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Transcript of Intel Day1
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8/2/2019 Intel Day1
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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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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
Linux-Administration
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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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What Can You Do With Linux?
Linux Tablets
& Readers
Linux Cloud Services
Linux
Gaming
Linux Android for
Mobile Phones
Linux Arduino
Linux-Administration
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
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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
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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
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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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Linux-Administration 13
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!
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Classic Linux Distributions
Red Hat (Fedora)
Suse (Novell)
Debian
Knoppix
Slackware
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Popular Linux Distributions Ubuntu
Mint
CentOS
Puppy
http://distrowatch.com
Linux-Administration
Linux-Administration 16
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
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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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Red Hat Products
Linux-Administration 20
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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Linux-Administration 21
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
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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
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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!
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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
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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
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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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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
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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)
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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
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Network Configuration andFirewall Setup
ifconfig
redhat-config-network
Dynamic IP (DHCP)
Static IP
iptables
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Package Selection GUI: X, KDE, GNOME
Servers
Tools
Programming
Multimedia
Applications
Linux-Administration
Linux-Administration 40
System Initialization
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
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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:
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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
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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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System Shutdown and Reboot To reboot:
shutdown r to reboot
reboot or init 6
To halt:
shutdown s to halt
halt or init 0
Linux-Administration
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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
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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-Administration
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Summary
Linux History
Distributions
Linux and Unix
Installation
System Initialization
File system
Management
Booting Linux
Graphical Desktops
Command Line
Linux-Administration