Chapter 3. System Configuration

Table of Contents
System Configuration With Linuxconf
System Configuration with the Control Panel

After installing your Red Hat Linux system, it's easy to think that the decisions you made during the installation are engraved in granite, never to be changed again. Nothing could be further from the truth!

One of the main strengths of Linux is that the operating system can be configured to do just about anything. Here at Red Hat, we try to make system configuration as easy and accessible as possible. To that end, we've worked hard on two fronts:

By developing system configuration tools in-house;
By working with outside developers of world-class system configuration tools.

Anyone familiar with Red Hat Linux over the years has probably seen what we call our "control panel" system configuration tools. These tools have been developed by Red Hat to make system configuration easier. And while these tools do make life easier for the Red Hat Linux user, we began a search for a system configuration tool with even more flexibility and power.

Our search ended with the inclusion of Linuxconf into Red Hat Linux 5.1 in June 1998.

One of Linuxconfs greatest strengths is the incredible range of configuration options under its control.

But what about the control panel tools? They're still there. While Linuxconf at present can do nearly everything the control panel tools can, there are two areas in which the control panel still holds the upper hand:

Printer configuration
Kernel daemon control

But now, let's take a look at Linuxconf…

System Configuration With Linuxconf

Linuxconf is a utility that allows you to configure and control various aspects of your system, and is capable of handling a wide range of programs and tasks. Fully documenting Linuxconf could be a separate book in its own right and certainly more than we can cover in this chapter. So we'll focus on those areas that address common tasks such as adding new users and getting connected to a network.

More information on Linuxconf, including its status, most recent release, and more can be found at the Linuxconf Project homepage:

http://www.solucorp.qc.ca/linuxconf/

This website includes fairly extensive information on Linuxconf including description, rationale, history, list of contacts and a lot of other information in addition to the software itself. It is maintained by Linuxconf's creator, Jacques Gelinas, so it's the best source of Linuxconf information on the Internet.

Notation

Accurately describing the location of specific screens within Linuxconf is easy, but lengthy given Linuxconf's hierarchical nature. If the structure was a family tree, most of the data entry screens are in the fourth generation. To describe the path to the screen where you would add new users to your system, we could write this out as:

"Select the Config option from the main screen, then the users accounts option off of that; on the users accounts screen that appears, select the normal option and then select the user accounts option."

Rather lengthy and not immediately accessible. Given the structural similarity to a family tree, we could write it as:

"main window beget Users accounts tab, beget Normal tab…"

But that's an awful lot of begets. Instead, we'll use the following format:

Config => Users accounts => Normal => User accounts

It's more concise and clear. It assumes as its base the Linuxconf entry screen. The other advantage to this approach is that it's not interface specific, so regardless of which interface you're using, you know exactly where the information is.

Running Linuxconf

To run Linuxconf you must have root access. If you are logged in as something other than root, there is an easy way to handle this situation. Use the su command to become root.

In case you aren't familiar with it yet, type su at the shell prompt and press Enter. The password you're asked to provide is the root account's.

Now, type linuxconf at the shell prompt to begin the program. Linuxconf has the following user interfaces:

Command line -- Linuxconf's command-line mode is handy for manipulating your system's configuration in scripts.
Character-Cell -- Using the same user interface style as the Red Hat Linux installation program, the character-cell interface makes it easy to navigate your way through Linuxconf, even if you aren't running X.
X Window-Based -- Linuxconf can take advantage of X, and give you an easy-to-use "point and click" tree menu interface (see the section called Tree Menu Interface for more information).
Web-Based -- A Web-based interface makes remote system administration a breeze; it can also be displayed with the character cell browser called Lynx.

Linuxconf will normally start in either character-cell or X mode, depending on the DISPLAY environment variable. The first time you run Linuxconf, an introductory message will be shown; although it is only displayed once, accessing help from the main screen will give you the same basic information.

Linuxconf has context-specific help available. For information on any specific aspect of Linuxconf, please select Help from the screen you'd like help with. Note that not all help screens are complete at this time; as help screens are updated, they will be included in subsequent versions of Linuxconf.

Tree Menu Interface

Linuxconf comes complete with a tree menu interface.

Figure 3-1. Linuxconf Entry Screen

Finding the appropriate panel should be simple and fast. You can collapse and expand sections by clicking on the menu item icons. Click the icon once to activate it for that particular sub-menu. A single click will then collapse it; another single click will expand it again.

Selected entries will appear as tabs in the right-hand panel and will remain there until closed. This will greatly reduce the clutter of windows on your desktop that Linuxconf has typically caused. If you end up with more tabs open than you like, just select Cancel on the bottom of each tab to close it without making any changes, or Accept to implement them.

Please Note: If you've grown fond of your previous X Window System interface, it's still available. To return to it:

Start Linuxconf by typing linuxconf at the shell prompt
Open Control => Control files and systems => Linuxconf modules
De-select the This module is active check box for the treemenu module.
Click Accept
Click Quit
Restart Linuxconf

Enabling Web-Based Linuxconf Access

For security reasons, Web-based access to Linuxconf is disabled by default. Before attempting to access Linuxconf with a Web browser, you'll need to enable access. Here's how to do it from the text-mode interface:

Start Linuxconf by typing linuxconf at the shell prompt
Open Config => Networking => Misc => Linuxconf network access
In the Linuxconf html access control dialog box, enter the hostname of any computers that should be allowed access to Linuxconf. This would also include your own system, if you wish to use the Web-based interface locally. Web accesses related to Linuxconf may be logged to your system's htmlaccess.log file by selecting the check box shown.
Select the Accept button and press Space. Then select the Quit buttons on each dialog box to back out of the menu hierarchy. When you come to a dialog box labeled >Status of the system, press Enter to take the default action, which is to apply the changes you've made.

At this point, Web-based access has been enabled. To test it out, go to one of the systems that you added to the access control list. Then, launch your Web browser, and enter the following URL:

http://<host>:98/

(Replacing <host> with your system's hostname, of course.) You should see the main Linuxconf page. Note that you will need to enter your system's root password to gain access beyond the first page.

Adding a User Account -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt
Open Config => Users accounts => Normal => User accounts
Select Add
Enter the account's login and full names
Enter information in other fields only as necessary
Select Accept
Enter the initial password for the account
Reenter the initial password for the account in the Confirmation field
Select Accept

Adding a User Account -- General Overview

Adding a user is one of the most basic tasks you will encounter in administering your system. To add a user:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts This will open the Users accounts tab (see Figure 3-3).
If you have more than 15 accounts on the system, Linuxconf will provide you with a filter screen (see Figure 3-2). You can use this to select a smaller range of accounts than the full list. To get the full list, select Accept without changing any of the parameters. For detailed information on the various filters, select the Help button on the Filter control screen.
Select Add. This will open the User account creation tab (see Figure 3-4).

Figure 3-2. Filter Control Screen

The User account creation tab is where you enter all the information on the new account. There are a number of fields you should be aware of, some required, some optional.

Figure 3-3. Users Accounts Screen

Figure 3-4. User Account Creation

Required Fields:

Login name -- the name of the account. Usually all lowercase letters. First or last names, initials or some combination thereof are fairly common login names. For a user named John T. Smith, "smith," "john," "jts," or "jsmith" would be common user names. Of course "spike" or something else works just fine, too. You can also use numbers, so "jts2" would be fine if you had a second person with the same initials. There is no default for this field.

Optional Fields:

Full name -- this is the name of the user or the account. For an individual, it would be their name, "John T. Smith" for example. If the account represents a position rather than a person, the full name might be the title. So an account called "webmaster" might have a full name of "Red Hat Webmaster" or just "Webmaster." There is no default for this field.
group -- here you can specify the group associated with the account. The default is a group that's the same as the login name. So "jsmith" would have the group "jsmith."
Supplementary groups -- here is where you can specify any additional groups. We suggest that if you want to add a user to a group or groups, you do so here, rather than changing the group field. Group names should be separated by spaces. The default for this field is blank, meaning no supplementary groups.
Home directory -- specifies the home or login directory for the account. The default is /home/login, where login is replaced by the login name. A home directory is your starting point in the directory structure when you log in, or if in X, for each xterm window opened. This is also where account specific preference files are stored.
Command interpreter -- specifies the location of the command interpreter. Command interpreters are usually referred to as shells. The default is displayed in the drop down box.
User ID -- the number associated with each user account. This is automatically generated by the system when the account is created.

The User account creation screen has a number of fields; only the login name is required, though filling in the Full name field is strongly recommended. Once you have entered the login name and any other desired information select the Accept button at the bottom of the screen. If you decide against creating a new user, select Cancel instead.

Figure 3-5. Change Password Screen

When you click on Accept Linuxconf will prompt you to enter the password. There is also a field called Confirmation where you will need to type the password again. This is to prevent you from mistyping the password. Passwords must be at least 6 characters in length. They may contain numbers as well as a mix of lowercase and uppercase letters. Press the Accept button again when finished.

Modifying a User Account -- Quick Reference

Please Note: Although you can change the settings in any user account, it is usually a bad idea to change the settings in a pre-created account. It is best to change settings and explore options in an account that you have created yourself.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
Select the user account.
Modify entries as desired.
Select Accept.

Modifying a User Account -- General Overview

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts. This will open the Users accounts tab (see Figure 3-3).
If you have more than 15 accounts on the system, Linuxconf will provide you with a filter screen (see Figure 3-2). You can use this to select a smaller range of accounts than the full list. To get the full list, select Accept without changing any of the parameters. For detailed information on the various filters, select the Help button on the Filter control screen.
Select the account you wish to modify. This will open the User information tab.

Figure 3-6. User Information Screen

On the User information screen, the information can be changed as desired. To implement the changes select Accept. If you decide against making any changes select Cancel. This guarantees that no changes are made.

Changing a User's Password -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
Select the user account.
Select Passwd.
Enter the user's new password.
Reenter the user's new password in the Confirmation field.
Select Accept.

Changing a User's Password -- General Overview

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts. This will open the Users accounts tab (see Figure 3-3).
If you have more than 15 accounts on the system, Linuxconf will provide you with a filter screen (see Figure 3-2). You can use this to select a smaller range of accounts than the full list. To get the full list, select Accept without changing any of the parameters. For detailed information on the various filters, select the Help button on the Filter control screen.
Select the account whose password you wish to change. This will open the User information tab (see Figure 3-6).
Select Passwd from the options at the bottom of the screen.

Linuxconf will then prompt you to enter the new password. There is also a field called Confirmation where you will need to type the password again. This is to prevent you from mistyping the password. Passwords must be at least 6 characters in length. They may contain numbers as well as a mix of lowercase and uppercase letters. If you decide against changing the password, just hit Cancel. Once you have entered the new password select Accept.

Changing the root Password -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Change root password.
Enter the current root password.
Select Accept.
Enter the new root password.
Reenter the new root password in the Confirmation field.
Select Accept.

Changing the root Password -- General Overview

Changing the roots password isn't handled in the same manner as changing a user's password. Because of both the importance and security considerations surrounding root access, Linuxconf requires you to verify that you currently have access to the root account.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Change root password.

Figure 3-7. Root Password Verification Screen

Here, Linuxconf wants the current root password to verify access to the root account. Linuxconf does require root access to run, but once running there's nothing to keep anyone from sitting down at the computer if the person using Linuxconf steps out for a minute. The potential pitfalls are extensive! If the person who was originally using Linuxconf logs out of root, they won't be able to get back into it. A lack of validation would also give free reign over the computer to whoever had changed root's password.

Once you have entered root's current password, it will prompt you for a new password. There is also a field called Confirmation where you will need to type the password again (see Figure 3-5). This is to prevent you from mistyping the password. Passwords must be at least 6 characters in length. They may contain numbers as well as a mix of lowercase and uppercase letters. If you decide against changing the root password, just hit Cancel. Once you have entered the new password select Accept. The change takes place immediately and is effective not only for logging in as root, but also for becoming root using the su command.

Disabling a User Account -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
Select the account.
Deselect the account is enabled check box.
Select Accept.

Disabling a User Account -- General Overview

Why disable an account? Good question! There's no single answer, but we can provide some reasons why this option is available. The biggest reason is security. For example, you may have created a special account to be used by clients, co-workers, or friends to access specific files on your system. This account gets used from time to time, but should only be used when you know there's a need. Leaving an unused account around is a target for people who'd want to break into your system. Deleting it requires you to recreate it every time you want to use it. Disabling an account solves both problems by allowing you to simply select or de-select a check-box.

To disable an account:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
De-select the check-box that states that The account is enabled. Select the Accept button at the bottom of the window and you're all set.

The account is disabled and can be enabled later using a similar method.

Enabling a User Account

By default, all newly created user accounts are enabled. If you need to enable an account, you can use Linuxconf to do it.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
Select the account you want to enable.
Select the The account is enabled check-box and then select Accept at the bottom of the screen.

Deleting a User Account -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => User accounts.
Select the account you wish to delete.
On the User information screen select Del.
On the Deleting account… screen, choose the appropriate option for the account's data.
Select Accept.

Deleting a User Account -- General Overview

Please Note: While there are a couple options that let you retain files associated with an account, any information or files deleted are gone and effectively unrecoverable. Take care when using this option!

To delete an account:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => User accounts.
On the User accounts screen (see Figure 3-3) select the account you wish to delete.
At the bottom of the User information screen (see Figure 3-6) select Del to delete the account.

Linuxconf will then prompt you with a list of options.

Figure 3-8. Deleting Account Screen

The default option is to archive the account's data. The archive option has the following effects:

Removes the user from the user accounts list;
Takes everything contained in the user's home directory and archives it (using tar and gzip compression), storing the resulting file in a directory called oldaccounts. For an account named useraccount the file name would be similar to:
useraccount-1999-10-10-497.tar.gz
The date indicates when the account was deleted, and the number following it is the ID of the process that actually performed the deletion. The oldaccounts directory is created in the same place as all of your user directories, and is created automatically the first time you remove a user account using this option.
Files not contained in the user's home directory, but owned by that user remain. The file is owned by the deleted account's user ID (UID). If you create a new account and specifically assign it the UID of a deleted account, it will then become the owner of any remaining files.

Selecting Delete the account's data on the Deleting account <accountname> screen (see Figure 3-8) will:

Remove the user from the user accounts list;
Remove the user's home directory and all its contents.

Please Note: Files not contained in the user's home directory, but owned by that user will remain on the system. The file will still be owned by the deleted account's user ID (UID). If you create a new account and specifically assign it the UID of a deleted account, it will then become the owner of any such "orphaned" files.

Selecting Leave the account's data in place on the Deleting account <accountname> screen (see Figure 3-8) will:

Remove the user from the user accounts list;
Leave the user's home directory (with all its files) in place.

Please Note: Files and directories owned by the deleted account's user ID (UID) will remain on the system. If you create a new account and specifically assign it the UID of a deleted account, it will then become the owner of these "orphaned" files.

Groups

All users belong to one or more groups. Just as each file has a specific owner, each file belongs to a particular group as well. The group might be specific to the owner of the file, or may be a group shared by all users. The ability to read, write or execute a file can be assigned to a group; this is separate from the owner's rights. For example, the owner of a file will be able to write to a document, while other group members may only be able to read it.

Creating a Group -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definition.
Select Add.
Enter the Group name, and optionally alternate members.
Select Accept.

Creating a Group -- General Overview

To create a new group:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definition.

If you have more than 15 groups, you will be given the option to select the groups by providing a prefix.

Figure 3-9. Group Filter Screen

You may add a group directly from this screen, or move on to the User groups screen. To move on select Accept with or without a prefix, to add a new group, hit Add.

Figure 3-10. User Groups Screen

Select Add at the bottom of the User groups screen.

Figure 3-11. Group Specification Screen

Enter a group name. You may also wish to specify members of the group and can do so in the Alternate members field. The list of users should be space delimited, meaning that each username must have a space between it and the next one. When you're finished, select Accept and the group will be created.

Deleting a Group -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definitions.
Select the group you wish to delete.
Select Del.
Confirm deletion.

Deleting a Group -- General Overview

To delete a group:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definitions.

If you have more than 15 groups, you will be given a filter screen (see Figure 3-9) to narrow your choice of groups by specifying a prefix.

With or without a prefix select Accept at the bottom of the screen.
On the User groups screen (see Figure 3-10) select the group you wish to delete.
You'll be presented with the Group specification screen (see Figure 3-11).
Select Del to delete the group. Linuxconf will then prompt you to confirm the deletion. Choose yes to delete the group.

The group's files will still remain and their respective owners will still have sole control over them. The group name will be replaced with the deleted group's ID. The files may be assigned to a new group by using the chgrp command. More information on chgrp can be found by typing the command info chgrp or man chgrp at the shell prompt. If a new group is created and the deleted group's ID is specified then the new group will have access to the deleted group's files. Don't worry, Linuxconf doesn't recycle old group numbers any more than it does old user IDs, so it won't happen by accident.

Modifying Group Membership

There are two ways to modify the list of users that belong to a group. You can either update each user account itself, or you can update the group definitions. In general, the fastest way is to update each of the group definitions. If you're planning on changing more information for each user than just the group information, then updating each user account may prove easier.

Modifying Group Membership -- Quick Reference

Under Groups:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definitions.
Select the group to which you wish to add or remove users.
Add or remove new users to the Alternate members(opt) field; make sure all user names are separated with a space " " character.
Select Accept.

Modifying Group Membership -- Quick Reference

Under Users:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.
Select a user to which you wish to add or remove groups.
Adjust the Supplementary groups field accordingly; make sure all the group names are separated with a space " " character.
Select Accept.
Repeat steps 3 through 5 for each additional user to be added.

Modifying Group Membership -- General Overview

We'll start by detailing the group definitions method.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => Group definitions.

If you have more than 15 groups, you will be given a filter screen (see Figure 3-9) to narrow your choice of groups by specifying a prefix.

With or without a prefix, select Accept at the bottom of the screen.
Select the group you wish to modify. This will open the Group specification screen (see Figure 3-11).
Add or remove each user from the Alternate members field. Make sure that all of the user names are separated by a space " " character.
Once you've done this select Accept which can be found at the bottom of the screen.

This will automatically update each user account with the group showing up in the Supplementary groups field if added or absent if removed.

Adding and removing groups can also be done by modifying each individual user account.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Users accounts => Normal => User accounts.

If you have more than 15 accounts on the system, Linuxconf will provide you with a filter screen (see Figure 3-2).

On the User accounts screen (see Figure 3-3), select a user that you wish to update. You will be presented with the User information screen (see Figure 3-6).
Add or remove the desired groups from the Supplementary groups field. Each group should be separated by a space " " character.
Once you've made all the changes you'd like, select Accept at the bottom of the screen.

This will automatically update the group definitions. Repeat the process for each user.

CD-ROMs, Diskettes, Hard Drives and Filesystems -- the Inside Track

A filesystem is composed of files and directories, all starting from a single root directory. The root directory may contain any number of files and other directories, with each directory in turn following suit. The average filesystem often looks like an inverted tree with the directories as branches and the files as leaves. Filesystems reside on mass storage devices such as diskette drives, hard drives, and CD-ROMs.

For example, a diskette drive on DOS and Windows machines is typically referenced by A:\. This describes both the device (A:), and the root directory on that device (\). The primary hard drive on the same systems is typically referred to as the "C" drive because the device specification for the first hard drive is C:. To specify the root directory on the C drive, you would use C:\.

Under this arrangement, there are two filesystems -- the one on A:, and the one on C:. In order to specify any file on a DOS/Windows filesystem, you must either explicitly specify the device on which the file resides, or it must be on the system's default drive (which is where DOS' infamous C prompt comes from -- that's the default drive in a system with a single hard drive).

Under Linux, it is possible to link the filesystems on several mass storage devices together into a single, larger, filesystem. This is done by placing one device's filesystem "under" a directory on another device's filesystem. So while the root directory of a diskette drive on a DOS machine may be referred to as A:\, the same drive on a Linux system may be accessible as /mnt/floppy.

The process of merging filesystems in this way is known as mounting. When a device is mounted, it is then accessible to the system's users. The directory "under" which a mounted device's filesystem becomes accessible is known as the mount point. In the previous paragraph's example, /mnt/floppy was the diskette drive's mount point. Note that there are no restrictions (other than common conventions) as to the naming of mount points. We could have just as easily mounted the floppy to /long/path/to/the/floppy/drive.

One thing to keep in mind is that all of a device's files and directories are relative to its mount point. Consider the following example:

A Linux System:
- / --- system root directory
- /foo --- mount point for the CD-ROM
A CD-ROM:
- / --- CD-ROM's root directory
- /images --- a directory of images on the CD-ROM
- /images/old --- a directory of old images

So, if the above describes the individual filesystems, and you mount the CD-ROM at /foo, the new operating system directory structure would be:

A Linux System (with the CD-ROM mounted):
- / --- system root directory
- /foo --- CD-ROM root directory
- /foo/images --- a directory of images on the CD-ROM
- /foo/images/old --- a directory of old images

To mount a filesystem make sure to be logged in as root, or become root using the su command. For the latter, type su at the shell prompt and then enter the root password. Once you are root, type mount followed by the device and then the mount point. For example, to mount the first diskette drive on /mnt/floppy, you would type the command mount /dev/fd0 /mnt/floppy.

At installation, Red Hat Linux will create /etc/fstab. This file contains information on devices and associated mount points. The advantage to this file is that it allows you to shorten your mount commands [1] . Using the information in /etc/fstab, you can type mount and then either the mount point or the device. The mount command will look for the rest of the information in /etc/fstab. It's possible to modify this file by hand, or by using Linuxconf. To use Linuxconf, please see the section called Reviewing Your Current Filesystem -- Quick Reference immediately following.

Reviewing Your Current Filesystem -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => File systems => Access local drive or to look at your network environment: Open Config => File systems => Access nfs volume.

Reviewing Your Current Filesystem -- General Overview

We'll start by looking at your current directory structure.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => File systems => Access local drive.

Figure 3-12. Local Volume Screen

The fields are:

Source -- The physical hardware; hd indicates an IDE hard drive, fd indicates a diskette drive, and cdrom typically indicates a CD-ROM drive. If your system has a SCSI drive, you will see an sd instead. More than one drive of a type are listed by letters, so hda represents the first IDE drive, while hdb would be the second. In some cases, you'll see numbers following these letters; on hard drives, the numbers represent the partitions on that drive, while for diskette drives, this number refers to the actual unit.
Mount point -- This is where in the system the drive is to be mapped when mounted.
FsType -- This is where the type of filesystem is indicated. A standard Linux partition uses the ext2 filesystem type. A filesystem type of vfat indicates a DOS filesystem with long filename support, while a fat filesystem type is for DOS filesystems supporting traditional 8.3 filenames. The iso9660 filesystem type indicates a CD-ROM drive, as seen in Figure 3-12.
Please Note: Red Hat Linux 6.1 can access FAT32 filesystems using the vfat filesystem type.
Size -- Size indicates the size of the filesystem in megabytes (M). For removable media devices such as diskette and CD-ROM drives the stated size is listed as zero.
Partition type -- A description of the filesystem used on that partition.

Filesystems from other machines on a network may also be available. These can range from single small directories to entire volumes. No information on Size or Partition type is available for these partitions, either. Additional information on these filesystems (should you have any available) will be contained under:

Config => File systems => Access nfs volume

Figure 3-13. NFS Volume Screen

The screen is similar to the Local volume screen (see Figure 3-12), with some notable differences in the information provided for each entry:

Source -- This will be the name of the machine serving the filesystem, followed by the remote directory. For example: foo:/var/spool/mail where foo is the machine serving the directory, and /var/spool/mail is the directory being served.
FsType -- This will always be "nfs."

Adding NFS Mounts -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => File systems => Access nfs volume.
Select Add.
Enter the host name where the filesystem resides.
Enter the path to the remote filesystem in the Volume field. For example, /var/spool/mail.
Specify the mount point on your system. For example, /mnt/foo.
Select Accept.

Adding NFS Mounts -- General Overview

NFS stands for Network FileSystem. It is a way for computers to share sections of their local filesystem across a network. These sections may be as small as a single directory, or include thousands of files in a vast hierarchy of directories. For example, many companies will have a single mail server with individuals' mail files served as an NFS mount to each users' local systems.

To add an NFS mount:

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => File systems => Access nfs volume.
On the NFS volume screen (see Figure 3-13), select Add.

Figure 3-14. Volume Specification Screen

The three fields on the Base tab are what you'll need to concern yourself with.

Server -- The host name of the machine the desired filesystem resides on. For example, foo.bar.com.
Volume -- The filesystem you wish to add. For example, /var/spool/mail.
Mount point -- Where in your system you want the remote file system accessible from. For example, /mnt/mail.

This is all you need to get the mount created. Linuxconf will update your /etc/fstab file accordingly. If you are aware of additional requirements, please read the help file on the Volume specification screen and see the mount man page for more information.

Once you have entered the information, select Accept.

Getting Connected with Linuxconf (Network Configuration)

The first thing to determine when getting hooked up is whether you're connecting to a local area network, such as a group of computers in an office, or a wide area network, such as the Internet. Before continuing, it's important to know what hardware you have and how you intend to connect. If you're going to dial into another computer, then make sure your modem is installed and that the cables are arranged properly. If you're using a network card, make sure it is installed properly and that the cables are correctly connected. Regardless of what network configuration you specify, if every phone line or cable is not in place, you'll never get connected. We'll start with modem connections and then move on to using network cards.

Adding Modem/PPP/SLIP connections -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Networking => PPP/SLIP/PLIP.
Select Add.
Select the type of connection.
Enter the phone number, login name and password.
Select Use PAP authentication only if necessary (only available for PPP accounts).
Select Accept.

Adding Modem/PPP/SLIP connections -- General Overview

Red Hat Linux 6.1 uses the utility called RP3, or the RH PPP Dialer, a graphical tool which helps users configure and monitor network accounts -- particularly PPP accounts. (To read more about RP3, see the related chapter in the Official Red Hat Linux Getting Started Guide.) However, you can still depend on Linuxconf to set up network configuration.

There are several pieces of information you will need to get from your ISP (Internet Service Provider) or systems administrator before getting your PPP or SLIP account working. In the case of some providers, you may have to sort through directions on how to set up a PPP connection on a Linux system. Some ISPs are ill-equipped to handle individuals using Linux. Don't worry, you can still get connected; you just need some additional information from your ISP.

The following is what you need for a connection with Red Hat Linux. The ISP representatives may respond that you don't need this information, or may suggest that you need more than this. Red Hat has streamlined the information needed using intelligent defaults and tools such as Linuxconf to simplify this process for you. Unless they have a document specifically for Red Hat Linux, just request the information below and go from there. Specifically, you'll need:

the IP address for a domain nameserver (DNS);
the telephone number to dial;
your login and password;
an IP address for your machine if the network you are connecting to isn't going to provide you with a dynamic one;
whether or not your ISP uses an authentication method such as PAP, CHAP or MS-CHAP. If so, you will need a "secret" to enable authentication. The secret will be a word or sequence of characters. CHAP and MS-CHAP are not currently supported using Linuxconf, and are rarely used.

Additional information which may be helpful, but isn't necessary includes a secondary nameserver address, and a search domain. Once you have all this information, you're ready to get connected.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Networking => PPP/SLIP/PLIP.
Select Add.

Figure 3-15. PPP/SLIP/PLIP Configurations Screen

Initially there won't be any configurations specified. When you select Add you will be given a choice between PPP, SLIP and PLIP.

Figure 3-16. Type of Interface Screen

PPP is the most commonly used interface and is the default. To set up a PPP connection select PPP and hit Accept.

Figure 3-17. PPP Interface Screen

You'll see the following fields:

Phone number - number used to access to remote system;
Modem port - indicates where your modem is. Should already be set.
Use PAP authentication (check box) - check if you know that the system you are dialing into requires this;
Login name - your login name for the PPP account;
Password - your password for the PPP account.

Notice that the title bar is PPP interface ppp0. ppp0 is the first PPP interface, ppp1 would be the second and so on. It's important to keep track of which interface you're using if you have more than one. SLIP connections use sl instead of ppp for their interface prefix. With the exception of a PAP authentication option, the entry screens for adding a PPP or a SLIP account are identical.

Figure 3-18. SLIP Interface Screen

Enter the complete phone number for the remote machine, and make sure to include any numbers required to access outside lines.

For example, if you need to dial "9" and then the number, and the computer you're connecting to has a telephone number of "555-0111," then you'd enter "95550111."

The next information you're asked for is the modem port. This is a drop down box of available ports. If you're using a dual-boot Linux/Windows system and you know the COM port your modem is on, the following map may be of use:

Map to Windows COM ports are as follows:

ttyS0 -- COM1: under MS-DOS;
ttyS1 -- COM2: under MS-DOS;
ttyS2 -- COM3: under MS-DOS;
ttyS3 -- COM4: under MS-DOS.

The login name is the one for the PPP account. The password you enter will be shown in plain text, so be careful who you have around when you enter it! If you will be using PAP authentication, check the box; when you've entered the other required information, select the Customize button at the bottom of the screen. All the other information is provided on the various tabs and can be set within the Customize screen, but it's easier to find the information all in one place on the primary screen.

Figure 3-19. PPP Interface Customization Screen

Select the PAP tab and enter your username and then the secret the ISP has provided you in the Secret field. The other defaults should be sufficient, but if you need to, you can edit the initial settings using the Customize option.

Modifying a PPP or SLIP Configuration -- Quick Reference

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Networking => PPP/SLIP/PLIP.
Select the configuration to modify.
Change the desired settings; most are on the Communications tab.
Select Accept.

Modifying a PPP or SLIP Configuration -- General Overview

You can edit an existing configuration as well as delete it by selecting it from the list on the PPP/SLIP/PLIP configurations screen.

Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Networking => PPP/SLIP/PLIP.
You will then be presented with the PPP/SLIP/PLIP configurations screen (see Figure 3-15). Select the configuration you would like to modify or delete.

This will open the appropriate interface screen for your configuration. If you wish to delete the configuration, the handy Del button is there at the bottom of the screen. The Modem port is on the Hardware tab and is a drop down menu. If you want to change the other settings you entered when you originally created the configuration, select the Communication tab. The first Send field contains your login, and the next Send field contains your password. The Expect fields correspond to the login: and password: prompts, which explains the ogin: and ord: entries.

Please Note: The ogin: and ord: entries may not be the same for your system. Different ISP/PPP servers may use different text and should be changed to fit the needs of whatever server type you are logging in to. Instead, you may see such prompts as User ID and authentification.

Figure 3-20. SLIP Interface Customization Screen

Once you have made your changes, you can test to see if your configuration is working. Select Connect from the bottom of the screen. This will attempt to connect you to the remote system using the information you've entered. Once you've finished configuring and testing your setup, we recommend using the usernet utility to control your dial-up networking connection on a daily basis. See the usernet man page for more information.

Other Network Connections -- Quick Reference

Due to the number of possible choices and sub-choices, no quick reference is available for this section.

Other Network Connections -- General Overview

Setting up a network connection over ethernet requires an entirely different type of setup. Network connections to token ring or arcnet networks follow a similar procedure, but will not be discussed here.

First you will need to have an Ethernet card installed.
Start Linuxconf by typing linuxconf at the shell prompt.
Open Config => Networking => Client tasks => Basic host information. The Host name tab will request a host name, which should be specified by default unless you did not setup your networking during the installation process. If it is not already specified, please take the time now to configure it. It should be specified at localhost.localdomain. Skip this tab. Select the tab for Adaptor 1.

Figure 3-21. Adaptor 1

The first item on this screen is a check box to indicate whether this adaptor is enabled or not. It should be checked if this is the one you intend to use. Below that is a choice of Config modes. Manual means that you will be providing all the information and entering it yourself. DHCP and bootp retrieve their information from a remote server of the corresponding kind. If you're not sure what option to choose, talk to your network administrator.

DHCP and bootp Required fields:

Net device - The type of network card you are using; for example, eth0 would be the appropriate entry to use the first Ethernet card.
Kernel module - The correct module based on your network card; for further information see the list below.

For DHCP and bootp configurations you only need to specify the Net device and the Kernel module. For the Net device, you will choose from a list where the eth prefix represents ethernet cards, the arc specifies an arcnet card and the tr specifies token ring cards. A complete list of network cards and their respective modules can be found in Appendix B. For the most up-to-date list, please see our website at:

http://www.redhat.com

The netmask information will be set by default, although depending on what kind of network you are setting up, or becoming a part of, you may need to specify this. If you are connecting to an ISP, ask them for the information. Most likely it will be 255.255.255.0 (the default).

Required fields for Manual Configuration:

Primary name + domain -- the primary name is the name of your computer, while the domain is how your network is specified. For example, foo.bar.com; foo is the primary name and bar.com is the domain.
IP address -- this is the address of the machine and will follow the pattern of x.x .x.x. For example, 192.168.0.13.
Net device -- type of network card you are using; eth0 would be the appropriate entry to use the first ethernet card.
Kernel module -- the correct module based on your network card.

Information on net devices and kernel modules is described above. The appropriate primary name + domain and IP address will depend on whether you are adding the computer to an existing network or creating a new network. For connecting to an existing network, contact your network administrator for the information. Getting a network connected to the Internet is beyond the scope of this book, and we recommend the following starting point:

TCP/IP Network Administration, 2nd Edition, by Craig Hunt (O'Reilly and Associates).

If you're setting up a private network that won't ever be connected to the Internet, then you can choose any primary name + domain name you would like and have several choices for IP addresses (See Table 3-1).

Table 3-1. Addresses available and Examples

Addresses available	Examples
10.0.0.0 - 10.255.255.255	10.5.12.14
172.16.0.0 - 172.31.255.255	172.16.9.1, 172.28.2.5
192.168.0.0 - 192.168.255.25	192.168.0.13

The three sets of numbers above correspond to class a, b, and c networks respectively. The classes are used to describe the number of IP addresses available as well as the range of numbers used to described each. The numbers above have been set aside for private networks.

Please Note: You should not use these IP addresses if you connect to the Internet since 192.168.0.* and 192.168.255.* are not reliably considered private. If you want your network to be connected to the Internet, or think you might want to at some point in the future, do yourself a favor and get yourself non-private addresses now.

Nameserver Specification

A nameserver and default domain are also needed to establish a network connection. The nameserver is used to translate host names such as private.network.com to their corresponding IP address such as 192.168.7.3.

The default domain tells the computer where to look if a fully qualified hostname isn't specified. Fully qualified means that the full address is given, so foo.redhat.com is the fully qualified hostname, while the hostname is simply foo. If you specified your default domain as redhat.com, then you could use just the hostname to connect successfully. For example ftp foo would be sufficient if your search domain is redhat.com, while ftp foo.redhat.com would be required if it wasn't.

To specify the nameserver, open Config => Networking => Name server specification (DNS).

Figure 3-22. Resolver Configuration Screen

Nameservers are ranked according to the order in which they are accessed, so it's not unusual to see nameservers referred to as primary, secondary, tertiary and so on down the list if more than one is specified. Each of these must be an IP address and not a name. The computer has no way to resolve the name until it connects to a nameserver. Screamingly obvious when stated, but occasionally overlooked when people are simply asked to supply an address for a computer.

In addition to a default domain, you can also specify search domains. Search domains work differently; they progress from one to six in a similar manner to the nameserver. However, they all take precedence over the default domain! Keep this in mind when specifying search domains. Search domains are not commonly used.

The one item not yet covered is the check box for DNS usage. If you are running a small private network with no Internet connection, then using /etc/hosts files and keeping them all synchronized will work. As you add more and more machines, the complexity increases until it is easier to have a single machine run a DNS than to continue to sync /etc/hosts files.

There is another reason for not using DNS, and that is if your network is going to use NIS instead. Note that NIS can be used in conjunction with DNS. So to sum it all up, unless you know why using /etc/hosts or NIS would be best for your situation, DNS is probably going to be your best choice.

You can add, modify, or delete entries from the /etc/hosts file using Linuxconf. Open Config => Networking => Misc => Information about other hosts.

Figure 3-23. /etc/hosts Screen

To modify or delete an entry select it. To delete the entry, select Del at the bottom of the host/network definition screen.

Figure 3-24. Host/Network Definition Screen

To modify it, change the information as necessary. To add a new entry, select Add at the bottom of the /etc/hosts screen. This will also open the host/network definition screen.

Required Fields:

Primary name + domain -- the primary name is the name of the computer, while the domain is how the network it is attached to is specified. For example, given foo.bar.com, foo is the primary name and bar.com is the domain.
IP number -- also referred to as IP address; this is the address of the machine and will follow the pattern of x.x. x.x. For example, 192.168.0.13

Optional Fields:

Alias -- A shorthand for the fully qualified domain name. This is often the same as the primary name. So, for example, if the fully qualified domain name is foo.bar.com, you could select foo as the alias.
Comment -- a comment on the machine. For example, "The remote nameserver."

You will need to specify both the primary name + domain and the IP number. The other fields are optional. Once finished, select Accept.

Date and Time

To get to the date & time control panel:

Start Linuxconf by typing linuxconf at the shell prompt.
Enter root's password when prompted (if you're not already root).
Open Control => Date & Time.

Figure 3-25. Workstation Date & Time

The zone field is a pull-down list that is long and extensive. It is often designated by a large region and then a city or zone within it. Examples include Europe/Vienna and US/Eastern. There is a check box to Store date in CMOS in GMT format. Hours are specified from 0 (midnight) to 23 (11 PM). Months are specified by number as well. For the year, please specify all four digits. All other fields should be self-explanatory.

Notes