Certification
X Window System UNIT 9
X Window System
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. UNIT 9: Objectives
Upon completion of this unit you should be able to:
? Describe the X architecture
? Configure X
? Configure X security
? Describe how X manages and displays fonts
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. UNIT 9: Agenda
? X concepts and architecture
? Configuring X
? X security concepts
? Fonts in X
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. The X Window System
? Provides foundation for the graphical component of Linux
? Created in 1984, still used today
? Solid, extensible, modular design
? Client / Server Architecture
? XFree86 - Free Open Source implementation of X
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. The X Protocol
? X applications communicate with a display via the X protocol
? X is OS independent
? Available on many platforms
? The history of the X protocol
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. Network-Transparent
? The X protocol can be sent over TCP/IP
? Enables applications to run and use resources on one computer while displaying and accepting keyboard and mouse input from another computer
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. X Security
? X is a network service, and thus raises security issues
? Host-based security is implemented through the xhost command
? User-based security is implemented through the Xauthority mechanism
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. xauth with ssh
? ssh automatically installs xauth keys on remote machine
? Tunnels X protocol over secure encrypted ssh connection
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. X Modularity
? Core components can be replaced with customized or improved programs
? Different graphical logins -- gdm, kdm, xdm
? Different desktop environments
? Different window managers
? Different widget sets
? This allows X to be easily modified
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. Window Managers
?Window Managers
? Special X clients
? Perform window movement, resizing, focus
? Decorates applications
? minimize, maximize, restore buttons
? title bar
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. Display Managers
? Display managers provide local and remote X-based login capability
? Red Hat Linux provides a choice of three display managers: gdm (GNOME display manager), kdm (KDE display manager), and xdm (X display manager)
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. XFree86 Startup (startx)
?startx used from a virtual console prompt
?/etc/X11/xinit/xinitrc runs unless ~/.xinitrc exists, in which case ~/.xinitrc will run instead
?xinitrc runs all executables in /etc/X11/xinit/xinitrc.d/ ?xinitrc determines desktop environment to run ? if user has a ~/.Xclients file, use that ? else, run /etc/X11/xinit/Xclients ? Xclients reads /etc/sysconfig/desktop to determine the preferred desktop environment
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. XFree86 Startup (prefdm)
?/etc/X11/prefdm starts the display manager ?/etc/X11/xdm/Xsetup_0 is run as root before the login window ("greeter") starts ?/etc/X11/xdm/Xsession runs as user after login ? runs all executables in /etc/X11/xinit/xinitrc.d/ ?Xsession determines desktop environment to run ? if display manager specified one, use that ? else look in user's ~/.xsession or ~/.Xclients ? if all else fails, run /etc/X11/xinit/Xclients like startx
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. Extensibility
? X is extensible by design
? Some notable X server extensions
? SHAPE
? DGA
? LBX
? DPMS
? GLX
? Xinerama
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. X Server Configuration
?Configuration ? During system installation ? After system installation ? Configuration file: /etc/X11/XF86Config
?Utilities ? redhat-config-xfree86 ? xf86config ?Documentation: /usr/X11R6/lib/X11/doc
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. X Server Design
?Server Components: ? /usr/X11R6/bin/XFree86 ? Dynamically Loadable Modules ? drivers: ati, s3virge, neomagic, fbdev, etc. ? extensions: glx, dri, etc.
?Configuration File Syntax ? ServerLayout ? Module ? InputDevice ? Monitor, Device, Screen
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. The X Font Server
?xfs is the XFree86 font server ? Configuration file /etc/X11/fs/config ? X-enabled Red Hat Linux systems run their own font servers ?Font servers can be network-enabled
? Individual workstations need not archive large amounts of fonts locally ? Centralized font management ? Default xfs configuration allows only localhost
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc. End of Unit 9
· Questions and answers · Summary · What properties does the X Window System have? · What tools are available for configuring XFree86? · What purpose does xfs serve?
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Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc.