6/29/2005 -- One of the primary tools that differentiates the Linux versions marketed by Novell (the variants of SuSE and Linux Desktop 9) from other implementations of Linux is its inclusion of YaST (Yet Another Setup Tool). This one-stop tool provides a convenient interface for virtually every aspect of system administration. Mastering this one tool can save you a great amount of time (and often frustration), as it offers a simple and convenient interface for a number of configuration tasks.

The YaST tool can be accessed through a command-line interface or an X Window application. The command-line interface, regardless of which version (there are two) of YaST you’re running, is an ncurses application. When YaST is run as an X Window application, the appearance will differ based on whether you’re using the first or second version of the tool: the first is ncurses-based and the second (YaST2) is Qt-based.

Programmers can write custom modules and add them to this interface, but the focus here will be on the default administrative tasks that it can do. The screenshots accompanying this article are from Novell Linux Desktop, but most of the same options appear in SuSE as well (with slight differences according to the version -- Professional, etc.).

Most of this discussion focuses on the YaST2 version of the tool because of its ease of use, and that’s what most people will use in an X Window System environment (which is where most administrators will typically be). Although the appearance of the text mode obviously differs from that of the graphical mode, all the choices are available in both interfaces.

Figure 1 shows the text-mode version of the tool upon startup. (You start it by typing yast in the command line.) From the command line, you can type yast –h to see the help information available. You can also type yast –l to view a list of all available modules.

In text mode, you can navigate through the menus and choices by using the arrow keys (up and down) and the Tab key to move between boxes (Alt + Tab moves you from window to window). You can also use the Space Bar to highlight items and Enter to choose them. You can press F9 to quit and F1 to bring up help.

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Figure 1. The startup view of YaST2 in text mode.

You can start the graphical mode by typing yast2 in the command line or by simply choosing it from the KDE menu or GNOME menu choices. (In KDE, choose System and then YaST; in GNOME, choose System and then Administrator Settings.) Figure 2 shows the startup view of this interface.

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Figure 2. The startup view of YaST2 in graphical mode.

Within the graphical interface, you navigate by using the mouse. You first click on a category within the left frame, and then choose an item from the right frame. You can also click on the Search button and enter a keyword to find.

Working with Software
When you choose Software in the opening left frame of the YaST2 window, a number of choices appear on the right:

• Online Update
• Install and Remove Software
• Change Source of Installation
• Installation into Directory
• Patch CD Update
• System Update

Most of these choices are self-explanatory, and the one you’ll use most often on a regular basis is Install and Remove Software. When you choose this option, the Filter drop-down menu allows you to choose what packages you want to see. If you choose Selections as your filter, you will see only the installed packages. If you choose Package Groups in the Filter drop-down menu, you’ll see all software on the installation media. If you choose Search, it searches the list of available packages from the current installation source(s) and lists any packages that match the string you’ve entered. Last, if you choose Installation Summary, you’ll see all the packages with their status marked.

After any software is copied, SuSEconfig automatically runs and finishes the installation before returning you to YaST. SuSEconfig updates your system’s configuration—most importantly, the dynamic linker runtime bindings for libraries—to make it possible to use any newly installed software without problems.

Working with Hardware
The YaST tool provides a simple interface to hardware configuration. Simply choose Hardware in the left frame, and then choose the object you want to configure in the right. Choices include such items as CD-ROM Drives, Disk Controller, Graphics Card and Monitor, Hardware Information, IDE DMA Mode, Joystick, Printer, Scanner, Select Mouse Model and Sound.

Hardware Information, as the name implies, displays information about all the devices currently configured on your system. Graphics Card and Monitor allows you to change X Window System resolution (a very important and common task). IDE DMA Mode lets you fine-tune how the IDE storage devices on your system use Direct Memory Access. Choosing the correct DMA mode can significantly improve device I/O, whereas choosing the wrong one can significantly hurt performance.

Before making any changes to any hardware, it’s highly recommended that you choose the Hardware Information option. This probes the current configuration and allows you to see the current settings of your devices, as shown in Figure 3.

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Figure 3. Hardware Information shows the current settings.

Working with System Settings
The choices beneath System offer access to a number tweaks that can help with host configuration. After System is chosen in the left frame, the selections in the right frame become:

• /etc/sysconfig Editor - This offers an easy way to access the editor and work with settings for applications, the desktop or other components.
• Boot Loader Configuration - You can choose from GRUB (the default), LILO or to not use any boot loader.
• Choose Language - Select a different language for the system.
• Create a Boot, Rescue, or Module Floppy - As the name implies, you can create an emergency disk for use should a crisis arise.
• Date and Time - Set the system date and time.
• LVM - If the lvm2 package is installed, you can configure volume settings and work with volume groups.
• Partitioner - Work directly with the disk partitions.
• Power Management - Choose the energy-saving scheme most applicable for this host.
• Powertweak Configuration - You must first install the powertweak package (not installed by default); then you can fine-tune settings available here.
• Profile Manager - Using System Configuration Profile Management (SCPM), you can switch between different system profiles as needed. SCPM is disabled during the default installation.
• Restore System - Use following a system crash.
• Runlevel Editor - Allows you to change the runlevel settings and can be run in either Simple Mode (the default) or Expert Mode for finer tuning.
• Select Keyboard Layout - Self-explanatory.
• System Backup - A graphical interface for creating .TAR archives.

Working with Networks
To obtain networking configuration information, first choose Network Devices in the left pane. Choices in the right pane can include:

• DSL
• Fax
• ISDN
• Modem
• Network Card
• Phone Answering Machine

As an example of the options available, choose Network Card. This will bring up the screen shown in Figure 4.

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Figure 4. Current settings for the network cards.

Devices already configured will appear in the bottom pane (Change), and new entries can be added at the top (Configure). Choosing Change first brings up another screen and you can add, edit and delete from here.

Working with Network Services
When you click the Network Services option in the left pane of YaST, a number of choices appear on the right. Those choices include:

• DNS and Host Name
• Host Names
• Kerberos Client
• LDAP Client
• Mail Transfer Agent
• NFS Client
• NIS Client
• NTP Client
• Network Services (inetd)
• Proxy
• Remote Administration
• Routing
• SLP Browser
• TFTP Server

The Remote Administration module allows you to configure your machine. The choices here are remarkably simple - either to allow remote administration or not (the default). If you choose to enable remote administration, the display manager must be restarted. After this is done, the machine can now be accessed and remotely administered. To administer it remotely, enter the following in a browser (replace host with the IP address of your machine): http://host:5801

A Virtual Network Session (VNS) window will open, and you’ll be prompted for a username and password. At the prompt for these items, you can click the Administration button instead and YaST will be initiated (requiring you to enter the root password).

Working with Security and Users
Just as YaST can be used for all other aspects of configuration, it can also provide an interface to your user and security settings. To work with users in the YaST tool, first choose Security and Users from the left frame. This brings up a number of choices in the right frame:

• Edit and create groups
• Edit and create users
• Firewall
• Security Settings

Select the Edit and Create Users choice, and a screen similar to that shown in Figure Five appears.

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Figure 5. Users and groups can be added and altered from the User and Group Administration module.

From this menu, you can add, delete or edit a user. The Expert Options button is used to set defaults that will apply to newly created accounts, and the Set Filter button lets you choose what you want displayed - local users are the default, but you can also choose system users or customize the display.

To edit a user, click the Edit button and you can change any of the existing settings for that user. If you click Details, you can see and change such values as the user ID, home directory, shell and so on. Conversely, clicking on Password Settings allows you to set password expiration and other variables.

You can add, edit and delete groups in the same way as you do with users.

Working with Security Settings is possible by first choosing Security and Users in the left pane and Security Settings in the right pane. The four settings that appear on this menu are:

• Level 1 (Home Workstation) - This is the lowest level of security that you can apply and should not be used in a business setting.
• Level 2 (Networked Workstation) - This is a moderate level of security and should be considered the minimum setting for a business.
• Level 3 (Network Server) - A high level of security recommended for servers.
• Custom Settings - The default.

You can choose any of the predefined roles and choose Details to tweak any individual settings. Alternatively, you can stick with the default of Custom Settings, and then click Next to see all the available options. (Next is only available if Custom Settings is selected.) The first screen that appears allows you to set password settings, and the next screen shows boot settings.

Following boot settings, you configure login settings and then parameters to affect newly added users and groups. Last, miscellaneous settings allow you to configure the user who runs updatedb (either nobody or root) and the settings on file permissions. You can choose from three possible file permission settings:

• Easy - The majority of configuration files can be read by users.
• Secure - Only root can read system files such as /var/log/messages.
• Paranoid - Access rights are the most restrictive possible.

You can see the individual settings for each of these levels by going to /etc and looking at permissions.easy, permissions.secure, and permissions.paranoid. Around 850 lines are in each file.

The Misc Option
When you choose Misc in the opening left frame of the YaST2 window, the following choices appear on the right:

• Autoinstallation
• Load Vendor Driver CD
• Post a Support Query
• View Start-up Log
• View System Log

These choices truly are a potpourri of selections that don’t comfortably fit anywhere else. One of the most useful options is to view the system log. When chosen, this automatically displays the contents of /var/log/messages and jumps to the end of the file to show the most current information.

Though messages is the default file shown, the drop-down box at the top left allows you to choose almost any log file and view its contents.

Less Work
YaST is a great tool in Novell’s versions of Linux which makes administrative tasks much easier through its text or graphical interface. You can configure settings for virtually everything, from software, hardware and networking to security and users; you can even make your own custom modules to add to the interface. Master it. Enjoy.

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