the time (in minutes) between each ping attempt,
pingTimeout specifies the maximum amount of time (in minutes) to
wait for the terminal to respond to the request. If the
terminal does not respond, the session is declared dead and
terminated. By default, both are set to 5 minutes. If you
frequently use X terminals which can become isolated from the
managing host, you may wish to increase this value. The only
worry is that sessions will continue to exist after the terminal
has been accidentally disabled. wdm will not ping local
displays. Although it would seem harmless, it is unpleasant
when the workstation session is terminated as a result of the
server hanging for NFS service and not responding to the ping.
DisplayManager.DISPLAY.terminateServer
This boolean resource specifies whether the X server should be
terminated when a session terminates (instead of resetting it).
This option can be used when the server tends to grow without
bound over time, in order to limit the amount of time the server
is run. The default value is ``false.''
DisplayManager.DISPLAY.userPath
Xdm sets the PATH environment variable for the session to this
value. It should be a colon separated list of directories; see
sh(1) for a full description. ``:/bin:/usr/bin:/usr/games'' is
a common setting. The default value can be specified at build
time in the X system configuration file with DefaultUserPath.
DisplayManager.DISPLAY.systemPath
Xdm sets the PATH environment variable for the startup and reset
scripts to the value of this resource. The default for this
resource is specified at build time by the DefaultSystemPath
entry in the system configuration file; ``/etc:/bin:/usr/bin''
is a common choice. Note the absence of ``.'' from this entry.
This is a good practice to follow for root; it avoids many
common Trojan Horse system penetration schemes.
DisplayManager.DISPLAY.systemShell
Xdm sets the SHELL environment variable for the startup and
reset scripts to the value of this resource. It is /bin/sh by
default.
DisplayManager.DISPLAY.failsafeClient
If the default session fails to execute, wdm will fall back to
this program. This program is executed with no arguments, but
executes using the same environment variables as the session
would have had (see the section Session Program). By default,
/usr/bin/x-terminal-emulator is used.
DisplayManager.DISPLAY.grabServer
DisplayManager.DISPLAY.grabTimeout
To improve security, wdm grabs the server and keyboard while
reading the login name and password. The grabServer resource
specifies if the server should be held for the duration of the
name/password reading. When ``false,'' the server is ungrabbed
after the keyboard grab succeeds, otherwise the server is
grabbed until just before the session begins. The default is
``false.'' The grabTimeout resource specifies the maximum time
wdm will wait for the grab to succeed. The grab may fail if
some other client has the server grabbed, or possibly if the
network latencies are very high. This resource has a default
value of 3 seconds; you should be cautious when raising it, as a
user can be spoofed by a look-alike window on the display. If
the grab fails, wdm kills and restarts the server (if possible)
and the session.
DisplayManager.DISPLAY.authorize
DisplayManager.DISPLAY.authName
authorize is a boolean resource which controls whether wdm
generates and uses authorization for the local server
connections. If authorization is used, authName is a list of
authorization mechanisms to use, separated by white space.
XDMCP connections dynamically specify which authorization
mechanisms are supported, so authName is ignored in this case.
When authorize is set for a display and authorization is not
available, the user is informed by having a different message
displayed in the login widget. By default, authorize is
``true.'' authName is ``MIT-MAGIC-COOKIE-1,'' or, if XDM-
AUTHORIZATION-1 is available, ``XDM-AUTHORIZATION-1 MIT-MAGIC-
COOKIE-1.''
DisplayManager.DISPLAY.authFile
This file is used to communicate the authorization data from wdm
to the server, using the -auth server command line option. It
should be kept in a directory which is not world-writable as it
could easily be removed, disabling the authorization mechanism
in the server. If not specified, a name is generated from
DisplayManager.authDir and the name of the display.
DisplayManager.DISPLAY.authComplain
If set to ``false,'' disables the use of the unsecureGreeting in
the login window. See the section Authentication Widget. The
default is ``true.''
DisplayManager.DISPLAY.resetSignal
The number of the signal wdm sends to reset the server. See the
section Controlling the Server. The default is 1 (SIGHUP).
DisplayManager.DISPLAY.termSignal
The number of the signal wdm sends to terminate the server. See
the section Controlling the Server. The default is 15
(SIGTERM).
DisplayManager.DISPLAY.resetForAuth
The original implementation of authorization in the sample
server reread the authorization file at server reset time,
instead of when checking the initial connection. As wdm
generates the authorization information just before connecting
to the display, an old server would not get up-to-date
authorization information. This resource causes wdm to send
SIGHUP to the server after setting up the file, causing an
additional server reset to occur, during which time the new
authorization information will be read. The default is
``false,'' which will work for all MIT servers.
DisplayManager.DISPLAY.userAuthDir
When wdm is unable to write to the usual user authorization file
($HOME/.Xauthority), it creates a unique file name in this
directory and points the environment variable XAUTHORITY at the
created file. It uses /tmp by default.
DisplayManager.wdmLogin
Specifies the path to wdmLogin(1x)
DisplayManager.wdmWm
Is a colon separated list of window managers to use as options
in the login panel. Note that if you include the path to the
window manager, it will look ugly. You may set this resource to
None if you want only NoChange to appear.
DisplayManager.wdmLogo
Path to the logo pixmap, several formats are accepted, read
wdmLogin(1x) to find out more.
DisplayManager.wdmHelpFile
Path to a text file which will be displayed in the help panel,
read wdmLogin(1x) to find out more.
DisplayManager.wdmDefaultUser
a default username which will be used if no username is typed.
DisplayManager.wdmDefaultPasswd
the clear text password of the default user above. BE VERY
CAREFUL when using this two resources, and don't forget to do:
chmod 600 wdm-config ; chown root.root wdm-config
DisplayManager.wdmBg
Background specification. Read the BACKGROUND IMAGE
SPECIFICATION section to find out about the format. If this is
not specified, then the background is not set.
DisplayManager.wdmReboot
Reboot command.
DisplayManager.wdmHalt
Halt command.
DisplayManager.wdmVerify
If true, verify user's identity for reboot/halt/exit.
DisplayManager.wdmRoot
If true, user must be root to exit.
DisplayManager.wdmAnimations
If true, enable animations consisting of shaking the panel (if
an error) and rolling up the panel (when closing it). If false,
animations are disabled.
DisplayManager.wdmLocale
LANG environment variable will be set to value of this resource
before starting wdmLogin.
DisplayManger.wdmCursorTheme
If you have recent version of XFree with support for transparent
cursors you can select cursor theme to use on login panel.
XCURSOR_THEME environment variable will be set to value of this
resource before starting wdmLogin.
CONFIGURATION FILE
The default location of the wdm configuration file is #configdir#/wdm-
config
Here is a reasonable configuration file, which could be named wdm-
config:
DisplayManager.servers: /usr/lib/X11/xdm/Xservers
DisplayManager.errorLogFile: /usr/lib/X11/xdm/xdm-errors
DisplayManager*resources: /usr/lib/X11/xdm/Xresources
DisplayManager*startup: /usr/lib/X11/xdm/Xstartup
DisplayManager*session: /usr/lib/X11/xdm/Xsession
DisplayManager.pidFile: /usr/lib/X11/xdm/xdm-pid
DisplayManager._0.authorize: true
DisplayManager*authorize: false
Note that this file mostly contains references to other files. Note
also that some of the resources are specified with ``*'' separating the
components. These resources can be made unique for each different
display, by replacing the ``*'' with the display-name, but normally
this is not very useful. See the Resources section for a complete
discussion. If the entry is a host name, all comparisons are done
using network addresses, so any name which converts to the correct
network address may be used. For patterns, only canonical host names
are used in the comparison, so ensure that you do not attempt to match
aliases. Preceding either a host name or a pattern with a `!'
character causes hosts which match that entry to be excluded.
To only respond to Direct queries for a host or pattern, it can be
followed by the optional ``NOBROADCAST'' keyword. This can be used to
prevent an wdm server from appearing on menus based on Broadcast
queries.
An Indirect entry also contains a host name or pattern, but follows it
with a list of host names or macros to which indirect queries should be
sent.
A macro definition contains a macro name and a list of host names and
other macros that the macro expands to. To distinguish macros from
hostnames, macro names start with a `%' character. Macros may be
nested.
Indirect entries may also specify to have wdm run chooser to offer a
menu of hosts to connect to. See the section Chooser.
When checking access for a particular display host, each entry is
scanned in turn and the first matching entry determines the response.
Direct and Broadcast entries are ignored when scanning for an Indirect
entry and vice-versa.
Blank lines are ignored, `#' is treated as a comment delimiter causing
the rest of that line to be ignored, and `\newline' causes the newline
to be ignored, allowing indirect host lists to span multiple lines.
Here is an example Xaccess file:
#
# Xaccess - XDMCP access control file
#
#
# Direct/Broadcast query entries
#
!xtra.lcs.mit.edu # disallow direct/broadcast service for xtra
bambi.ogi.edu # allow access from this particular display
*.lcs.mit.edu # allow access from any display in LCS
*.deshaw.com NOBROADCAST # allow only direct access
*.gw.com # allow direct and broadcast
#
# Indirect query entries
#
%HOSTS expo.lcs.mit.edu xenon.lcs.mit.edu \
excess.lcs.mit.edu kanga.lcs.mit.edu
extract.lcs.mit.edu xenon.lcs.mit.edu #force extract to contact xenon
!xtra.lcs.mit.edu dummy #disallow indirect access
*.lcs.mit.edu %HOSTS #all others get to choose
RESOURCES FILE
The Xresources file is loaded onto the display as a resource database
using xrdb. As the authentication widget reads this database before
starting up, it usually contains parameters for that widget:
xlogin*login.translations: #override\
Ctrl<Key>R: abort-display()\n\
<Key>F1: set-session-argument(failsafe) finish-field()\n\
<Key>Return: set-session-argument() finish-field()
xlogin*borderWidth: 3
xlogin*greeting: CLIENTHOST
#ifdef COLOR
xlogin*greetColor: CadetBlue
xlogin*failColor: red
#endif
Please note the translations entry; it specifies a few new translations
for the widget which allow users to escape from the default session
(and avoid troubles that may occur in it). Note that if #override is
not specified, the default translations are removed and replaced by the
new value, not a very useful result as some of the default translations
are quite useful (such as ``<Key>: insert-char ()'' which responds to
normal typing).
This file may also contain resources for the setup program and chooser.
SETUP PROGRAM
The Xsetup file is run after the server is reset, but before the Login
window is offered. The file is typically a shell script. It is run as
root, so should be careful about security. This is the place to change
the root background or bring up other windows that should appear on the
screen along with the Login widget.
In addition to any specified by DisplayManager.exportList, the
following environment variables are passed:
DISPLAY the associated display name
PATH the value of DisplayManager.DISPLAY.systemPath
SHELL the value of DisplayManager.DISPLAY.systemShell
XAUTHORITY may be set to an authority file
Note that since wdm grabs the keyboard, any other windows will not be
able to receive keyboard input. They will be able to interact with the
mouse, however; beware of potential security holes here. If
DisplayManager.DISPLAY.grabServer is set, Xsetup will not be able to
connect to the display at all. Resources for this program can be put
into the file named by DisplayManager.DISPLAY.resources.
Here is a sample Xsetup script:
#!/bin/sh
# Xsetup_0 - setup script for one workstation
xcmsdb < /usr/local/lib/monitors/alex.0
xconsole -geometry 480x130-0-0 -notify -verbose -exitOnFail &
BACKGROUND IMAGE SPECIFICATION
There are several possible ways of specifying a background image. The
generic format is type:image. type can be any of:
none The backgound is not set.
solid it renders a solid background, and image is a color name
hgradient, vgradient, dgradient
a gradient (either horizontal, vertical or diagonal) will be
rendered. image is comma separated of color names, and any
number of colors can be specified.
pixmap a pixmap will be used for the background. image is the full path
to an image file (tiff, png, jpeg and xpm allowed) and it will
be scaled to use the full screen.
SEE ALSO
wdmLogin(1x)
AUTHOR
wdm was written by Gene Czarcinski <genec@mindspring.com>. wdm is based
on work by Tom Rothamel and xdm, (c) 1988 X Consortium
This man page was written by Marcelo Magallon <mmagallo@debian.org> and
extensively modified by Noah Meyerhans <noahm@debian.org>. Much of the
content was taken from xdm's manual page.
July 2002 wdm(1x)
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