RED HAT CERTIFIED ENGINEER (RHCE) Study Guide

 

Table of Content Pre-Install Installation and troubleshooting System Configuration X Window System Linux Shells and Commands/Utilities Networking System Administration and Security Pre-Install Determine your Linux system's role in your network: WWW, FTP, NEWS, ISP, development workstation, thin client, enterprise server, application server, database server, etc. Collect hardware information: check out Red Hat 5.x HCL. Be familiar with the model and parameter of your hardware devices: keyboard, monitor (horizontal/vertical frequencies), mouse type (serial, PS/2, or bus mouse), protocol (Microsoft, Logitech, MouseMan, etc.), and number of buttons; printer, hard drive (IDE, EIDE, SCSI, Cylinder/head/sector geometry), sound card, video card, PC-Card (PCMCIA) etc. If you have IDE drives, you should check your computer's BIOS to see if you are accessing them in LBA mode. Collect network information: hostname, domain name, IP address, netmask, default gateway, primary and secondary name server, NFS server (optional), FTP server (optional). Be familiar with what packages that Red Hat comes with, so you can choose these during installation. Read the Linux hardware HOWTO (in Red Hat CD:\DOC\HOWTO) to clarify the hardware compatibility issue. Review IRQ settings and plan the IRQ layout. This table lists the standard IRQ layouts: Interrupt Line Device Comments 0 Timer   1 Keyboard   2 Cascade to IRQ9 On some systems, IRQ2 is the gateway to IRQs 9~15; avoid it if possible 3 COM2 Can also be COM4, but only one of the two 4 COM1 Can also be COM3, but only one of the two 5 XT hard disk controller, LPT2 Hard disk interface used only on XTs, or alternatively for LPT2 on the unusual machine with LPT2. This is free on most modern PCs, and is the "catch-all" IRQ for bus mice, sound cards, LAN boards, etc. 6 Floppy disk controller   7 LPT1   8 Clock   9 Possible cascade to IRQ2 May not be available 10   Generally available 11   Generally available 12 Motherboard InPort If your PC/laptop has a built-in mouse port, it probably sits here 13 Math Coprocessor This interrupt is required even if your CPU has a numeric coprocessor built in 14 Hard Disk   15 Unused Generally available   Hardware requirement for Red Hat 5.x installation: Hardware Device Minimum Suggest Comments Processor i386 SX without X i386 DX with X P166 MMX It's hard to find a processor older than a P166 in today's market. Hard Drive 60 MB 1 GB 600 MB for a complete installation Memory 4 MB 8 MB without X 16 MB with X   Create installation boot disk and supplemental diskette using rawrite program - location on CD is: \dosutils\rawrite.exe If Linux is to coexist with other OSs, create available hard drive space using fips utility (a program similar to Partition Magic). Location on CD: \dosutils\fips.exe Linux's primary file system is EXT2, and SWAP (for SWAP files). Linux supports plug and play. Installation and troubleshooting Use F3 key to go to expert mode - disables most of the auto probing and auto detection. Use F4 key, and both boot and supplemental disks to repair a damaged system. Use F6 key to pass some options to the kernel at the boot time. Example: boot: linux mem=128M will instruct the kernel to use 128MB system RAM. Red Hat 5.x Linux Kernel file name is vmlinuz. It's on the Boot disk and is less than 500 KB. initrd.img file is first loaded by system To install on the machine without CD-ROM: copy \RedHat\ directory tree from CD-ROM over Network to the hard drive before install. If IDE CD-ROM is not being detected, restart the installation process, key in instruction to kernel: boot: linux hdX=cdrom (X=a if CD-ROM is in ide0 master; X=b if CD-ROM is in ide0 slave; X=c if CD-ROM is in ide1 master; X=d if CD-ROM is in ide1 slave. Where ide0=primary channel and ide1=secondary channel). Partition disk using Disk Druid during installation. Know what is the Mount Point, Device, Requested, Actual, Type, and how to specify the particular parameter for them. Know Driver summary, especially what Geom [C/H/S] means. (Cylinders, Heads, Sectors). / and swap are default partitions to specify when using Disk Druid. Partition disk using fdisk during installation. Be familiar with following commands and their usages: Command Usage m display help menu p list current partition table t change system partition ID n add new partition d delete current partition l list known partition types q quit without saving changes w write changes and quit

• Linux partitions - It's recommended to create multiple partitions for Linux instead of using a single partition.

• Create ext2 (Second Extended filesystem) Linux filesystem partition using the mke2fs (make filesystem) command.
  Syntax:
  mke2fs -c <partition> <size>
  Example:
  mke2fs -c /dev/hda3 162344
  (162344 is the size in blocks.)
• Other than the ext2 file system, Xia file system, Extended filesystem, and Minix filesystem are available for Linux. To create those filesystems, use mkxfs (for Xia), mkfs (for Minix), and mkefs (for extended file system).
• Enable swap space for installation using mkswap command.
  Syntax:
  mkswap -c <partition> <size>.
  Example:
  mkswap -c /dev/hda1 13565
• Most PC BIOSs can't handle more than 1024 cylinders on a disk drive. You can't create DOS or Linux partitions or filesystems that go beyond the 1023rd cylinder ( SCO allows the user to do anything beyond the 1024 limit). Red Hat Linux can use partitions beyond the 1024 limit, but it can't boot from them.
• Before the end of installation, you will be prompted to create a Linux boot disk - a disk that is different from the one created by using rawrite. The bootable disk enables users to access the system at anytime, especially if the normal boot process fails. This disk is an emergency boot disk.
• (Create the boot disk after system installation.)
• Configure a modem during installation. /dev/ttys0 equivalent to COM1, /dev/ttys1 equivalent to COM2.
• Configure a mouse during installation. If the mouse is a serial mouse, choose the port. /dev/S0 corresponds to COM1, /dev/S1 corresponds to COM2, and so on. Don't select the same port as used by a modem.
• Set the boot device. If Linux will coexist with other OSs (such as DOS, NT), don't install LILO (Linux Loader) and overwrite the hard drive's MBR (master boot disk).
• Specify system boot up from boot floppy disk or from LILO.
• Choose the LILO installation to boot your system in different ways. Install bootloader to MBR vs. First sector of boot partition.
• Configure LILO by modifying the /etc/lilo.conf file.
• Use the pkgtool utility to install new software, remove existing software, or view installed files in a package.
• The following services should be turned on for a system to be fully bootable: atd, crond, inet, kerneld, keytable, network, and syslog.
• Install printers during installation. Specify printer queue (lp by default) and spool directory.
• Use the X Windows utility - printtool to add, edit, or delete printer after installation.
• Floppy disk problems - errors such as read error, file not found and tar: read error are disk medium related problems that usually occur on the floppy disk. If so, replace the floppy disk.
• Hard disk and disk controller related problems - while Linux boots, it runs a partition check. If it does not display correct partition information, check the cables inside you PC and make sure a power connector is connected to each disk drive. Also check the partition table (using fdisk for example).
• For device conflict problems - collect information on IRQ (Interrupt) and DMA (Direct Memory Address). Check for conflicting problems. Use the DOS MSD utility or Norton utility.
• Default options entered to the LILO boot command will be passed to the Linux kernel every time it boots.
• Review your computer's BIOS settings. If your computer accesses a hard drive in LBA mode, check Use linear mode.
• Loadlin can load Linux from MS-DOS; it requires a copy of the Linux kernel (and an initial ram disk, if you have a SCSI adapter) to be available on an MS-DOS partition. The only way to accomplish this is to boot your Red Hat Linux system using some other method (e.g., from LILO on a diskette) and then copy the kernel to an MS-DOS partition.
• When installing Linux to coexist with Microsoft Windows NT use the bootpart utility.
• Choosing an installation class (for Red Hat 5.2 only): Workstation (automatically erase all Linux partitions from your computer's hard drives); Server (automatically erase all partitions from your computer's hard drives); Custom (gives you complete control over partitioning-related issues. If you have installed Red Hat Linux in the past, the custom-class installation is most similar to past installations.)
• Know the differences among CDROM, FTP, NFS, SAMBA, and Hard Disk installation.
• Checking the installation log file.
• View boot time information such as console install screens, virtual consoles, dmesg. Use page up/page down at the console.
• Understand the standard boot process.
• Verify the installation status: login as root and view dmesg.
• Generate the text file and automate the installation using kickstart mode.
• Install Linux in RAID configuration.
• Troubleshoot hardware conflict problems during Linux installation.
• Configure Linux installation on laptop with PCMCIA card and APM (Automatic Power Management) system.
• Understand the kernel daemon, etc/conf.modules and module parameters. Understand /llib/modules/... directory structure and contents.

System Configuration

• Checking file system type using /etc/fstab file, knowing its layout and meaning.
• Knowing basic user environment (etc/skel/) and home directories.
• Using rpm to 1) validating a package signature; 2) add and remove Linux components; 3) add updates, 4) verify packages (install or not); 5) check what package a file is in.
• Creating and using custom RPMs. 1) install source rpms; 2) verify /usr/src/redhat directory structure; 3) change compile time options for a source RPM; 4) rebuild custom source and binary rpms; 5) build an rpm from a tar archive.
• Adding, deleting and modifying users.
• Configure keyboard using kbconfig utilities.
• Mounting hard disks, floppy disks, and removable media using mount command.
• Configuring sound card using sndconfig utility.
• Knowing virtual consoles, daemons, netsysv, chkconfig utilities.
• Setting up and managing disk quotas:

1. Installing quota RPM
2. Modifying /etc/rc.d/rc.sysinit file
3. Modifying etc/fstab
4. Creating quota.user file for each partition
5. Using edquota to set up per user disk quotas
6. Creating default quota settings
7. Generating quota reports
8. Configuring quotas on nfs filesystems
9. Understanding monolithic vs. modular kernel concepts
• Updating linux kernel to newer version, kernel rpm's and tar file. Understanding kernel source tree and documentation.
• Configuring kernel scripts, compiling and installing a custom kernel or kernel modules.
• Updating LILO.
• Using mkinitrd and mkbootdisk utilities.
• Understanding kernel configuration options

1.        The standard Red Hat kernel configuration

2.        Code maturity level options

3.        Loadable module support options

4.        General set up options

5.        Floppy, IDE and other block device options

6.        Non IDE/SCSI CDROM support options

7.        Networking and network device options

8.        SCSI support options and low level drivers

9.        ISDN options

10.     File system options

11.     Character device options (serial and parallel ports, mice, QIC tapes, APM)

12.     Sound system support options

13.     Kernel profiling support

• Configuring system-wide shell configuration for Bourne and bash shells - /etc/bashrc, /etc/profile, /etc/profile.d - see Linux Shell section.
• Understanding the cron system - the system crontab and components, the user crontabs.

X Windows System

• Know how to check X Server supported hardware.
• Know how to check the X11 packages installation status by using the rpm and grep command. Example: rpm -qa | grep ^X
• Know how to install X Windows packages using rpm command. Example: rpm -ivh Xconfig*
• Know how to detect the video card chipset, amount of memory and RAMDAC chipset using SuperProbe utility.
• Know how to configure X Windows using the Xconfiguator program and XF86setup. Select the correct chipset and RAMDAC.
• Know how to configure a custom monitor by modifying the /etc/X11/XF86Config file.
• Know how to start X Windows using startx command.
• Know how to configure the system to start automatically in X Windows by modifying /etc/inittab file. Understand run levels and default run level and modifying the system startup script /etc/rc.d/rc.sysinit
• Know how to change video setting by modifying start.out file.
• Know how to exit from X Server using Ctrl-Alt-Bkspace
• Know how to troubleshoot the filesystem problem that causes a blank screen,  using fsck command.
• Know how to troubleshoot mouse related problems using the mouseconfig program.
• Know how to troubleshoot mouse related problems by modifying the /etc/sysconfig/mouse file.
• Know how to troubleshoot the gpm problem that causes mouse malfunction, how to stop the gpm program by running /etc/rc.d/init.d/gpm stop
• Know how to toggle gpm off using ntsysv command.
• Know this place to get Linux documentation: /usr/doc/HOWTO.
• Know the window manager configuration file locations (see below)
• Know how to install and configure the fvwm virtual window manager by modify the configuration file system.fvwmrc in the /etc/X11/fvwm directory.
• Know how to install and configure the fvwm2 Window manager by modifying the /etc/X11/fvwm2/system.fvwm2rc file and its symbolic link in /usr/X11R6/lib/X11/fvwm2.
• Know how to install and configure twm (Tab window manager) by modifying the configuration file system.twmrc in the /etc/X11/twm directory.
• Know how to install and configure mwm (motif window manager) by editing the .mwmrc file in the home directory. Get the source file from /usr/lib/X11/system.mwmrc.
• Know how to install and configure lwm (LessTif mwm window manager) by modifying the .mwmrc resource file in the home directory, and the Mwm file under the LessTif directory.
• Know how to install and configure CDE (the Common Desktop Environment). Know how CDE differs from other windows manager (X Display manager - xdm.)
• Know how to install and configure KDE (the K Desktop Environment) using rpm.
• Know about other X11 Window managers - Enlightenment, mlvwm, wm2
• Know how to change terminal settings of xterm, nxterm, and rxvt terminal. Select proper font settings using Ctrl-RightClick and the xfontsel command.
• Know how to use the X11 command line options (X Toolkit) to set geometry settings, foreground, background color, mouse and cursor modes, etc.

Linux Shells and Commands / Utilities Determine which shell the user has been assigned - look at the contents of /etc/passwd file. Linux Shell Comparison Table Shell Name Ash Bourne Bash (Bourne Again) Korn C-shell T-shell Zsh Author Kenneth Almquist   Brian Fox/Chet Ramey Eric Gisin   William Joy (plus 47 others) Paul Falstad Binary ash sh bash ksh csh tcsh zsh Built-in command 24   48 42   53 84 Command line options 10   12 20   18 50 Default Prompt   $   $ % %   Home Startup File   $HOME/.profile $HOME/.bashrc $HOME/Profile $HOME/<WBR.CSHRC< font> $HOME/.tcshrc or .chsrc   Note   default Linux shell   Korn shell is a commercial Unix shell. In Linux, pdksh shell is named ksh.     one of the largest Linux shells Understand what is an environment variable and where the configuration text file is located on your shell (example, for bash shell, is in /etc/profile). Specify the list of different environment variables by using printenv command. Understand #PATH variable. Know how to make temporary and permanent change of the #PATH variable. (Add the directory to your $PATH variable for the current login. Make a permanent change by adding the path to the profile file - say, .bash_profile in home directory.) Know what an alias is, and how to customize shells using an alias. Know how to run the program in the background. Example: rxvt & Know how to use pipe to redirect output of a program to a file, and redirect the content of the file to another program. Know how to build your own shell commands using chmod command. Assign shell variables to represent command line arguments to a shell command. Basic Linux Commands and Utilities Be familiar with the commands and utilities in this table. Check the man page for detailed usage, such as switch, pipe, etc.   Command Usage Note man get help the Linux manual sections, man1 to man9, are in /usr/man directory. cd move to a different directory know what .. and ~ can do as parameters to the CD command. pwd print working directory   find search directories for matching files -print switch; -xdev switch whereis find files from files directories   locate locate files from locate's database - locatedb locatedb is in /var/lib directory updatedb update locatedb database   whatis get command summaries   makewhatis build the whatis database (db of command summaries) makewhatis is in /usr/sbin directory apropos search for whatis database to get the program you want man -K option does the same thing ls list files and directories know the -m, -x, -F, -a, -l, -R, -d switches. Know how to use wildcards * and . dir, vdir list directories   tree list graphic directory know the -d option cat list, create, and combine files know the -n, -l, *, >, >> options and pipes. Know Ctrl-D to close file. more read files   less read files (allows scrolling, have more options than the more command) use zless command to compress files head, tail read the beginning and the end of files know the -q option touch create files know how to create a file and redirect output to a new file (use with Ls for example.) rm delete files know the -r, -f, -i  options and wildcards mkdir create directories know how to create multiple directories and create sub directories under existing directories rmdir removing directories -p option mv rename files   cp copy files   ln create hard and symbolic links -s option mc visual shell that display files   grep, egrep, fgrep, zgrep search inside files (zgrep can search compressed files) be very familiar with grep command tar create archives -c, -w, -t, -f, -v, -x options and combination cpio copy files in and out of tar or cpio archives   gzip, gunzip compress and uncompress files be familiar with files that have a .Z, .z,  .gz, -gz, -z, _z extension compress compress files   ps process status command   kill terminate a process   Ctrl-z put a running program into background in bash shell   fg bring back a program from background return a specific program using job number or job name. Example: fg %x (x=job number, or job name) pine a Linux mail program in KDE, use k-mail job get a list of suspended programs   sc a Linux spreadsheet program   mount, umount mount or unmount a file system

Linux Networking 

• Know central control files under /etc/sysconfig directory, /network-scripts subdirectory, the parameters and scripts in the files.
• Know how to configure the clock, mouse, static routes, keyboard, network and PCMCIA parameters by modifying files under /etc/sysconfig directory.
• Know how to configure the network interface using script files in /etc/sysconfig. ifup-type and ifdown-type are files that setup or deregister the interface. Types are lo (loopback), eth (Ethernet), sl (SLIP), ppp (PPP). Configuration is performed using the GUI program - netcfg.
• Know TCP/IP concepts: IPv4, IP octac, IP classes, subnet mask, default gateway, ICMP, FTP, ARP, router, sub-networking, default route, and CIDR (Classless InterDomain Routing), NNTP, etc.
• Know how to troubleshoot TCP/IP problems using utilities such as ping, netstat -rn, arp, traceroute, etc.
• Know how to configure IP parameters, enable the network interface, and check configuration of an existing network interface using ifconfig utility.
• Know how to use telnet and rlogin to connect Linux terminal from Windows machine.
• Know how to use Netscape and configure Netscape HTTP.
• Know basic Apache configuration for a simple web server.
• Know how to configure ftpd for anonymous ftp server.
• Learn about time synchronization
• Know how to configure PPP client using netcfg utility.
• Know how to configure an internal or external modem to connect to an ISP using PPP.
• Know how to configure SMB to act as a client and server for file and print services
• Know how to configure NFS as client and server.
• Know how to configure sendmail using SMTP, POP, and IMAP as a work station and how to modify the aliases file and sendmail.cf files.
• Understand how to turn on and turn off anti-spam.
• Know how to configure the Linux server to act as a boot and NFS host for Linux clients. Know how to start and stop NFS services.
• Understand Bootp and DHCP configuration, etc/exports, mounting and exporting file system via NFS.
• Be able to troubleshoot file locking issues.
• Know how to configure Linux and NT connectivity using Samba, and IPX (mars_nwe).
• Know how to configure network printing services, and add/remove local and remote printers.
• Understand etc/printcap file, etc/host file, lpc, lpq, and lprm.
• Know how to configure innd (leafnode service).
• Know how to use xntp and rdate to configure time services.
• Know how to configure Squid proxy server and web cache.

System Administration and Security

• Know how to maintain and preserve the consistency of common configuration files (password, group, hosts, services) using NIS (formally yellow pages - yp). Know RedHat's NIS components. Understand how to modify the etc/nsswitch.conf file.
• Know the basics of host security. Understand how to modify tcp_wrappers, etc/hosts.allow and etc/hosts.deny.
• Understand PAM (Pluggable Authentication Modules) and modifying files in the etc/pam.d/ directory.
• Know IP aliasing and virtual hosts.
• Understand firewall policies - elementgs ipfwadm
• Understand NAT (Network Address Translation), IP masquerading and IP forwarding.
• Know how to configure routing and static routes and the etc/hosts file.
• Understand the interaction of PC CMOS clock time and Linux system time.
• Know how to set up and verify system logging: syslog and klog; /etc/syslog.conf; remote logging; monitoring logs using swatch; managing logs using log rotate.
• Understand emergency boot procedures.
• Understand system log entries.
• Understand how to tailor etc/syslog.conf.
• Understanding Sgid redhat scheme and cops.
• Know how to use tmpwatch.
• Know how to use syslog for debugging and tracking problems.
• Know how to obtain encryption packages in rpm format. Consider:

1.       Import and export restrictions on encryption software

2.       The ftp.replay.com site

3.       Validating RPMs with pgp

• Know how to use linuxconf utility.