Fedora Linux

The remaining lines listed start character-mode logins on virtual terminals 1 through 6; the respawn keyword indicates that init must restart those programs when they terminate, enabling another user to log in.

4.5.3. What About...

4.5.3.1. ...booting without an /etc/inittab file?

If the file /etc/inittab doesn't exist, init cannot start the system normally. Runlevel S was created specifically for this purpose; it's the only runlevel that doesn't require /etc/inittab , so it can be a lifesaver if that file is missing or messed up. In fact, init doesn't even ask for a password in runlevel S; it takes you directly to a root command prompt. This is useful if you've forgotten the root password, but presents a huge security risk.

To protect against the unauthorized use of runlevel S, it's a good idea to add a password entry to the boot menu. If you didn't do this during the installation, you can add the password at any time by following these steps:

1. Generate an encrypted password with the grub-md5-crypt command:

2. $ grub-md5-crypt
3. Password:
4. bigsecret
5. Retype password:
6. bigsecret  $1$f1z061$j/UEYyBn0e0996w0gjq4k/
7.

8. The previous line in bold is the encrypted (scrambled) version of the password.

9. Next, edit the /boot/grub/grub.conf file and add this line at the top, substituting the password generated in step 1:

10. password --md5 $1$f1z061$j/UEYyBn0e0996w0gjq4k/
11.

12. When you boot the system, you will still be able to select a boot menu entry, but to perform any advanced operations (such as appending runlevel information to a boot entry) you will need to enter the password.

4.5.3.2. ...using the GUI in runlevel 3?

Just because runlevel 3 doesn't offer a graphical login screen doesn't mean that you can't use a graphical user interface. If you log in on a character-mode display, you can start the GUI with this command:

$ startx

To have the GUI start each time you log in, add this command to your ~/.bash_profile :

exec startx

On a server, this gives you the best of both worlds: the GUI doesn't consume any resources when it's not in use, but it can be started quickly any time you need ituseful when you need to look up documentation on a web site, for example.

4.5.4. Where Can I Learn More?

? The manpages for init and inittab

4.6. Managing and Configuring Services

Fedora starts a number of programs automatically when the system is booted. These services (sometimes called Disk And Execution MONitors , or daemons ) perform automatic actions on the local computer and, in some cases, perform operations for remote computers on the network, such as sharing files and serving web pages.

Each service consumes memory and processor time, and each network service may provide a weak spot for an attack against your system. Disabling unused services can reduce your boot time, speed up your system, and reduce your security risk.

4.6.1. How Do I Do That?

Select the menu option System>Administration>Services (in KDE, it is System>Services) to start the system-config-services tool, shown in Figure 4-6.

Figure 4-6. Services configuration window

The configuration of the current runlevel is shown by default. Every service with a checkmark in front of it will be started when that runlevel is entered; to add or clear a checkmark, click on the checkbox.

Click on a service name to see a description of that service and its current status ( running or stopped ). Click on the Save icon (or File>Save Changes) when you've configured the services to your liking; your changes will take effect next time you change runlevels or boot the system.

You can edit the settings for another runlevel (3, 4, 5, or all three at the same time) using options on the Edit Runlevel menu.

To start, stop, or restart a service immediately, regardless of whether it's configured to start automatically at boot time, click on the service name and then click on the Start, Stop, or Restart icon.