The Fedora 10 SELinux User Guide is for people with minimal or no experience with SELinux. Although system administration experience is not necessary, content in this guide is written for system administration tasks. This guide provides an introduction to fundamental concepts and practical applications of SELinux. After reading this guide you should have an intermediate understanding of SELinux.
Thank you to everyone who offered encouragement, help, and testing - it is most appreciated. Very special thanks to:
Dominick Grift, Stephen Smalley, and Russell Coker for their contributions, help, and patience.
Karsten Wade for his help, adding a component for this guide to Red Hat Bugzilla, and sorting out web hosting on http://docs.fedoraproject.org/.
The Fedora Infrastructure Team for providing hosting.
Jens-Ulrik Petersen for making sure the Red Hat Brisbane office has up-to-date Fedora mirrors.
This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information.
In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts set. The Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not, alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later includes the Liberation Fonts set by default.
Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows.
Mono-spaced Bold
Used to highlight system input, including shell commands, file names and paths. Also used to highlight key caps and key-combinations. For example:
To see the contents of the file
my_next_bestselling_novel
in your current working directory, enter thecat my_next_bestselling_novel
command at the shell prompt and press Enter to execute the command.
The above includes a file name, a shell command and a key cap, all presented in Mono-spaced Bold and all distinguishable thanks to context.
Key-combinations can be distinguished from key caps by the hyphen connecting each part of a key-combination. For example:
Press Enter to execute the command.
Press Ctrl+Alt+F1 to switch to the first virtual terminal. Press Ctrl+Alt+F7 to return to your X-Windows session.
The first sentence highlights the particular key cap to press. The second highlights two sets of three key caps, each set pressed simultaneously.
If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in Mono-spaced Bold
. For example:
File-related classes include
filesystem
for file systems,file
for files, anddir
for directories. Each class has its own associated set of permissions.
Proportional Bold
This denotes words or phrases encountered on a system, including application names; dialogue box text; labelled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example:
Choose Mouse Preferences. In the Buttons tab, click the Left-handed mouse check box and click to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand).
from the main menu bar to launchTo insert a special character into a gedit file, choose from the main menu bar. Next, choose from the Character Map menu bar, type the name of the character in the Search field and click . The character you sought will be highlighted in the Character Table. Double-click this highlighted character to place it in the Text to copy field and then click the button. Now switch back to your document and choose from the gedit menu bar.
The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in Proportional Bold and all distinguishable by context.
Note the
shorthand used to indicate traversal through a menu and its sub-menus. This is to avoid the difficult-to-follow 'Select from the sub-menu in the menu of the main menu bar' approach.
or Mono-spaced Bold Italic
Proportional Bold Italic
Whether Mono-spaced Bold or Proportional Bold, the addition of Italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example:
To connect to a remote machine using ssh, type
ssh
at a shell prompt. If the remote machine isusername
@domain.name
example.com
and your username on that machine is john, typessh john@example.com
.The
mount -o remount
command remounts the named file system. For example, to remount thefile-system
/home
file system, the command ismount -o remount /home
.To see the version of a currently installed package, use the
rpm -q
command. It will return a result as follows:package
.
package-version-release
Note the words in bold italics above — username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system.
Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example:
When the Apache HTTP Server accepts requests, it dispatches child processes or threads to handle them. This group of child processes or threads is known as a server-pool. Under Apache HTTP Server 2.0, the responsibility for creating and maintaining these server-pools has been abstracted to a group of modules called Multi-Processing Modules (MPMs). Unlike other modules, only one module from the MPM group can be loaded by the Apache HTTP Server.
Two, commonly multi-line, data types are set off visually from the surrounding text.
Output sent to a terminal is set in Mono-spaced Roman
and presented thus:
books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs
Source-code listings are also set in Mono-spaced Roman
but are presented and highlighted as follows:
package org.jboss.book.jca.ex1; import javax.naming.InitialContext; public class ExClient { public static void main(String args[]) throws Exception { InitialContext iniCtx = new InitialContext(); Object ref = iniCtx.lookup("EchoBean"); EchoHome home = (EchoHome) ref; Echo echo = home.create(); System.out.println("Created Echo"); System.out.println("Echo.echo('Hello') = " + echo.echo("Hello")); } }
Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.
A note is a tip or shortcut or alternative approach to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier.
Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring Important boxes won't cause data loss but may cause irritation and frustration.
A Warning should not be ignored. Ignoring warnings will most likely cause data loss.