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Linux Administration

Copyright 2012: All Rights Reserved. Day

Red Hat Linux

Administration & ProgrammingIntel, Portland, OR

Jan 16-19 2012

2

Content

Linux History

Distributions

Linux and Unix

Installation

System Initialization

File system

Management

Booting Linux

Graphical Desktops

Command Line

Linux-Administration

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3

Unit 1: History Linux Is Not UniX

Developed by Linus Torvalds

8/25/1991

Based on Minix, a Unix clone

Free to use, install & modify Based on GNU tools

Licensed under GNU GPL


4

What Could You Do With Linux?

VPN link to remote site

Linux

Web server

Linux

router

Linux mail server

Linux print server

for UNIX clients

Linux DHCP

server

Linux

FTP server

Linux

NFS file server

NIS server

DNS server

Linux

firewall

Linux

VPN gateway

Linux file and

print server for

Windows clientsTo the

Internet

Linux

DataBase

Linux

Application

serverLinux-Administration

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5

What Can You Do With Linux?

Linux Tablets

& Readers

Linux Cloud Services

Linux

Gaming

Linux Android for

Mobile Phones

Linux Arduino


Linux-Administration 6

Linux Operating System

Linux

kernel

GNU tools,

compiler,

libraries

X graphics :

KDE GNOME

Other:

Apache, Database,

Multimedia

Linux

operating

system

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The GNU System Free Software Foundation: FSF.ORG

Objectives were to create freely distributable

UNIX tools

Software should be free from patents & commercial

ownership

GNU provides many UNIX commands & useful

applications


The Linux Kernel Began as Linus Torvalds personal project to

Run a UNIX-like operating system on an i386 PC

Offered as FREE to use & modify (GPL)

Version 0.02 was made public on Oct 1991

www.Kernel.org

Linux was originally written forIntel processorsbut now supports over 30 processors!

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X11A powerful networked graphical environment Developed at MIT, freely distributable

X.org - complete implementation of X based on

the X11R7.6 standard

Servers typically do not require graphics

Some useful system administration tools are

graphical

X graphical tools can be run on a server anddisplayed remotely

MIT = Massachusetts Institute of Technology


Other Linux Applications UNIX software packages have been ported

Korn Shell, emacs, zip, chkconfig

Many server components are generic UNIX

software: Apache, sendmail, BIND, Samba

Free implementations of commercial applications

OpenSSH, OpenMotif, GNUPG

Internationalization

Multiple languages

Unicode support!

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Hardware Utilization Linux runs without problems on older

computers

Linux works well on high-performance

modern hardware

Linux can run on many embedded systems!

https://openwrt.org

http://arduino.org


Security Linux supports many security features

UNIX security to control access resources

Pluggable Authentication Modules (PAMs)

Kerberos

Firewall protection for the Internet

IPsec

Hardened shared libraries

Downloaded software can be verified for

authenticityIPsec = IP security

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Low Cost Linux & most Linux software are free Commercial software for Linux is low cost (or free)

Often no need to purchase new hardware

Software updates are also free (or low cost)

Support by distributors and other organizations

available at reasonable cost

Enterprise Linux provides the reliability and

support of commercial UNIX at a reasonable price FREE as in FREEDOM!

14

Classic Linux Distributions

Red Hat (Fedora)

Suse (Novell)

Debian

Knoppix

Slackware


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15

Popular Linux Distributions Ubuntu

Mint

CentOS

Puppy

http://distrowatch.com



Linux Distrubution

Linux

kernel

GNU tools,

compiler,

libraries

X graphics :

KDE GNOME

Other:

Apache, Database,

Multimedia

Linux

operating

system +

Installation tools,

configuration tools,

Support, Applications

Red

Hat

Debian

SUSE

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What Is a Linux Distribution?A Linux distribution is:

A preconfigured kernel

GNU utilities

X graphical environment (KDE, GNOME)

Other generic software components

Distributor-specific installation & configuration

Support


Red Hat

Worlds leading open source application platform

Started as a consumer distribution in NC

After 10 years it decided to focus on the enterprise

Red Hat Enterprise Linux (www.redhat.com/rhel)

18-24 month release cycle

Purchased with one year Red Hat Network / support contract

CLIENT or SERVER versions

Fedora (fedoraproject.org)

Updates every 6 months

Unsupported, community based

Red Hat

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Copyright 2012: All Rights Reserved. Day 1-


Red Hat Products


Red Hat Network

Provides software updates (up to 7 years)

Management & Monitoring Modules

Extended capabilities for large deployments

Provisioning Module

Bare-metal installation, configuration

management, & multi-state

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Red Hat Installation Installer

Multi-tasking Linux

Anaconda, a python script

Source

CD, DVD, USB drive

Network: FTP, NFS, HTTP

Kickstart file simplifies similar installs


Package Manager: RPM

Red Hat Package Manager has:

Compiled or Source Software

Documentation & program help

Installation / un-install scripts

Its classified by group or family

Disadvantage: dependencies

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Package Manager: YUM Newer Red Hat versions use: YUM

Solves Dependencies

Can have multiple repositories

One click Update of:

Operating System

Applications

Utilities


Running Commands

Commands have the following syntax:

command options arguments

Options modify a command's behavior

Single-letter options usually preceded by -

Can be passed as -a -b -c or -abc

Full-word options usually preceded by --

Example: --help

Arguments data needed by the command (filenames)

Multiple commands can be separated by ;

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Getting Help Two important commands: man & info

commandhelp

Others (x = command):

whatis x - short descriptions of command

which x displays command location

locate x finds a file

Program help (F1) Red Hat Documentation or web site!


Hands-on Lab 1a Exploring Linux

Boot from Fedora CD or DVD

Login as fedora

Select Applications, System Tools, Terminal or start

a terminal window by pressing CTRL-ALT-F2)

From command line type: w (or uptime; who)

to find who is logged in & server uptime

From command line type: dmesg | more

to read kernel log

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Hands-on Lab1b

From command line type: freeto find out about memory utilization

From command line type: df hto find out about free disk space on mounteddevices

From command line type: mountto find out about available mounted devices

From command line type: ps axto display running processes


Hands-on Lab1c From command line type: more /etc/inittab

to read operating system defaults

From command line type: more /etc/fstabto read file system defaults

Try the man command for any of the previouscommands, or even help to get more detail on the

previous commands! Try the GUI tool from Applications, System

Tools, System Monitor and look at the differenttabs.

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Linux Installation

29Linux-Administration

30

Linux Installation Steps

Source: CD/DVD/USB/LAN installation

Target: Supported Hardware

CPU, RAM

Hard drive, Array

Network & Video

Network Configuration

Software Selection


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HW: CPU & Memory Support Intel, AMD, MIPS, PowerPC, SPARC

Itanium, Alpha, UltraSPARC, IBM z90

SMP support: up to 64 CPUs

RAM: min 256MB up to 64GB


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Bus Support

System & Hot swappable

Plug & Play

USB

Firewire (IEE1394)

Older Buses: EIDE, SCSI, PCMCIA,ISA


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33

Laptops, Mobile

Tricky installations

Custom bus, Video and/or Sound

chipsets

Older laptops may be difficult to install

Boot from CD, floppy or network

URL: www.linux-laptop.net


34

Configuring RAID

RAID levels supported

Level 0: striping w/o parity

Level 1: disk mirroring

Level 5: striping with parity


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Configuring Flexible

Filesystems with LVM LVM allows easy partition grow or

resizing

ONLY available in RHEL in GUI mode

Physical/Logical Volume (PV, LV)

Physical/Logical Extent (PE, LE)

Volume Group (VG)


36

Red Hat Installer Features GUI or text modes

CD or network install; kickstart install

Modes:

Rescue, Desktop, Workstation, Laptop,Server, Custom, Upgrade options.

Runs Anaconda, a Python script Multi-tasking kernel


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Partitioning Hard Drives GUI or text tools available during install

Auto or Manual modes

/boot partition

Dual boot systems

Swap partition (2x RAM)

Create LVM or RAIDs


38

Network Configuration andFirewall Setup

ifconfig

redhat-config-network

Dynamic IP (DHCP)

Static IP

iptables


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39

Package Selection GUI: X, KDE, GNOME

Servers

Tools

Programming

Multimedia

Applications




BIOS Boot Kernel init services Login

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BIOS Initialization Power On Self Test recognizes hardware,

CPU, memory, bootable config from CMOS.

bootable devices:

CD ROM

Floppy

Hard Drive

Network USB devices


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The Boot Loader

Last step in BIOS

Loads first partition of bootable device

It can present a preset menu of choices

Under Linux:

LILO (Linux Loader) older, static GRUB more dynamic, reads ext2


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Kernel Initialization Kernel loads based on parameters passed

All logging goes to /var/log/dmesg

Detects hardware

Loads initrd (if necessary)

Mounts root

Loads /lib/2.6.x/modules

Passes control to /sbin/init


44

init Initialization

Init loads scripts from /etc/rc.d

init.rc is the master script

Based on parameter or /etc/inittab

default, it will execute scripts in rc.x

All boot scripts live in init.d, can be

configured via chkconfig

Last script is rc.local


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Run levels Depending on the server usage or

situation you may want to start at:

Text (Console) login

Graphical login

Maintenance mode

Default is controlled by /etc/inittab

id:3:initdefault:


46

Daemon Processes

Run unattended

Do not write to console

Write via logging facility, usually to

/var/log/messages

Can be started via service command

service sendmail start

service sendmail stop


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The rc.sysinit Script Controls the initial mounting of

filesystems, repairing if needed

rc.local allows local customization


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System V run levels

0 - Halt

1 - Single user mode

2 - Multiuser, without network

3 - Full multiuser mode

5 - X11 (graphical login) 6 - Reboot


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The rc.local Script Backdoor for customization of your

system

Red Hat uses it to build /etc/issue at

boot time

Can be used to configure additional

hardware or new scripts


50

Virtual Consoles

Linux starts with 6 default virtual

consoles

Alt-F1 to Alt-F6 (or CTRL )

Can have up to 63 consoles


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51

System Shutdown and Reboot To reboot:

shutdown r to reboot

reboot or init 6

To halt:

shutdown s to halt

halt or init 0



Controlling Services service servicename function

Function: start / stop / restart / status

kill PID

nice level process

GUI: System Tools,System Monitor

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Configuring Services chkconfig servicename function

Function add del list

Try: chkconfig list | sort

system-config-services

From GUI: Applications, System

Settings, Server Settings, Services


54

System Monitoring andProcess Control

uptime + ps = w

ps ax

kill signal PID

killall process

top


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Hands-on Lab 2

Exploring Linux

Boot from Red Hat CD or USB

From command line type:

dmesg | more to read kernel log

From command line type:

runlevel to find current run level

From command line type:less /etc/inittab to read system defaults


Linux Graphical Environments

X Window System

GNOME

KDE


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GUI Components X Server

X Client

X Tools

GUI Tools

Calendar

CalculatorFile Manager


X Server OverviewClient

application

Xlib

X server

Device drivers

Client

(window

manager)

Xlib

Client

application

Xlib

Toolkit

Network X11

protocol


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X Principles X is considered inappropriate on a server

GUI tools can be very useful and convenient

An X server manages a physical display

Controls who can use the display

Controls who can receive events from a display

Communicates using the X11 protocol

Implements device drivers for drawing and handling

mouse and keyboard events


Linux X Servers XFree86 implements X11R6

Comes with Slackware and other flavors of

Linux

Also available for other operating systems

XFree86 actually has a separate X server for

each display controller type

MetroX and AcceleratedX are other types ofcommercial X servers


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Virtual Displays and Desktops Screens containing a lot of windows become cluttered

Some window managers have a larger display area than

screen

Visible area pans when the cursor gets near the edges

Display area

Screen


Configuring X

Various tools are available for configuring X

xf86config comes with XFree86 but is difficult

to use

xf86cfg is available on some distributions

Red Hat uses redhat-config-xfree86


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Network Configuration


Network Device Recognition

All Standard devices are recognized bythe kernel at boot time

Odd or extra hardware can be turn on oroff by loading modules

Red Hat customized networking:

/etc/sysconfig/network /etc/sysconfig/network-scripts directory

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Network Interfaces lo or dummy 127.0.0.1

eth0, tr0 are aliases to real kernel

modules, defined in /etc/modules

Network devices can be configured

with: system-config-network


Address Resolution Protocol

ARP is used in the TCP/P network to

find other systems

We query a server for a hostname & we

get an IP address

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Enabling Network Interfaces To start: ifup device

To stop: ifdown device

To start network device & services:

service network start

To stop network device & services:

service network stop


Multiple NICs

Each card will have its own

configuration file

Can be enabled/disabled at boot time

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Binding Multiple IP Addresses Many ISPs use multiple IP to provide

many hosts or domains from 1 system

Its a kernel feature

ifconfig eth0 10.0.0.1

ifconfig eth0:1 10.0.1.1

ifconfig eth0:X 10.0.X.1


Interface Configuration Files

In the /etc/sysconfig/network-scripts

directory there are text files for each

device detected:

ifcfg-eth0 foreth0

ifcfg-lo forloopback (lo)

Which contain the IP or DHCP setting,netmask & if device should start at boot

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Configuration Utilities ifup, ifdown

system-config-network

ifconfig

arp

nslookup, dig

hostname netstat


DHCP/BOOTP

Dynamic Host Control Program is thenewer version of the Boot Protocol

A client requests from a server an IPaddress at boot time

If granted, the server provides a leasefor the IP address, the netmask, & canprovide name server & gateway info

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Network ScriptsAllowing User Control of Network

Interfaces

The ifup & ifdown interface scripts are

the only scripts that the user should use

to bring up & take down network

interfaces


System Default Route

The route command displays & configs route

information

Newer kernels set default route automatically

For troubleshooting:

route shows / configs the IP routing

static tables can be set to host or net default keyword specifies a route which will be

used if no other route matches

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IP Forwarding There are kernel variables you can alter to change

the way the kernel behaves while its running

To configure a Linux computer as a router between

networks, you may want to activate IP forwarding

with the following command:

# echo 1 >> /proc/sys/net/ipv4/ip_forward


Global Network Parameters

The interesting bits are in /proc/sys/net

Reverse Path Filtering

Generic ipv4 /proc/sys/net/ipv4/icmp_echo_ignore_all

/proc/sys/net/ipv4/ip_default_ttl

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Name Resolution Berkley Internet Name Domain (bind)

from www.isc.org

Server name: named uses

/etc/named.conf

4 modes: master, slave, caching-only,

forwarding-only


DNS Client Configuration

/etc/resolv.conf

nameserver 10.0.1.254

/etc/hosts.conf

order hosts, bind

/etc/nsswitch.conf

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DNS & Network Diagnostics arp

nslookup

dig

host

netstat nr

tcpdump or ethereal

80

Summary

Linux History

Distributions

Linux and Unix

Installation


File system

Management

Booting Linux

Graphical Desktops

Command Line


Download - Intel Day1

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