Certification X Window System UNIT 9 X Window System 1 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 2 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 3 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 4 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 5 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 6 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 7 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 8 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 9 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 1 0 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) 1 1 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 1 2 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 1 3 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 1 4 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 1 5 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 1 6 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 1 7 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? 1 8 Rev RH133-9.0-1 Copyright © 2003 Red Hat, Inc..