NAME

XtitanG3 - X Window System server

SYNOPSIS

XtitanG3 [:displaynumber] [-option ...] [ttyname]

DESCRIPTION

XtitanG3 is the Kubota Pacific Titan G3 X Window System server.  It is usually invoked by the Xtitan shell script that determines which graphics board is installed on the system. The X titan G3 server is specific to  all G3 machines. 

STARTING THE SERVER

The server is started from the X Display Manager program xdm.  This utility is run from the system boot files and takes care of keeping the server running, prompting for usernames and passwords, and starting up the user sessions.  It is easily configured for sites that wish to provide nice, consistent interfaces for novice users (loading convenient sets of resources, starting up a window manager, clock, and nice selection of terminal emulator windows). 

Since xdm now handles automatic starting of the server in a portable way, the -L option to xterm is now considered obsolete.  Support for starting a login window from 4.3bsd-derived /etc/ttys files is no longer included. 

Installations that run more than one window system will still need to use the xinit utility.  However, xinit is to be considered a tool for building startup scripts and is not intended for use by end users.  Site administrators are strongly urged to build nicer interfaces for novice users. 

When the server starts up, it takes over the display.  If you are running on a workstation whose console is the display, you cannot log into the console while the server is running. 

NETWORK CONNECTIONS

The server supports connections made using the following reliable byte-streams:

TCP/IP
The server listens on port htons(6000+n), where n is the display number. 

Unix Domain
The server uses /tmp/.X11-unix/Xn as the filename for the socket, where n is the display number. 

DECnet
The server responds to connections to object X$Xn, where n is the display number.  This is not supported in all environments. 

OPTIONS

The server will accept the following command line options:

−a number
sets pointer acceleration (i.e. the ratio of how much is reported to how much the user actually moved the pointer).

−auth authorization-file
Specifies a file which contains a collection of authorization records used to authenticate access.

bc disables certain kinds of error checking, for bug compatibility with previous releases (e.g., to work around bugs in R2 and R3 xterms and toolkits).  Deprecated. 

−bs disables backing store support on all screens. 

−c turns off key-click. 

c volume sets key-click volume (allowable range: 0-100). 

-cc class sets the visual class for the root window of color screens.  The class numbers are as specified in the X protocol.  Not obeyed by all servers. 

−co filename
sets name of RGB color database.

−dpi resolution
sets the resolution of the screen, in dots per inch. To be used when the server cannot determine the screen size from the hardware.

−f volume
sets feep (bell) volume (allowable range: 0-100).

−fc cursorFont
sets default cursor font.

−fn font
sets the default font.

−fp fontPath
sets the search path for fonts.  This path is a comma separated list of directories which the server searches for font databases.

−help prints a usage message. 

−I causes all remaining command line arguments to be ignored. 

−logo turns on the X Window System logo display in the screen-saver.  There is currently no way to change this from a client. 

nologo turns off the X Window System logo display in the screen-saver.  There is currently no way to change this from a client. 

−p minutes
sets screen-saver pattern cycle time in minutes.

−r turns off auto-repeat. 

−bgr In order to achieve the best X client performance, the server should be run with the command line arguments "-cc 4 -bgr" for a BGR TrueColor default visual, or "-cc 5 bgr" for a BGR DirectColor default visual. If the server is started with a PseudoColor default visual, the -bgr flag will not affect anything. 

Applications using XPutimage or XShmPutImage must display in a window that has a colormap with a visual that matches the format of the data for the colors to be correct. E.g. if your data is stored in RGB format (where each pixel is 0x00RRGGBB) the window you sent the image to must have an RGB visual. If your data is stored in BGR format (0x00BBGGRR), the output window must have a BGR visual. 

To insure the best performace for XPutImage and XShmPutImage regardless of the default visual, applications should associate a colormap with its windows that uses the BGR visual, if it’s available. 

r turns on auto-repeat. 

−s minutes
sets screen-saver timeout time in minutes.

−su disables save under support on all screens. 

−t number
sets pointer acceleration threshold in pixels (i.e. after how many pixels pointer acceleration should take effect).

−to seconds
sets default connection timeout in seconds.

ttyxx ignored, for servers started the ancient way (from init). 

v sets video-on screen-saver preference. 

−v sets video-off screen-saver preference. 

−x extension
loads the specified extension at init.

You can also have the X server connect to xdm using XDMCP.  Although this is not typically useful as it doesn’t allow xdm to manage the server process, it can be used to debug XDMCP implementations, and servers as a sample implementation of the server side of XDMCP.  For more information on this protocol, see the XDMCP specification in docs/XDMCP/xdmcp.ms.  The following options control the behavior of XDMCP. 

−query host-name
Enable XDMCP and send Query packets to the specified host.

−broadcast
Enable XDMCP and broadcast BroadcastQuery packets to the network.  The first responding display manager will be chosen for the session.

−indirect host-name
Enable XDMCP and send IndirectQuery packets to the specified host.

−port port-num
Use an alternate port number for XDMCP packets.  Must be specified before any -query, -broadcast or -indirect options.

−once Normally, the server keeps starting sessions, one after the other.  This option makes the server exit after the first session is over. 

−class display-class
XDMCP has an additional display qualifier used in resource lookup for display-specific options.  This option sets that value, by default it is "MIT-Unspecified" (not a very useful value).

−cookie xdm-auth-bits
When testing XDM-AUTHENTICATION-1, a private key is shared between the server and the manager.  This option sets the value of that private data (not that it’s very private, being on the command line and all...).

−displayID display-id
Yet another XDMCP specific value, this one allows the display manager to identify each display so that it can locate the shared key.

−pixmap filename
This specifies the name of the background pixmap file (XWD format).

nobc Turns off backward compatibility. 

−Sg gammaValue
Gamma correction value. This option allows the user to compensate for differances in screen displays and get the same color intensity from colormap indexes.

−debug debugvalue
Debug value to be set, in hex.

−stereo Enable stereo screen mode with screen shutters, 1280x512 per eye. 

−stereo_s
Enable stereo screen mode for stereo glasses, 1280x512 per eye.

−stereo_q
Enable stereo screen mode with screen shutters, 640x512 per eye.

−stereo_sq
Enable stereo screen mode for stereo glasses, 640x512 per eye.

SECURITY

The server implements a basic authorization protocol, MIT-MAGIC-COOKIE-1 which uses data private to authorized clients and the server.  This is a rather trivial scheme; if the client passes authorization data which is the same as the server has, it is allowed access.  This scheme is worse than the host-based access control mechanisms in environments with unsecure networks as it allows any host to connect, given that it has discovered the private key.  But in many environments, this level of security is better than the host-based scheme as it allows access control per-user instead of per-host. 

In addition, the server provides support for a DES-based authorization scheme, XDM-AUTHORIZATION-1, which is more secure (given a secure key distribution mechanism), but as DES is not generally distributable, the implementation is missing routines to encrypt and decrypt the authorization data.  This authorization scheme can be used in conjunction with XDMCP’s authentication scheme, XDM-AUTHENTICATION-1 or in isolation. 

The authorization data is passed to the server in a private file named with the -auth command line option.  Each time the server is about to accept the first connection after a reset (or when the server is starting), it reads this file.  If this file contains any authorization records, the local host is not automatically allowed access to the server, and only clients which send one of the authorization records contained in the file in the connection setup information will be allowed access.  See the Xau manual page for a description of the binary format of this file.  Maintenance of this file, and distribution of its contents to remote sites for use there is left as an exercise for the reader. 

The server also uses a host-based access control list for deciding whether or not to accept connections from clients on a particular machine.  This list initially consists of the host on which the server is running as well as any machines listed in the file /etc/Xn.hosts, where n is the display number of the server.  Each line of the file should contain either an Internet hostname (e.g. expo.lcs.mit.edu) or a DECnet hostname in double colon format (e.g. hydra::).  There should be no leading or trailing spaces on any lines.  For example:

joesworkstation
corporate.company.com
star::
bigcpu::

Users can add or remove hosts from this list and enable or disable access control using the xhost command from the same machine as the server.  For example:

%  xhost +janesworkstation
janesworkstation being added to access control list
%  xhost -star::
public:: being removed from access control list
%  xhost +
all hosts being allowed (access control disabled)
%  xhost -
all hosts being restricted (access control enabled)
%  xhost
access control enabled (only the following hosts are allowed)
joesworkstation
janesworkstation
corporate.company.com
bigcpu::

Unlike some window systems, X does not have any notion of window operation permissions or place any restrictions on what a client can do; if a program can connect to a display, it has full run of the screen.  Sites that have better authentication and authorization systems (such as Kerberos) might wish to make use of the hooks in the libraries and the server to provide additional security models. 

SIGNALS

The server attaches special meaning to the following signals:

SIGHUP This signal causes the server to close all existing connections, free all resources, and restore all defaults.  It is sent by the display manager whenever the main user’s main application (usually an xterm or window manager) exits to force the server to clean up and prepare for the next user. 

SIGTERM
This signal causes the server to exit cleanly.

SIGUSR1
This signal is used quite differently from either of the above.  When the server starts, it checks to see if it has inherited SIGUSR1 as SIG_IGN instead of the usual SIG_DFL.  In this case, the server sends a SIGUSR1 to it’s parent process after it has set up the various connection schemes.  Xdm uses this feature to recognize when connecting to the server is possible.

FONTS

Fonts are usually stored as individual files in directories.  The list of directories in which the server looks when trying to open a font is controlled by the font path.  Although most sites will choose to have the server start up with the appropriate font path (using the -fp option mentioned above), it can be overridden using the xset program. 

The default font path for the server contains three directories:

/usr/lib/X11/fonts/misc
This directory contains several miscellaneous fonts that are useful on all systems.  It contains a very small family of fixed-width fonts (6x10, 6x12, 6x13, 8x13, 8x13bold, and 9x15) and the cursor font.  It also has font name aliases for the commonly used fonts fixed and variable. 

/usr/lib/X11/fonts/75dpi
This directory contains fonts contributed by Adobe Systems, Inc. and Digital Equipment Corporation and by Bitstream, Inc. for 75 dots per inch displays.  An integrated selection of sizes, styles, and weights are provided for each family.

/usr/lib/X11/fonts/100dpi
This directory contains versions of the fonts in the 75dpi directory for 100 dots per inch displays. 

Font databases are created by running the mkfontdir program in the directory containing the compiled versions of the fonts (the .snf files).  Whenever fonts are added to a directory, mkfontdir should be rerun so that the server can find the new fonts.  If mkfontdir is not run, the server will not be able to find any fonts in the directory.

DIAGNOSTICS

Too numerous to list them all.  If run from init(8), errors are logged in the file /usr/adm/X∗msgs,

FILES

/etc/X∗.hosts Initial access control list

/usr/lib/X11/fonts/misc, /usr/lib/X11/fonts/75dpi, /usr/lib/X11/fonts/100dpi
Font directories

/usr/lib/X11/rgb.txt Color database

/tmp/.X11-unix/X∗ Unix domain socket

/usr/adm/X∗msgs Error log file

SEE ALSO

X(1), Xtitan(1), XtitanG2(1), xdm(1), mkfontdir(1), xinit(1), xterm(1), mwm(1), twm(1), xhost(1), xset(1), xsetroot(1), ttys(5), init(8), Xqdss(1), Xqvss(1), Xsun(1), Xapollo(1), XmacII(1) X Window System Protocol, Definition of the Porting Layer for the X v11 Sample Server, Strategies for Porting the X v11 Sample Server, Godzilla’s Guide to Porting the X V11 Sample Server

BUGS

The option syntax is inconsistent with itself and xset(1). 

The acceleration option should take a numerator and a denominator like the protocol. 

If X dies before its clients, new clients won’t be able to connect until all existing connections have their TCP TIME_WAIT timers expire. 

The color database is missing a large number of colors.  However, there doesn’t seem to be a better one available that can generate RGB values tailorable to particular displays. 

COPYRIGHT

Copyright 1984, 1985, 1986, 1987, 1988, 1989, Massachusetts Institute of Technology. 
Copyright 1991, 1992 Kubota Pacific Computer Inc.
See X(1) for a full statement of rights and permissions. 

September 15, 1992