Info

Maps all uids and gids to the anonymous user. Useful for NFS-exported public FTP directories, news spool directories, and so forth. The opposite option to all_squash, and is the default setting. Maps requests from remote root user to the anonymous uid gid. This is the default. Turns off root squashing. Allows the root user to access as the remote root. Set explicitly the uid and gid of the anonymous account used for all_squash and root_squash options. The defaults are nobody and nogroup. You...

Mounting NFS on Demand autofs

You can also mount NFS file systems using the automount service, autofs. This requires added configuration on the client's part. The autofs service will mount a file system only when you try to access it. A directory change operation (cd) to a specified directory will trigger the mount operation, mounting the remote file system at that time. The autofs service is configured using a master file to list map files, which in turn lists the file systems to be mounted. The etc auto.master file is the...

Sendmail nullclient Configuration

The nullclient version of Sendmail is a stripped down configuration that simply forwards all mail to the central server. It will not relay mail, nor will it deliver any mail locally. To configure a Sendmail client, you first need to comment out the DAEMON_OPTIONS line in the default Red Hat sendmail.mc file by placing a dnl word in front of it, as shown here. Removing this feature will allow you to receive messages over your local network. This entry is restricting Sendmail to the localhost...

B3ch

Figure 4-7 printconf printer queues For the options selection, you can specify printer features such as paper size and resolution. Red Hat also provides a Text Mode Setup Utility (setuptool) with which you can configure different devices and system settings, such as your keyboard, mouse, and time zone. The setuptool utility is useful if you have changed any of your devices-say, installed a new mouse, keyboard, or sound card. The setuptool utility is designed to be run from the command line...

Managing Users

Linux is designed to serve many users at the same time, as well as provide an interface between the users and the computer with its storage media, such as hard disks and tapes. Users have their own shells through which they interact with the operating system. As a system administrator, you can manage user logins on your system. You can add or remove users, as well as add and remove groups. You also have access to system initialization files you can use to configure all user shells. And you have...

Postrouting

Rules for redirecting or modifying outgoing packets, NAT table only You add and modify chain rules using the iptables commands. An iptables command consists of the keyword iptables, followed by an argument denoting the command to execute. For example, iptables -A is the command to add a new rule, whereas iptables -D is the command to delete a rule. The iptables commands are listed in Table 40-4. The following command simply lists the chains along with their rules currently defined for your...

The X Window System and XFree86

Linux and Unix systems use the same standard underlying graphics utility known as the X Window System, also known as X or X11. This means that, in most cases, an X-based program can run on any of the window managers and desktops. X-based software is often found at Linux or Unix FTP sites in directories labeled X11. You can download these packages and run them on any window manager running on your Linux system. Some may already be in the form of Linux binaries that you can download, install, and...

Cvs

Control Versions System, www.cvshome.org Automatic configuration for source code software compiling, www.gnu.org software autoconf Though there are Man pages for all the compilers and their tools, much more detailed information is available through the GNU info system. These are files located in the usr info directory that contain detailed descriptions and examples for various GNU tools. They are the equivalent of compact online manuals. There are info documents for the gcc compiler, the C and...

Ctrlz

Interrupt and stop the currently running program. The program remains stopped and waiting in the background for you to resume it. Cancel and end a job running in the background. List all background jobs. The jobs command is not available in the Bourne shell, unless it is using the jsh shell. List all currently running processes including background jobs. Execute commands at a specified time and date. The time can be entered with hours and minutes and qualified as A.M. or P.M. The redirection...

Security Configuration

Once you have installed your Linux system, you should carry out some basic security measures to protect your system from outside attacks. Systems connected to the Internet are open to attempts by outside users to gain unauthorized access. This usually takes the following forms Trying to break into the system Having broken in, changing or replacing system files with hacked or corrupt versions Attempting to intercept communications from remote users Changing or replacing messages sent to or from...

M L

List current masquerading connections (not valid for iptables). Set masquerading timeout values (not valid for iptables). Following the command, list the chain to which the rule applies, such as the input, output, or forward chain, or else a user-defined chain. Next, list different options that specify the actions you want taken. Options exist to specify the address a rule is to match on (-s, -d) and to specify the target the rule is to execute (-j). The -s option specifies the source address...

Receiving Centralized Mail

In a centralized setup, one of the hosts operates as a mail hub in which all mail is delivered to the mail server on that hub. A POP server could also be running on that hub that users could use to access their mail. MX records in the local network's DNS configuration would direct all mail meant for different hosts to the mail hub. Masquerading would establish a single domain name for all the users on your network, regardless of their hosts. Mail could be sent to just the mail hub and users...

Swat

Samba Web administration tool for configuring smb.conf with a Web browser enables you to use a Web page interface to create and maintain your Samba configuration file, smb.conf Samba provides four main services file and printer services, authentication and authorization, name resolution, and service announcement. The SMB daemon, smbd, provides the file and printer services, as well as authentication and authorization for those services. This means users on the network can share files and...

Introduction

The Red Hat Linux operating system has become one of the major Linux distributions, bringing to the PC all the power and flexibility of a Unix workstation as well as a complete set of Internet applications and a fully functional desktop interface. This book is designed not only to be a complete reference on Red Hat Linux, but also to provide clear and detailed explanations of Linux features. No prior knowledge of Unix is assumed Linux is an operating system anyone can use. This book identifies...

The Gnome Display Manager

The Gnome Display Manager (gdm) manages user login and GUI interface sessions. gdm can service several displays and generates a process for each. The main gdm process listens for XDMCP requests from remote displays and monitors the local display sessions. gdm displays a login window with boxes for entering a login name and password, and also displays a popup menu labeled Options with entries for sessions and shutdown submenus. The sessions menu displays different window managers and desktops...

Interface Basics

To start using Linux, you must know how to access your Linux system and, once you are on the system, how to execute commands and run applications. Accessing Linux involves more than just turning on your computer. Once Linux is running, you have to log into the system using a predetermined login name and password. Once on the system, you can start executing commands and running applications. You can then interact with your Linux system using either a command line interface or a graphical user...

M

Mode (includes permissions and file types) The following example verifies the proftpd package root turtle mypackages rpm -V proftpd To compare the installed files directly with the files in an RPM package file, you use the -Vp option, much like the -qp option. To check all packages, use the -Va option as shown here If you want to verify a package, but only know the name of a file in it, you can combine verify with the -f option. The following example verifies the RPM package containing the ftp...

File System Administration

Files reside on physical storage devices such as hard drives, CD-ROMs, or floppy disks. The files on each storage device are organized into a file system. The storage devices on your Linux system are treated as a collection of file systems that you can manage. When you want to add a new storage device, you will need to format it as a file system and then attach it to your Linux file structure. Hard drives can be divided into separate storage devices called partitions, each of which would have...

Kernel Administration

The kernel is the core of the operating system, performing core tasks like managing memory and disk access, as well as interfacing with the hardware that makes up your system. For example, the kernel makes possible such standard Linux features as multitasking, which allows several users to work on the same system. It also handles communications with devices like your CD-ROM or hard disk. Users send requests for access to these devices through the kernel, which then handles the lower-level task...

News Proxy and Search Servers

News servers provide Internet users with Usenet news services. They have their own TCP IP protocol, Network News Transfer Protocol (NNTP). In addition, servers exist that provide better access to Internet resources. Proxy servers speed Web access by maintaining current copies of commonly accessed Web pages, speeding access times by eliminating the need to access the original site constantly. They also perform security functions, protecting servers from unauthorized access. The search and...

The X Display Manager xdm

The X Display Manager (xdm) manages a collection of X displays either on the local system or remote servers. xdm's design is based on the X Consortium standard X Display Manager Control Protocol (XDMCP). The xdm program manages user logins, providing authentication and starting sessions. For character-based logins, a session is the lifetime of the user shell that is started up when the user logs in from the command line interface. For xdm and other display managers, the session is determined by...

Network Tools

You can use a variety of network tools to perform tasks such as obtaining information about other systems on your network, accessing other systems, and communicating directly with other users. Network information can be obtained using utilities such as ping, finger, and host. Talk, ICQ, and IRC clients enable you to communicate directly with other users on your network. telnet performs a remote login to an account you may have on another system connected on your network. Each has a...

Fmimh

Vf vil MEC MJBiyc ftfll HCMMm VIE-KMMvt VIT- i- amp E mr--rf j If your monitor does not appear on the list, then select a Generic entry usually Generic multisync . Xconfigurator will then supply horizontal and vertical frequency values in the labeled boxes at the bottom of the screen. Check that the correct horizontal and vertical frequencies are entered. If you enter values that are too high, you could overclock your monitor and possibly damage or destroy it. Do not...