Chapter 11. System Administration: Core Concepts


11. System Administration: Core Concepts

IN THIS CHAPTER

System Administrator and Superuser

391

Rescue Mode

397

SELinux

400

Red Hat Configuration Tools

415

rpcinfo: Displays Information About portmap

423

The xinetd Superserver

425

TCP Wrappers: Client/Server Security (hosts.allow and hosts.deny)

427

Setting Up a chroot Jail

428

DHCP: Configures Hosts

431

nsswitch.conf: Which Service to Look at First

435

PAM

438


The job of a system administrator is to keep one or more systems in a useful and convenient state for users. On a Linux system, the administrator and user may both be you, with you and the computer being separated by only a few feet. Or the system administrator may be halfway around the world, supporting a network of systems, with you being simply one of thousands of users. A system administrator can be one person who works part-time taking care of a system and perhaps is also a user of the system. Or the administrator can be several people, all working full-time to keep many systems running.

A well-maintained system

  • Runs quickly enough so users do not get too frustrated waiting for the system to respond or complete a task.

  • Has enough storage to accommodate users' reasonable needs.

  • Provides a working environment appropriate to each user's abilities and requirements.

  • Is secure from malicious and accidental acts altering its performance or compromising the security of the data it holds and exchanges with other systems.

  • Is backed up regularly, with recently backed-up files readily available to users.

  • Has recent copies of the software that users need to get their jobs done.

  • Is easier to administer than a poorly maintained system.

In addition, a system administrator should be available to help users with all types of system-related problemsfrom logging in to obtaining and installing software updates to tracking down and fixing obscure network issues.

Part V of this book breaks system administration into seven chapters:

  • Chapter 11 covers the core concepts of system administration, including Superuser, system operation, the Red Hat configuration tools and other useful utilities, general information about setting up and securing a server (including a section on DHCP), and PAM.

  • Chapter 12 covers files, directories, and filesystems from an administrator's point of view.

  • Chapter 13 covers installing software on the system, including how to use yum, pirut, Red Hat Network (RHN), up2date, BitTorrent, and wget.

  • Chapter 14 discusses how to set up local and remote printers that use the CUPS printing system.

  • Chapter 15 explains how to rebuild the Linux kernel.

  • Chapter 16 covers additional system administrator tasks and tools, including setting up users and groups, backing up files, scheduling tasks, printing system reports, and general problem solving.

  • Chapter 17 goes into detail about how to set up a LAN, including setting up and configuring the network hardware and configuring the software.

Because Linux is configurable and runs on a variety of platforms (Sun SPARC, DEC/Compaq Alpha, Intel x86, AMD, PowerPC, and more), this chapter cannot discuss every system configuration or every action you will have to take as a system administrator. Instead, this chapter seeks to familiarize you with the concepts you need to understand and the tools you need to use to maintain a Red Hat Enterprise Linux or Fedora Core system. Where it is not possible to go into depth about a subject, the chapter provides references to other sources.

This chapter assumes that you are familiar with the following terms:

block device (page 1021)

filesystem (page 1032)

root filesystem (page 1053)

daemon (page 1027)

fork (page 1032)

runlevel (page 1054)

device (page 1028)

kernel (page 1039)

signal (page 1055)

device filename (page 1029)

login shell (page 1041)

spawn (page 1056)

disk partition (page 1029)

mount (page 1043)

system console (page 1059)

environment (page 1031)

process (page 1049)

X server (page 1064)


Tip: If something does not work, see if the problem is caused by SELinux

If a server or other system software does not work properly, especially if it displays a permissions-related error message, the problem may lie with SELinux. To see if SELinux is the cause of the problem, put SELinux in permissive mode and run the software again. If the problem goes away, you need to modify the SELinux policy. Remember to turn SELinux back on. For more information refer to "Setting the Targeted Policy with system-config-securitylevel" on page 402.





A Practical Guide to Red Hat Linux
A Practical Guide to Red HatВ® LinuxВ®: Fedoraв„ў Core and Red Hat Enterprise Linux (3rd Edition)
ISBN: 0132280272
EAN: 2147483647
Year: 2006
Pages: 383

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net