Tuesday, July 6, 2010

RHCE Study Guide

RHCE Study Guide for RHEL5 v1.1

Look at the latest objectives for the exam.

Remember the commands required.

If you don't understand a section, take that as a

clue that you need further study.

Practice, practice, practice!

Boot Single

boot into single user mode

at grub screen, "a", "space", "1", enter

Network Configuration

system-config-network

Files

/etc/sysconfig/network-scripts/ifcfg-eth0

/etc/sysconfig/network

Hostname Resolution

/etc/resolv.conf

/etc/hosts

X Window System

/etc/X11/xinit/xinitrc.d

/etc/X11/xorg.conf

/etc/inittab

system-config-display

/tmp and /home have enough space

Ctrl-Alt-F1 to F8

Ctrl-Alt-Backspace

Hard Disk Commands

fdisk /dev/hda

partprobe

mdadm -C /dev/md0 -l 5 -n 3 /dev/hda6

/dev/hda7 /dev/hda8

mke2fs -j /dev/md0

e2label /dev/hda2 /data

mount -t ext3 /dev/hda7 /data7

Configure Printing

system-config-printer

/etc/cups/cupsd.conf

lpadmin

lpstat, lpq

reject disable

accept /usr/bin/enable

Cron and at Jobs

copy script to /etc/cron.daily, /etc.cron.monthly

Modify /etc/crontab: crontab -e

List cron jobs: crontab -l

Add an at job: at [-f file] TIME

View at queue: atq

Remove at jog: atrm job

Install NIS or LDAP

Install ypbind, portmap

system-config-authentication

check: Enable NIS Support, or Enable LDAP

Support

click: Configure NIS..., or Configure LDAP...

configure firewall, if required

Test NIS or LDAP

ypwhich

nisdomainname -y

genent services

getent passwd smith

rpcinfo -p

NIS or LDAP Files

/etc/yp.conf

/etc/sysconfig/network

/etc/pam.d/system-auth

/etc/nsswitch.conf

Configure autofs

/etc/auto.master

/home/guests /etc/auto.guests

--

timeout=60

/etc/auto.guests

*

-rw,soft,intr

server1:/home/guests/&

service autofs restart

chkconfig portmap on

chkconfig autofs on

Manage Users, and Groups

groupadd -g 1000 groupname

useradd username

usermod -G groupname username

(-G for primary group)

Manage Quotas

quotacheck -cuf /home

quotaon /home

edquota username

quota username

repquota /home

Filesystem Permissions

mkdir -p /depts/finance

chgrp sales /depts/finance

chmod 770 /depts/*

chmod g+s /depts/*

chown sam /depts/managers

ls -l /depts/

Install and Update rpms

rpm -ivh filenamex.i386.rpm

rpm -Uvh filenamex.i386.rpm

Verify an RPM:

rpm --import /usr/share/rhn/RPM-GPG-KEY

rpm -K /tmp/rpmversion.i386.rpm

Install from yum Repository

/etc/yum.conf

/etc/yum.repos.d/

System Bootloader

/boot/grub/grub.conf

# root (hd0,0)

# kernel /vmlinuz-version ro

root=/dev/vg00/lv00 crashkernel=128M@16M

# initrd /initrd-version.img

Implement Software RAID

partprobe

mdadm -C /dev/md0 -l 5 -n 3 /dev/hda6

/dev/hda7 /dev/hda8

mke2fs -j /dev/md0

/etc/fstab

mdadm --detail /dev/md0

fail, recover, add:

mdadm /dev/md0 -a /dev/sda1

Set Kernel Run-time Parameters

vi /etc/sysctl.conf

xxx.xx.xxx=1

sysctl -p

sysctl -a | grep xxx

Diagnose and Correct Boot Failures

/etc/rc.d/rc.sysinit

/etc/rc.d/rc adn /etc/rc.d/rc?.d

/etc/rc.d/rc.local

/boot/grub/grub.conf

filesystem

/etc/fstab

fsck /dev/hda

Create a Logical Volume

First create physical volume, then volume

group, then logical volume PV -> VG -> LV

pvcreate /dev/hda6 /dev/hda7 /dev/hda8

vgcreate vg0 /dev/hda6 /dev/hda7

lvcreate -L 500M -n data0 vg0

ext2online /dev/vg0/data0

SELinux

getenforce

setenforce 1

check context with ls -Z

chcon -R --reference /var/www/html

/var/www/html/wwwnew

Configure HTTP

install httpd

modify /etc/httpd/conf/httpd.conf file

service httpd restart

chkconfig httpd on

service httpd configtest

Configure Samba Share

Install samba

vi /etc/samba/smb.conf

configure firewall

NFS

Modify /etc/exports

start nfs & portmap

verify config, & check mounts

exportfs -v

showmount -e localhost

rpcinfo -p localhost

service nfs reload

Automount

mkdir /net

vi /etc/auto.master

start services -- portmap, autofs

FTP

install vsftpd

create incoming directory

mkdir -p /var/ftp/incoming

vi /etc/vsftpd/vsftpd.conf

start vsftpd

service vsftpd start

Web proxy

Install squid, and start the service

vi /etc/squid

service squid reload

Configure browser to test

SMTP

Install sendmail, sendmail-cf, sendmail-doc

modify /etc/mail/sendmail.mc

m4 sendmail.mc > sendmail.cf (or make)

service sendmail restart

IMAP, IMAPS, and POP3

install dovecot

vi /etc/dovcot.conf

protocols = xxx

service dovecot restart

chkconfig dovecot on

SSH

/etc/ssh/

~/.ssh/

DNS

Install bind, bind-utils, and caching-nameserver

vi /etc/named.conf

To verify:

named-checkconf

named-checkzone example.com

example.com.zone

Check /etc/resolv.conf on client machines

NTP

/etc/ntp.conf

ntpstat

service ntpd restart

Firewall

/etc/sysconfig/iptables

iptables -L

iptables -F

service iptables save

service iptables restart

chkconfig iptables on

PAM

/lib/security/

/etc/pam.d/

Configure Service

Install RPM

rpm -ivh servicename.rpm

Modify Configuration and Firewall

Start Service

service servicename restart

Set Service to Start on Reboot

chkconfig servicename on