This section summarizes the configuration requirements of X11R4, X11R5, and X11R6 XDM on manager hosts. For more detailed information, see the X Window System Administrator's Guide from O'Reilly and Associates. For information about X11R3 XDM, see "Using XDM-X11R3 Version".

All manager hosts require:

• XDM configuration files installed. Installing XDM binaries and configuration files is an ncdinstall option, so you may have already installed the files. If you are already using XDM or you have installed files from other sources, you do not need to reinstall them.
  

• A system-wide session management file
  

• An operating XDM daemon. System files should be configured to start the daemon automatically when the host reboots
  

The following are optional on manager hosts:

• Customized XDM configuration files
  

• Access control to authorize clients to connect to the terminal
  

• Individual session management files for users
  

The xdm(1) program binary is installed in the /usr/bin/X11 directory and must be installed on each XDM manager host.

Installing XDM Configuration Files

XDM binaries and configuration files must be installed on each XDM manager host. Configuration files are installed in the /usr/lib/X11/xdm directory.

Table 8-2 lists the files on the NCDware distribution, along with the function of each file and whether it is required.

Table 8-2 XDM Binary and Configuration Files

This section describes the system-wide Xsession file, which typically performs the following functions:

• Establishes a default X session for all users who log into the host where the file is installed
  

• Checks for .xsession files in user home directories, in case the user prefers an individual X session
  

  • If .xsession files are present, the Xsession file executes them

  • If .xsession files are not present, the Xsession file defines the user's session
  
  For information about .xsession files, see the NCDware System Administrator's Guide for UNIX Systems.
  

• Invokes xrdb(1) to load client resources into the X server, where they are available for all clients. If you do not use xrdb to load resources and you have not cross-mounted user home directories, then users must have separate resource files (such as .Xdefaults) in their home directory on each host.
  
  You must use xrdb to load resources for NCD local clients into the X server; local clients do not read resource files.
  

• Starts the initial clients, including a window manager.
  

If you want to edit the default Xsession file:

1. Make sure the file permissions are correct. The Xsession file must be world-executable.
   

2. Edit the file, if necessary, following these general rules for Xsession files:
   

   • Clients that must take effect before starting subsequent clients are executed in the foreground. For example, clients such as xrdb, xset, and xmodmap run in the foreground because subsequent clients may need the output of these programs.

   • All other clients are executed in the background.

   • The last client executes in the foreground, the script exits, and the user is logged out.
   
   In NCDware, users can log out by using the Logout utility in the Console menu. If you do not want to use the Logout utility, you can use the logout method described in "The Default Xsession File".
   
   

   Note:

   If your Xsession file does not execute properly, you may not be able to log in through XDM. You must log in through the NCD Terminal Emulator. For more information about XDM troubleshooting, see the NCDware System Administrator's Guide for UNIX Systems.

   
   

The default Xsession file included on the NCDware distribution follows. Note that:

• The file is executed by the Bourne shell.
  

• The file must be world-executable.
  

• The if-then-else clause attempts to run a .xsession file in the user's home directory; if no .xsession file is found, the remaining commands in the Xsession file are executed.
  

• The file starts the twm window manager and an xterm window on the login host.
  

• The last client runs in the foreground; when the user exits from this xterm, the X session ends and the user is logged out.
  

• Using exec to start clients saves a process slot on the host.
  

  
  #!/bin/sh
  # Xsession
  if [ -f $HOME/.xsession ]; then
        if [ -x $HOME/.xsession ]; then
             exec $HOME/.xsession
        else
             exec /bin/sh $HOME/.xsession
       fi
  else
  
       exec xterm -fn 10x20 -geometry 80x24+20+20 -ls
  fi
  

The Xsession file shown in this section is designed for using the default local NCD Window Manager (ncdwm[1]). Note the following:

• The variable NCDNAME (the terminal's hostname) is extracted from the DISPLAY variable and is used later in the file in a remote shell command.
  

• By exporting NCDNAME, you can use it in other commands, for example, in the window manager's menu configuration file.
  

• The PATH variable must be correct for applications that users need to run.
  

  
  #!/bin/sh
  NCDNAME=\Qecho $DISPLAY | awk ` {FS=":"; print $1}'\Q
  PATH=.:/usr/local/bin:/usr/local/bin/X11:/usr/bin/X11:$PATH
  export NCDNAME PATH
  
  if [ -f $HOME/.xsession ]; then
       if [ -x $HOME/.xsession ]; then
               exec $HOME/.xsession
       else
               exec /bin/sh $HOME/.xsession
       fi
  else
  # Start the ncdwm local window manager
  ncdrunwm -d $NCDNAME &
  # Start an xterm
  xterm -sb -geometry 80x24-5-150 -fn 9x15bold &
  fi
  

To start the local Motif Window Manager instead of the NCD Window Manager, use the -mwm option to ncdrunwm; for example:

# Start the mwm local window manager
#
ncdrunwm -d $NCDNAME -mwm &

For OpenWindows, you can change the default Xsession file so the environment is OpenWindows or you can install user-specific .xsession files to establish the OpenWindows environment.

If you set up an Xsession file tailored for OpenWindows, only users who are not using OpenWindows should have .xsession files in their home directories. As an alternative, you can leave the default Xsession file unchanged and set up .xsession files for users who run OpenWindows.

For information about .xsession files, see the NCDware System Administrator's Guide for UNIX Systems.

The following Xsession file is designed for use with the OpenWindows environment. The script starts a command tool and the olwm window manager.

#!/bin/sh
NCDNAME = \Qecho $DISPLAY | awk ' {FS=":"; print $1} ' \Q
#
# Set up variables for running OpenWindows
OPENWINHOME=/usr/openwin
export OPENWINHOME
OW=$OPENWINHOME
export OW
LD_LIBRARY_PATH=$OW/lib:/usr/lib
MANPATH=$OW/man:/usr/man
PATH=$OW/bin:$OW/bin/xview:$OW/demo:/usr/local/bin:/usr/local/bin/X11:/u
sr/bin

export NCDNAME LD_LIBRARY_PATH MANPATH PATH

if [ -f $HOME/.xsession ]; then
     if [ -x $HOME/.xsession ]; then
               exec $HOME/.xsession
     else
               exec /bin/sh $HOME/.xsession
     fi
else
fi
#
# Start a cmdtool session
$OW/bin/cmdtool &
#
# Start OpenLook Window Manager
exec olwm

For information on creating .xsession files, see the NCDware System Administrator's Guide.

Configuring the XDM Xaccess File

The Xaccess file is used only by the X11R5 and X11R6 versions of XDM and is required on all hosts running X11R5 or X11R6 XDM. Its function is to control access to the host.

If you are using the Login Chooser, you do not need to configure this file unless the terminal is sending an indirect query and you want to configure the host's response.

The default file provided on the NCDware distribution is shown here. This file allows all terminals to connect to the host:

# XDMCP access file

*         # allow everybody

If you edit the Xaccess file while XDM is running, XDM automatically re-reads the file and uses the new information the next time a terminal connects to the host.

Contents of an Xaccess File Entry

File entries consist of hostnames, patterns, and macros:

• Hostnames are simple names or complete domain names. To omit a terminal from the list of those allowed to connect to the host, put an exclamation point (!) in front of its name.
  

• A pattern includes one or more wildcard characters, which are compared with the hostname of the terminal sending the query. The wildcard characters allowed are the asterisk (*) to match any number of characters and the question mark (?) to match any single character. For example, ncd* matches all terminals whose names begin with ncd.
  

• A macro definition consists of a macro name followed by a list of hostnames. The macro expands to these hostnames when you use it in another entry. Macro names begin with a percent sign (%). For example:
  

  
  %HOSTS  atlantic.oceans.com  pacific.oceans.com \
          antarctic.oceans.com
  

Xaccess files have two types of entries:

• Entries that control XDM's response to direct and broadcast queries
  

• Entries that control XDM's response to indirect queries
  

In all cases, XDM uses the first entry that matches the terminal name. If the terminal sends an indirect query, only indirect entries in the file can match. If the terminal sends a direct or broadcast query, only direct and broadcast entries can match.

Direct and Broadcast Entries in the Xaccess File

In a direct query, the terminal sends a request directly to a host. In a broadcast query, the terminal sends a request to all hosts on the network.

Direct and broadcast entries consist of a terminal hostname or a pattern representing one or more terminals.

The following entry permits direct and broadcast connections to this host from all terminals on the network:

*

This entry allows direct or broadcast access to this host from the terminal ncdu10:

ncdu10.oceans.com

This entry allows access from any terminal in the oceans domain:

*.oceans.com

This entry prevents direct or broadcast access by the terminal ncdu11:

!ncdu11.oceans.com

Indirect entries are forwarded to another host or list of hosts.

Indirect entries consist of terminal hostnames or patterns followed by a list of XDM manager hostnames, macros, or the keyword BROADCAST.

To force a terminal to a connect to a specific host, you can assign the terminal sending indirect queries to this host. For example:

ncdu12     atlantic.oceans.com

This entry disallows indirect access by ncdu13:

!ncdu13.oceans.com     dummy

The following example forwards queries from all terminals with names beginning with ncdu to the hosts listed in the %HOSTS macro.

%HOSTS     atlantic.oceans.com pacific.oceans.com \
           antarctic.oceans.com

ncdu*.oceans.com     %HOSTS

The xdm-config file is the master XDM configuration file. The functions of this file are to set some resources for the xdm client and specify the names and locations of all of the other configuration files XDM uses.

You can substitute your own files for the default configuration files. The following is an example.

DisplayManager.servers:         /usr/lib/X11/xdm/Xservers
DisplayManager.errorLogFile:    /usr/lib/X11/xdm/xdm-errors
DisplayManager.forwardingMode:  false
DisplayManager*resources:       /usr/lib/X11/xdm/Xresources
DisplayManager*startup:         /usr/lib/X11/xdm/Xstartup
DisplayManager*reset:           /usr/lib/X11/xdm/Xreset
DisplayManager*session:         /usr/lib/X11/xdm/Xsession
DisplayManager*pingInterval:    60
DisplayManager*pingTimeout:     720
DisplayManager.keyFile:         /usr/lib/X11/xdm/xdm-keys

Each resource in the xdm-config file has one form for setting the resource for all terminals and another for setting the resource for an individual terminal. For example, the authorize resource enables or disables user-based access control.

Note:

Instead of the colon ( : ) normally used in specifying the terminal's display name, an underscore ( _ ) is used in the xdm- config file. This is because of the colon's special meaning in resource specifications.

The two lines below disable user-based access control for all terminals and enable access control for the terminal ncdu15:

DisplayManager*authorize:              false
DisplayManager.ncdu15_0.authorize:      true

The pingInterval resource controls how often XDM polls terminals to see if they are still running. The units are minutes.

DisplayManager*pingInterval:           60
DisplayManager*pingTimeout:            720

For OpenWindows, add the following line to the xdm-config file so XDM can find the correct version of xrdb, the utility used to load client resources:

DisplayManager*xrdb: /usr/openwin/bin/xrdb

The Xresources file sets resources for clients that run before the user logs in (such as the login banner) and is read by each X server as it connects to XDM. The class name for the login prompter is xlogin.

You should edit the following entry in the file so the desired greeting is displayed in the login banner:

xlogin*greeting: your greeting

The xdm-errors file logs errors reported by XDM. It must be world-writable.