[all variants] XDM client setup [Archive]

JRV

December 4th, 2010, 02:34 PM

1 - Download and burn mini.iso from here:

http://archive.ubuntu.com/ubuntu/dists/jaunty/main/installer-i386/current/images/netboot/

2 - Install the command line system.

3 - Execute this command:

sudo apt-get install xorg gdm

4 - Boot from a live CD and replace /etc/gdm.conf with this version of the file:

# GDM System Defaults Configuration file.
#
# This file should not be updated by hand. Since GDM 2.13.0.4, configuration
# choices in the GDM System Configuration file (/etc/gdm/gdm.conf) will
# override the default values specified in this file.
#
# If you were using an older version of GDM, your system may have the the older
# gdm.conf configuration file on the system. If so, then this file is used
# instead of the GDM Custom Configuration file for backwards support. If you
# make changes to the GDM Custom Configuration file and they seem to not be
# taking effect, this is likely the problem. Consider migrating your
# configuration to the new configuration file and removing the gdm.conf file.
#
# You can use the gdmsetup program to graphically edit the gdm.conf-custom
# file. Note that gdmsetup does not support every option in this file, just
# the most common ones that users want to change. If you feel that gdmsetup
# should support additional configuration options, please file a bug report at
# http://bugzilla.gnome.org/.
#
# If you hand-edit the GDM configuration, you should run the following command
# to get the GDM daemon to recognize the change. Any running GDM GUI programs
# will also be notified to update with the new configuration.
#
# gdmflexiserver --command="UPDATE_CONFIG <configuration key>"
#
# e.g, the "Enable" key in the "[debug]" section would be "debug/Enable".
#
# You can also run invoke-rc.d gdm reload or invoke-rc.d gdm restart
# to cause GDM to restart and re-read the new configuration settings.
# You can also restart GDM by sending a HUP or USR1 signal to the
# daemon. HUP behaves like restart and causes any user session
# started by GDM to exit immediately while USR1 behaves like
# reload and will wait until all users log out before
# restarting GDM.
#
# For full reference documentation see the GNOME help browser under
# GNOME|System category. You can also find the docs in HTML form on
# http://www.gnome.org/projects/gdm/
#
# NOTE: Some values are commented out, but show their default values. Lines
# that begin with "#" are considered comments.
#
# Have fun!

[daemon]
# Automatic login, if true the first attached screen will automatically logged
# in as user as set with AutomaticLogin key.
AutomaticLoginEnable=false
AutomaticLogin=

# Timed login, useful for kiosks. Log in a certain user after a certain amount
# of time.
TimedLoginEnable=false
TimedLogin=
TimedLoginDelay=30

# The GDM configuration program that is run from the login screen, you should
# probably leave this alone.
#Configurator=/usr/sbin/gdmsetup --disable-sound --disable-crash-dialog

# The chooser program. Must output the chosen host on stdout, probably you
# should leave this alone.
#Chooser=/usr/lib/gdm/gdmchooser

# The greeter for attached (non-xdmcp) logins. Change gdmlogin to gdmgreeter
# to get the new graphical greeter.
Greeter=/usr/lib/gdm/gdmgreeter

# The greeter for xdmcp logins, usually you want a less graphically intensive
# greeter here so it's better to leave this with gdmlogin
#RemoteGreeter=/usr/lib/gdm/gdmlogin

# Launch the greeter with an additional list of colon separated GTK+ modules.
# This is useful for enabling additional feature support e.g. GNOME
# accessibility framework. Only "trusted" modules should be allowed to minimize
# security holes
#AddGtkModules=false
# By default, these are the accessibility modules.
#GtkModulesList=gail:atk-bridge:/usr/lib/gtk-2.0/modules/libdwellmouselistener:/usr/lib/gtk-2.0/modules/libkeymouselistener

# Default path to set. The profile scripts will likely override this value.
DefaultPath=/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games
# Default path for root. The profile scripts will likely override this value.
RootPath=/usr/local/bin:/usr/local/sbin:/sbin:/usr/sbin:/bin:/usr/bin:/usr/bin/X11:/usr/games

# If you are having trouble with using a single server for a long time and want
# GDM to kill/restart the server, turn this on. On Solaris, this value is
# always true and this configuration setting is ignored.
#AlwaysRestartServer=

# User and group used for running GDM GUI applications. By default this is set
# to user "gdm" and group "gdm". This user/group should have very limited
# permissions and access to only the gdm directories and files.
User=gdm
Group=gdm

# To try to kill all clients started at greeter time or in the Init script.
# does not always work, only if those clients have a window of their own.
#KillInitClients=true
LogDir=/var/log/gdm

# Note that a post login script is run before a PreSession script. It is run
# after the login is successful and before any setup is run on behalf of the
# user.
PostLoginScriptDir=/etc/gdm/PostLogin/
PreSessionScriptDir=/etc/gdm/PreSession/
PostSessionScriptDir=/etc/gdm/PostSession/
DisplayInitDir=/etc/gdm/Init
# Distributions: If you have some script that runs an X server in say VGA
# mode, allowing a login, could you please send it to me?
FailsafeXServer=/etc/gdm/failsafeXServer
# if X keeps crashing on us we run this script. The default one does a bunch
# of cool stuff to figure out what to tell the user and such and can run an X
# configuration program.
XKeepsCrashing=/etc/gdm/XKeepsCrashing

# System command support.
#
# Reboot, Halt and suspend commands, you can add different commands separated
# by a semicolon. GDM will use the first one it can find.
RebootCommand=/sbin/shutdown -r now "Rebooted via gdm."
HaltCommand=/sbin/shutdown -h now "Shut Down via gdm."
SuspendCommand=/usr/sbin/pm-suspend
HibernateCommand=/usr/sbin/pm-hibernate

# The following options specify how GDM system commands are supported.
#
# Specify which actions are displayed in the greeter. Valid values are HALT,
# REBOOT, HIBERNATE, SUSPEND, and CUSTOM_CMD separated by semicolons.
SystemCommandsInMenu=HALT;REBOOT;HIBERNATE;SUSPEND ;CUSTOM_CMD

# Specify which actions are supported by QUERY_LOGOUT_ACTION, SET_LOGOUT_ACTION
# and SET_SAFE_LOGOUT_ACTION. Valid values are HALT, REBOOT, HIBERNATE, SUSPEND, and
# CUSTOM_CMD separated by semicolons.
AllowLogoutActions=HALT;REBOOT;HIBERNATE;SUSPEND;C USTOM_CMD

# This feature is only functional if GDM is compiled with RBAC (Role Based
# Access Control) support.
# Specify the RBAC key used to determine if the user has permission to use
# the action via QUERY_LOGOUT_ACTION, SET_LOGOUT_ACTION and
# SET_SAFE_LOGOUT_ACTION. The GDM GUI will only display the action if the
# "gdm" user has RBAC permissions to use the action. RBAC keys for multiple
# actions can be specified by separating them by semicolons. The format for
# each is "Action:RBAC key". If an action is not specified, it is assumed
# all users have permission for this action. For example:
# HALT:key.for.halt,REBOOT:key.for.reboot,[...]
RBACSystemCommandKeys=

# Probably should not touch the below this is the standard setup.
ServAuthDir=/var/lib/gdm
# This is our standard startup script. A bit different from a normal X
# session, but it shares a lot of stuff with that. See the provided default
# for more information.
BaseXsession=/etc/gdm/Xsession
# This is a directory where .desktop files describing the sessions live. It is
# really a PATH style variable since 2.4.4.2 to allow actual interoperability
# with KDM.
SessionDesktopDir=/usr/share/gdm/BuiltInSessions/:/usr/share/xsessions/:/var/lib/menu-xdg/xsessions/:/etc/dm/Sessions/
# This is the default .desktop session. One of the ones in SessionDesktopDir
DefaultSession=default.desktop
# Better leave this blank and HOME will be used. You can use syntax ~/ below
# to indicate home directory of the user. You can also set this to something
# like /tmp if you don't want the authorizations to be in home directories.
# This is useful if you have NFS mounted home directories. Note that if this
# is the home directory the UserAuthFBDir will still be used in case the home
# directory is NFS, see security/NeverPlaceCookiesOnNFS to override this
# behavior.
UserAuthDir=
# Fallback directory for writing authorization file if user's home directory
# is not writable.
UserAuthFBDir=/tmp
UserAuthFile=.Xauthority
# The X server to use if we can't figure out what else to run.
StandardXServer=/usr/X11R6/bin/X
# The maximum number of flexible X servers to run.
#FlexibleXServers=5
# And after how many minutes should we reap the flexible server if there is no
# activity and no one logged on. Set to 0 to turn off the reaping. Does not
# affect nested flexiservers.
#FlexiReapDelayMinutes=5

# The X nest command.
# Examples of valid commands (assuming installed to /usr/X11/bin:
# Xorg Xnest: /usr/X11/bin/Xnest -audit 0 -name Xnest
# Xsun Xnest: /usr/openwin/bin/Xnest -audit 0 -name Xnest -pn
# Xephyr: /usr/X11/bin/Xephyr -audit 0
Xnest=/usr/share/gdm/gdmXnestWrapper -br -audit 0
# Xsun Xnest does not support font paths (passed into Xnest -fp argument)
# that include the ":unscaled" suffix after a path name. Setting this to
# false will strip any ":unscaled" suffix from the font path. If not
# using this Xnest, the value should be true.
XnestUnscaledFontPath=true

# Automatic VT allocation. Right now only works on Linux. This way we force
# X to use specific vts. Turn VTAllocation to false if this is causing
# problems.
FirstVT=7
VTAllocation=true
# Should double login be treated with a warning (and possibility to change VT's
# on Linux and FreeBSD systems for console logins)
#DoubleLoginWarning=true
# Should a second login always resume the current session and switch VT's on
# Linux and FreeBSD systems for console logins
#AlwaysLoginCurrentSession=true

# If true then the last login information is printed to the user before being
# prompted for password. While this gives away some info on what users are on
# a system, it on the other hand should give the user an idea of when they
# logged in and if it doesn't seem kosher to them, they can just abort the
# login and contact the sysadmin (avoids running malicious startup scripts).
#DisplayLastLogin=false

# Program used to play sounds. Should not require any 'daemon' or anything
# like that as it will be run when no one is logged in yet.
SoundProgram=/usr/lib/gdmplay

# These are the languages that the console cannot handle because of font
# issues. Here we mean the text console, not X. This is only used when there
# are errors to report and we cannot start X.
# This is the default:
#ConsoleCannotHandle=am,ar,az,bn,el,fa,gu,hi,ja,ko ,ml,mr,pa,ta,zh

# This determines whether GDM will honor requests DYNAMIC requests from the
# gdmdynamic command.
#DynamicXServers=false

# This determines whether GDM will send notifications to the console.
#ConsoleNotify=true

# How long gdm should wait before it assumes a started Xserver is defunct and
# kills it. 10 seconds should be long enough for X, but Xgl may need 20 or 25.
GdmXserverTimeout=10

[security]
# Allow root to login. It makes sense to turn this off for kiosk use, when
# you want to minimize the possibility of break in.
AllowRoot=false
# Allow login as root via XDMCP. This value will be overridden and set to
# false if the /etc/default/login file exists and contains
# "CONSOLE=/dev/login", and set to true if the /etc/default/login file exists
# and contains any other value or no value for CONSOLE.
AllowRemoteRoot=false
# This will allow remote timed login.
AllowRemoteAutoLogin=false
# 0 is the most restrictive, 1 allows group write permissions, 2 allows all
# write permissions.
RelaxPermissions=1
# Check if directories are owned by logon user. Set to false, if you have, for
# example, home directories owned by some other user.
CheckDirOwner=true
# If your HOME is managed by automounter, set to true
SupportAutomount=false
# Number of seconds to wait after a failed login
#RetryDelay=1
# Maximum size of a file we wish to read. This makes it hard for a user to DoS
# us by using a large file.
#UserMaxFile=65536
# If true this will basically append -nolisten tcp to every X command line, a
# good default to have (why is this a "negative" setting? because if it is
# false, you could still not allow it by setting command line of any particular
# server). It's probably better to ship with this on since most users will not
# need this and it's more of a security risk then anything else.
# Note: Anytime we find a -query or -indirect on the command line we do not add
# a "-nolisten tcp", as then the query just wouldn't work, so this setting only
# affects truly attached sessions.
DisallowTCP=true
# By default never place cookies if we "detect" NFS. We detect NFS by
# detecting "root-squashing". It seems bad practice to place cookies on things
# that go over the network by default and thus we do not do it by default.
# Sometimes you can however use safe remote filesystems where this is OK and
# you may want to have the cookie in your home directory.
#NeverPlaceCookiesOnNFS=true
# Will cause PAM_DISALLOW_NULL_AUTHTOK to be passed as a flag to
# pam_authenticate and pam_acct_mgmt, disallowing NULL password. This setting
# will only take effect if PAM is being used by GDM. This value will be
# overridden with the value from /etc/default/login if it contains
# "PASSREQ=[YES|NO]"
#PasswordRequired=false
# Specifies the PAM Stack to use, "gdm" by default.
PamStack=gdm
# GDM allows configuration of how ut_line is set when it does utmp/wtmp and
# audit processing. If VT is being used, then ut_line will be set to the
# device associated with the VT. If the console is attached and has a device
# name specified in the [servers] section, then this value will be used.
# Otherwise the value is defaulted to the value specified in UtmpLineAttached
# for attached displays and UtmpLineRemote for remote displays. The value
# can be left empty which means that ut_line will be set to an empty value
# (if not VT and no value specified in the [servers] section. The values
# can contain "%d" which is translated to the DISPLAY value or %h which
# is translated to the hostname. The values for both keys must begin with
# "/dev/".
UtmpLineAttached=/dev/console
UtmpLineRemote=
# If true and the specified UtmpLineAttached or UtmpLineRemote does not exist,
# then create a pseudo-device filename that will be touched when the utmp
# record is updated. Creating such a psuedo-device ensures that programs
# that stat the utmp device associated with ut_line such as finger, last,
# etc. work in a reasonable way.
UtmpPseudoDevice=false

# XDMCP is the protocol that allows remote login. If you want to log into GDM
# remotely (I'd never turn this on on open network, use ssh for such remote
# usage). You can then run X with -query <thishost> to log in, or
# -indirect <thishost> to run a chooser. Look for the 'Terminal' server type
# at the bottom of this config file.
[xdmcp]
# Distributions: Ship with this off. It is never a safe thing to leave out on
# the net. Setting up /etc/hosts.allow and /etc/hosts.deny to only allow local
# access is another alternative but not the safest. Firewalling port 177 is
# the safest if you wish to have xdmcp on. Read the manual for more notes on
# the security of XDMCP.
Enable=false
# Honor indirect queries, we run a chooser for these, and then redirect the
# user to the chosen host. Otherwise we just log the user in locally.
#HonorIndirect=true
# Maximum pending requests.
#MaxPending=4
#MaxPendingIndirect=4
# Maximum open XDMCP sessions at any point in time.
#MaxSessions=16
# Maximum wait times.
#MaxWait=15
#MaxWaitIndirect=15
# How many times can a person log in from a single host. Usually better to
# keep low to fend off DoS attacks by running many logins from a single host.
# This is now set at 2 since if the server crashes then GDM doesn't know for
# some time and wouldn't allow another session.
#DisplaysPerHost=2
# The number of seconds after which a non-responsive session is logged off.
# Better keep this low.
#PingIntervalSeconds=15
# The port. 177 is the standard port so better keep it that way.
#Port=177
# Willing script, none is shipped and by default we'll send hostname system id.
# But if you supply something here, the output of this script will be sent as
# status of this host so that the chooser can display it. You could for
# example send load, or mail details for some user, or some such.
#Willing=/etc/gdm/Xwilling

[gui]
# The specific gtkrc file we use. It should be the full path to the gtkrc that
# we need. Unless you need a specific gtkrc that doesn't correspond to a
# specific theme, then just use the GtkTheme key.
#GtkRC=/usr/share/themes/Default/gtk-2.0/gtkrc

# The GTK+ theme to use for the GUI.
GtkTheme=Human
# If to allow changing the GTK+ (widget) theme from the greeter. Currently
# this only affects the standard greeter as the graphical greeter does not yet
# have this ability.
#AllowGtkThemeChange=true
# Comma separated list of themes to allow. These must be the names of the
# themes installed in the standard locations for gtk themes. You can also
# specify 'all' to allow all installed themes. These should be just the
# basenames of the themes such as 'Thinice' or 'LowContrast'.
#GtkThemesToAllow=all

# Maximum size of an icon, larger icons are scaled down.
#MaxIconWidth=128
#MaxIconHeight=128

[greeter]
# The following options for setting titlebar and setting window position are
# only useful for the standard login (gdmlogin) and are not used by the
# themed login (gdmgreeter).
#
# The standard login has a title bar that the user can move.
#TitleBar=true
# Don't allow user to move the standard login window. Only makes sense if
# TitleBar is on.
#LockPosition=false
# Set a position for the standard login window rather then just centering the
# window. If you enter negative values for the position it is taken as an
# offset from the right or bottom edge.
#SetPosition=false
#PositionX=0
#PositionY=0

# Enable the Face browser. Note that the Browser key is only used by the
# standard login (gdmlogin) program. The Face Browser is enabled in
# the Graphical greeter by selecting a theme that includes the Face
# Browser, such as happygnome-list. The other configuration values that
# affect the Face Browser (MinimalUID, DefaultFace, Include, Exclude,
# IncludeAll, GlobalFaceDir) are used by both the Standard and Themed
# greeter.
Browser=true
# The default picture in the browser.
#DefaultFace=/usr/share/pixmaps/nobody.png
# User ID's less than the MinimalUID value will not be included in the face
# browser or in the gdmselection list for Automatic/Timed login. They will not
# be displayed regardless of the settings for Include and Exclude.
MinimalUID=1000
# Users listed in Include will be included in the face browser and in the
# gdmsetup selection list for Automatic/Timed login. Users should be separated
# by commas.
#Include=
# Users listed in Exclude are excluded from the face browser and from the
# gdmsetup selection list for Automatic/Timed login. Excluded users will still
# be able to log in, but will have to type their username. Users should be
# separated by commas.
Exclude=nobody
# By default, an empty include list means display no users. By setting
# IncludeAll to true, the password file will be scanned and all users will be
# displayed except users excluded via the Exclude setting and user ID's less
# than MinimalUID. Scanning the password file can be slow on systems with
# large numbers of users and this feature should not be used in such
# environments. The setting of IncludeAll does nothing if Include is set to a
# non-empty value.
IncludeAll=true
# If user or user.png exists in this dir it will be used as his picture.
#GlobalFaceDir=/usr/share/pixmaps/faces/

# File which contains the locale we show to the user. Likely you want to use
# the one shipped with GDM and edit it. It is not a standard locale.alias
# file, although GDM will be able to read a standard locale.alias file as well.
LocaleFile=/etc/gdm/locale.conf
# Logo shown in the standard greeter.
Logo=/usr/share/pixmaps/gdmDebianLogo.xpm
# Logo shown on file chooser button in gdmsetup (do not modify this value).
#ChooserButtonLogo=/usr/share/pixmaps/gdm-foot-logo.png
# The standard greeter should shake if a user entered the wrong username or
# password. Kind of cool looking
#Quiver=true

# The Actions menu (formerly system menu) is shown in the greeter, this is the
# menu that contains reboot, shutdown, suspend, config and chooser. None of
# these is available if this is off. They can be turned off individually
# however.
#SystemMenu=true
# Configuration is available from the system menu of the greeter.
ConfigAvailable=false
# Should the chooser button be shown. If this is shown, GDM can drop into
# chooser mode which will run the xdmcp chooser locally and allow the user to
# connect to some remote host. Local XDMCP does not need to be enabled,
# however.
#ChooserButton=true

# Welcome is for all console logins and RemoteWelcome is for remote logins
# (through XDMCP).
# DefaultWelcome and DefaultRemoteWelcome set the string for Welcome to
# "Welcome" and for DefaultWelcome to "Welcome to %n", and properly translate
# the message to the appropriate language. Note that %n gets translated to the
# hostname of the machine. These default values can be overridden by setting
# DefaultWelcome and/or DefaultRemoteWelcome to false, and setting the Welcome
# and DefaultWelcome values as desired. Just make sure the strings are in
# utf-8 Note to distributors, if you wish to have a different Welcome string
# and wish to have this translated you can have entries such as
# "Welcome[cs]=Vitejte na %n".
DefaultWelcome=true
DefaultRemoteWelcome=true
#Welcome=Welcome
#RemoteWelcome=Welcome to %n

# Xinerama screen we use to display the greeter on. Not for true multihead,
# currently only works for Xinerama.
#XineramaScreen=0
# Background settings for the standard greeter:
# Type can be 0=None, 1=Image & Color, 2=Color, 3=Image
#BackgroundType=2
#BackgroundImage=
#BackgroundScaleToFit=true
# The Standard greeter (gdmlogin) uses BackgroundColor as the background
# color, while the themed greeter (gdmgreeter) uses GraphicalThemedColor
# as the background color.
BackgroundColor=#000000
GraphicalThemedColor=#000000
# XDMCP session should only get a color, this is the sanest setting since you
# don't want to take up too much bandwidth
#BackgroundRemoteOnlyColor=true

# Program to run to draw the background in the standard greeter. Perhaps
# something like an xscreensaver hack or some such.
#BackgroundProgram=
# If this is true then the background program is run always, otherwise it is
# only run when the BackgroundType is 0 (None).
#RunBackgroundProgramAlways=false
# Delay before starting background program
#BackgroundProgramInitialDelay=30
# Should the background program be restarted if it is exited.
#RestartBackgroundProgram=true
# Delay before restarting background program
#BackgroundProgramRestartDelay=30

# Show the Failsafe sessions. These are much MUCH nicer (focus for xterm for
# example) and more failsafe then those supplied by scripts so distros should
# use this rather then just running an xterm from a script.
#ShowGnomeFailsafeSession=true
#ShowXtermFailsafeSession=true
# Normally there is a session type called 'Last' that is shown which refers to
# the last session the user used. If off, we will be in 'switchdesk' mode
# where the session saving stuff is disabled in GDM
#ShowLastSession=true
# Always use 24 hour clock no matter what the locale.
#Use24Clock=auto
# Do not show any visible feedback in the password field. This is standard for
# instance in console, xdm and ssh.
#UseInvisibleInEntry=false

# These two keys are for the themed greeter (gdmgreeter). Circles is the
# standard shipped theme. If you want GDM to select a random theme from a
# list then provide a list that is delimited by /: to the GraphicalThemes
# key and set GraphicalThemeRand to true. Otherwise use GraphicalTheme
# and specify just one theme.
GraphicalTheme=Human
#GraphicalThemes=bijou/:blueswirl/:circles/:debblue-list/:debblue/:ayo/:debian-dawn/:debian-greeter/:debian/:glassfoot/:hantzley/:happygnome/:industrial/:crystal/:linsta
GraphicalThemeDir=/usr/share/gdm/themes/
GraphicalThemeRand=false

# If InfoMsgFile points to a file, the greeter will display the contents of the
# file in a modal dialog box before the user is allowed to log in.
#InfoMsgFile=
# If InfoMsgFile is present then InfoMsgFont can be used to specify the font to
# be used when displaying the contents of the file.
#InfoMsgFont=Sans 24

# If SoundOnLogin is true, then the greeter will beep when login is ready for
# user input. If SoundOnLogin is a file and the greeter finds the 'play'
# executable (see daemon/SoundProgram) it will play that file instead of just
# beeping.
#SoundOnLogin=true
SoundOnLoginFile=/usr/share/sounds/question.wav
# If SoundOnLoginSuccess, then the greeter will play a sound (as above) when a
# user successfully logs in.
#SoundOnLoginSuccess=false
#SoundOnLoginSuccessFile=
# If SoundOnLoginFailure, then the greeter will play a sound (as above) when a
# user fails to log in.
#SoundOnLoginFailure=false
#SoundOnLoginFailureFile=

# Specifies a program to be called by the greeter/login program when the
# initial screen is displayed. The purpose is to provide a hook where files
# used after login can be preloaded to speed performance for the user. The
# program will only be called once only, the first time a greeter is displayed.
# The gdmprefetch command may be used. This utility will load any libraries
# passed in on the command line, or if the argument starts with a "@"
# character, it will process the file assuming it is an ASCII file containing a
# list of libraries, one per line, and load each library in the file.
PreFetchProgram=/usr/lib/gdm/gdmprefetch @/etc/gdm/gdmprefetchlist

# The chooser is what's displayed when a user wants an indirect XDMCP session,
# or selects Run XDMCP chooser from the system menu
[chooser]
# Default image for hosts.
#DefaultHostImg=/usr/share/pixmaps/nohost.png
# Directory with host images, they are named by the hosts: host or host.png.
HostImageDir=/usr/share/hosts/
# Time we scan for hosts (well only the time we tell the user we are scanning
# actually, we continue to listen even after this has expired).
#ScanTime=4
# A comma separated lists of hosts to automatically add (if they answer to a
# query of course). You can use this to reach hosts that broadcast cannot
# reach.
Hosts=
# Broadcast a query to get all hosts on the current network that answer.
Broadcast=true
# Set it to true if you want to send a multicast query to hosts.
Multicast=false
# It is an IPv6 multicast address.It is hardcoded here and will be replaced
# when officially registered xdmcp multicast address of TBD will be available.
#Multicast_Addr=ff02::1
# Allow adding random hosts to the list by typing in their names.
#AllowAdd=true

[debug]
# This will cause GDM to send debugging information to the system log, which
# will create a LOT of output. It is not recommended to turn this on for
# normal use, but it can be useful to determine the cause when GDM is not
# working properly.
Enable=false
# This will enable debug messages for accessibilty gesture listeners into the
# syslog. This includes output about key events, mouse button events, and
# pointer motion events. This is useful for figuring out the cause of why the
# gesture listeners may not be working, but is too verbose for general debug.
Gestures=false

# Attached DISPLAY Configuration
#
[servers]
# This section defines which attached DISPLAYS should be started by GDM by
# default. You can add as many DISPLAYS as desired and they will always be
# started. The key for each entry must be a unique number that cooresponds to
# the DISPLAY number to start the X server. For a typical single-display
# machine, there will only be one entry "0" for DISPLAY ":0". The first word
# in the value corresponds to an X server definition in the "X Server
# Definitions" section of the configuration file. For example, the entry:
#
# 0=Standard
#
# Means that DISPLAY ":0" will start an X server as defined in the
# [server-Standard] section.
#
# The optional device argument is used to specify the device that is associated
# with the DISPLAY. When using Virtual Terminals (VT), this value is ignored
# and GDM will use the correct device name associated with the VT. If not
# using VT, then GDM will use the value specified by this optional argument.
# If the device argument is not defined, then GDM will use the default setting
# for attached displays defined in the UtmpLineAttached configuration option.
# For the main display (typically DISPLAY ":0"), "/dev/console" is a reasonable
# value. For other displays it is probably best to not include this argument
# unless you know the specific device associated with the DISPLAY. The device
# value can contain "%d" which is translated to the DISPLAY value or %h which
# is translated to the hostname.
#
0=Standard device=/dev/console

# Example of how to set up DISPLAY :1 to also use Standard.
#1=Standard

# If you wish to run the XDMCP chooser on the local display use the following
# line
0=Chooser

# X Server Definitions
#
# Note: Is your X server not listening to TCP requests? Refer to the
# security/DisallowTCP setting!

[server-Standard]
name=Standard server
command=/usr/X11R6/bin/X -br -audit 0
flexible=true
# Indicates that the X server should be started at a different process
# priority. Values can be any integer value accepted by the setpriority C
# library function (normally between -20 and 20) with 0 being the default. For
# highly interactive applications, -5 yields good responsiveness. The default
# value is 0 and the setpriority function is not called if the value is 0.

#priority=0

# To use this server type you should add -query host or -indirect host to the
# command line.
[server-Terminal]
name=Terminal server
# Add -terminate to make things behave more nicely
command=/usr/X11R6/bin/X -br -audit 0 -terminate
# Make this not appear in the flexible servers (we need extra params anyway,
# and terminate would be bad for xdmcp choosing). You can make a terminal
# server flexible, but not with an indirect query. If you need flexible
# indirect query server, then you must get rid of the -terminate and the only
# way to kill the flexible server will then be by Ctrl-Alt-Backspace.
flexible=false
# Do not handle this X server for attached displays.
handled=false

# To use this server type you should add -query host or -indirect host to the
# command line.
[server-Chooser]
name=Chooser server
command=/usr/X11R6/bin/X -br -audit 0
# Make this not appear in the flexible servers for now, but if you wish to
# allow a chooser server then make this true. This is the only way to make a
# flexible chooser server that behaves nicely.
flexible=true
# Run the chooser instead of the greeter. When the user chooses a machine they
# will get this same server but run with "-terminate -query hostname".
chooser=true

[customcommand]
# This section allows you specify up to 10 custom commands. Each of the
# commands can be defined by the seven parameters listed below. In each of the
# descriptions of the parameters N can take on any values between 0 and 9,
# i.e. CustomCommand0=,CustomCommand1=,...,CustomCommand9 =. The numbers
# can have gaps as long as they fit within predefined set of 10, and their
# placement order within this section and with respect to each other is
# not important.
#
# CustomCommandN, CustomCommandTextN, CustomCommandLabelN,
# CustomCommandLRLabelN, CustomCommandTooltipN, CustomCommandIsPersistentN
# and CustomCommandNoRestartN should all be defined for a given integer N,
# where N can be a number from 0-9 (if not the default values will be
# assigned except CustomCommandN for which no default exists).

# Custom command to run. Multiple commands may be specified separated by
# semicolons. GDM will use the first valid command. Examples:
# /sbin/boot*******;/usr/bin/boot*******, or
# /sbin/runupdate;/usr/local/sbin/runupdate
#
#CustomCommandN=

# Custom command dialog message that will appear on all warning dialogs.
# This will vary depending on what you want to do. Examples:
# Are you sure you want to restart system into *******?, or
# Are you sure you want do do this?
#CustomCommandTextN=

# Custom command label that will appear as stock label on buttons/menu items.
# This option can't contain any semicolon characters (i.e. ";").
# Examples:
# _*******, or
# _Update Me
#CustomCommandLabelN=

# Custom command label that will appear as stock label on radio buttons/list
# items. The underscore indicates the mnemonic used with this item. Examples:
# Restart into _*******
# Perform system _Update
#CustomCommandLRLabelN=

# Custom command tooltip. Examples
# Restarts the computer into *******
# Updates the computer software to the most recent version(s)
#CustomCommandTooltipN=

# Custom command persistence option. Setting it to true will allow this
# command to appear outside the login manager, e.g. on the desktop through
# Log Out/Shut Down dialogs. The default value is false.
#CustomCommandIsPersistentN=

# Custom command gdm/system restart option. Setting it to true will not
# restart gdm after command execution. The default commands (reboot, shut
# down) all reboot the system by default which is why the default setting
# is true.
# In addition when corresponding CustomCommandIsPersistentN option is set to
# true, setting CustomCommandNoRestartN to false will place CustomCommandN
# in the Shut Down dialog set of actions, setting it to true will place
# CustomCommandN in the Log Out dialog set of actions.
#CustomCommandNoRestartN=
#
# Example layout for more than one command:
#CustomCommand0=
#CustomCommandText0=
#CustomCommandLabel0=
#CustomCommandLRLabel0=
#CustomCommandTooltip0=
#CustomCommandIsPersistent0=
#CustomCommandNoRestart0=
#
#CustomCommand1=
#CustomCommandText1=
#CustomCommandLabel1=
#CustomCommandLRLabel1=
#CustomCommandTooltip1=
#CustomCommandIsPersistent1=
#CustomCommandNoRestart1=
#
# and so on

You will need to be root to replace the file.
I booted from a Puppy Linux live CD to replace the file.

This should do it.