Advance linux presentation_0702011

LINUX TRAINING

Open Technology Centre,
National Informatics Centre,
DIT, MCIT, Govt of INDIA,
E-3-A, Rajaji Bhavan, Besant Nagar, Chennai-600090.

Open Technology Centre, Chennai 1

Operating Systems

• A program that acts as an intermediary between
a user of a computer and the computer
hardware.

• Operating systems provide an environment in
which a user can execute programs.

• A program that controls the execution of
application programs.
OPERATING
SYSTEM DESIGN


OPERATING SYSTEMS SERVICES

● File Mangement
● I/O Management
● Memory Management
● Device Management
● Resource Management
● CPU Management
● Hardware Management


Operating Systems Evolutions

MICROSOFT WINDOWS OS/2

OPERATING SYSTEMS
DOS
LINUX

OPERATING
SYSTEM DESIGN
SOLARIS
MAC


Operating Systems View

OPERATING
OPERATING DETAILED OPERATING LINUX OPERATING
SYSTEM DESIGN
SYSTEM DESIGN SYSTEM DESIGN SYSTEM DESIGN


LINUX vs Windows

Particular Linux Windows
Software Cost Free /Low Costly

Easy Easy Easier
More Reliable than
Reliability Windows Required further improvement

Sofware Tools Less Numbers but freely More but Cost
Hardware driver and user
Interfaces Few Many
More vulnerable to
Security Very few attacks viruses/attacks

Open Source Yes No

Support Less Compare to windows Better Support


LINUX ORIGIN

• Linux is a “free” Unix-type operating system originally
created by “Linus Torvalds” with the assistance of
developers around the world.

• August 25 1991 “Linus” conceives the idea of Linux and
announces the project.


INTRODUCTION TO LINUX

• Open Source.
• Modular Fashion.
• Strong Security.
• Structured File Systems.
• Multi-User, Multi-Tasking Operating System.


Why LINUX?

Linux, is a free, UNIX-like operating system.

Works on any kind of Hardwares ( PC/Workstations
/Embedded Systems/Mainframe).

Comes with complete development environment includes
compilers, toolkits, scripting Languages.

Linux provides rich Graphical User Interface (GUI) Support.

Strong Security Nature – iptables, file permissions,
ownership's.


LINUX FLAVOURS


Type of Distribution – Community Edition


Type of Distribution – Commerical Edition


LINUX INSTALLATION

• Multiple Operating
system
• Multiple Partitions
within an operating
system
• Different file system
types


LINUX BOOT SEQUENCES

System Startup BIOS

Master Boot Record
Stage 1 Boot Loader

Stage 2 Boot Loader LILO, GRUB

Kernel Linux

Init User - Space


LINUX BOOT SEQUENCES - Run Levels

● A runlevel is a software configuration of the system
that allows only a selected group of processes to exist.
● Init can run the system in one of six runlevels.
0 - halt
1 - Single user mode
2 - Multiuser, without NFS (The same
as 3, if you don't have networking)
3 - Full multiuser mode
4 - unused
5 - X11
6 - Reboot


LINUX APPLICATION PACKAGES
Server

• Database Server – PostgreSQL
• Web Server – Apache, Apache Tomcat
• Mail Server – Cyrus
• Proxy Server – Squid
• Firewall – iptables
• NTP Server – ntp
• DHCP Server - dhcp
• N/W information service - NIS
• N/W File System - NFS
• Windows File Share - Samba
• Remote Connection - openSSH Server


LINUX APPLICATION PACKAGES
Desktop

● Office Software – OpenOffice, koffice
● Graphics - Gimp/CAD Programmes (QCAD)
● Internet Browser – Mozilla, Konqueror
● Emulation / Virtual Terminal – SSH
● Development – C, C++, Perl , Python & gcc
● Editor – Emacs, Vi / Vim
● Sound & Video – VLC, Brasero Dics Burner
● Mail Client – Evolution
● Chat – Empathy


LINUX FILE STRUCTURE
• In the Linux operating system, all filesystems are
contained within one directory hierarchy.

• The root directory is the top level directory, and
all its subdirectories make up the directory
hierarchy.

• This differs to other operating systems such as
MS-Windows.

• All directories are grouped under the root entry
"/".


LINUX FILE STRUCTURE


LINUX FILE STRUCTURE...

root - The home directory for the root user

home - Contains the user's home directories

bin - Commands needed during bootup

sbin - Like bin but not for normal users.

proc - Is a virtual filesystem that exists in the
kernels imagination which is memory.



usr - Contains all commands, libraries, pages
and static files.

lib - Unchanging data files for programs and
subsystems.

local - The place for locally installed software
and other files.

mnt - Allows to mount the external partion.



boot - Files used by the bootstrap loader, LILO
Kernel images are often kept here.

var - Files in /var are dynamic and are constantly
being written to or changed.

etc - Configuration files specific to the machine.

dev - Contains device files for interfacing with
hardware. Either block or character devices.


LINUX CONFIGURATION FILES

/etc/crontab - Lists commands and times to run them
for the cron deamon.

/etc/exports - Exporting file systems using NFS service.

/etc/fstab - Lists ther file systems mounted at boot
time Automatically.

/etc/group - Contains basic group attributes for
system Groups.

/etc/hosts.conf - Specifies the hostnames are resolved.


LINUX CONFIGURATION FILES...

/etc/hosts - lists hosts for name lookup that are
locally Required.

/etc/inittab - Configuration file for init, controls
startup run Levels, determines scripts
to start with.

/etc/passwd - The users database contains
username, encrypted password, user
default shell.users home directory.

/etc/profile - Contains the files that are executed at
startup time.



/etc/shells - shells file contains a list of '' login
shells '' on the system.

/proc/devices - file displays the various character
and block devices currently configured.

/var/log/lastlog - Tells about the last login time on the
System.

/var/log - Contains system log files.


/etc/rc.d/rc0.d - Contains the file that are used to control at
run level 0.
run level 1.
run level 2.
run level 3.
run level 4.
run level 5.
run level 6.


LINUX KERNEL

Kernel - “ heart of the operating system ”

The kernel image isn't so much an executable
kernel, but a compressed kernel image.

A routine that does some minimal amount of
hardware setup and then decompresses the kernel
contained within the kernel image and places it
into high memory.


SHELLS IN LINUX
A shell is a program that provides the traditional,
text-only user interface for Linux and other Unix-
like operating systems. Its primary function is to
read commands that are typed into a console.

Types of shells:
* Bourne shell (sh) - /bin/sh
* C shell (csh) - /bin/csh
* TC shell (tcsh) - /bin/tcsh
* Korn shell (ksh) - /bin/ksh
* Bourne Again SHell (bash)- /bin/bash


Working in the File System

• Viewing the file system
• Creating files and Directories
• Removing files and Directories
• Linking Files
• Change Directory
• List of Files
• Copy or Move files and Directories
• Clear Shell Commands
• Kernel version
• Exit, Shutdown & Reboot


Viewing File system...(1)

tail - Output the last part of files, print the last part
(10 lines by default) of each FILE.

Example
1. tail /var/log/syslog
Display the last 10 lines of the file called syslog.

2. tail -f /var/log/syslog
-f - output appended data as the file grows.



less - lets an admin scroll through configuration
and error log files, displaying text files.

Ex: 1. less /html/index.html

more - Paginates the specified file so it can be
read line by line (using Enter key).Use b key to
move back and q to quit.

Ex: 2. more /home/html/index.html



cat is to read and redirect the output to another
file.

Ex: cat /etc/hosts
– Prints specified file to the screen.

Ex: cat file.a > file.b
- cat is redirected using the output
redirection operator.


Creating File and Directories (1)

touch - create a simple empty file
Ex : touch file-name
touch test.txt

vim - using vim editor create a file
Ex : vim test.txt
creates a empty txt file in the name of test


Creating Files and Directories (2)

mkdir - Create one or more directories.

Ex: 1. mkdir personal
Create a directory named personal

Ex: 2. mkdir -p work/junk/questions
Create intervening parent directories if they don't
exist


Removing Files and Directory (1)

rm – Allows the user to remove one or more files
and and directories.

Ex: (1) rm /home/index.html
– Delete the File index.html

(2) rm -rf /home/test/Desktop/testing
- Delete the file or directory force-fully

Note: -rf cause unrecoverable deletion, If file is a directory, remove
the entire directory and all its contents, including subdirectories.


Linking Files

ln – used to make link between existing files.

Ex: ln -s /home/otc/Desktop/test /mnt/


Change Directory

Change the current working directory to dirName.

Ex: cd /path/to/the/directory

cd personal – change the directory into personal.
cd .. - Back to the previous directory
cd - switch to the previous previous directory


ls - list

ls
List information about the FILEs (the current directory by
default). Sort entries alphabetically.

Ex : 1. ls - List the contents of a directory.

2. ls -ld - Check the Permissions of the directory.

3. ls -al - List the hidden contents of a directory.


cp - copy & mv - move

cp
copies files from one location to another within system

Ex: (1) cp /home/test/Desktop/test.txt /opt/test.txt.orgi

mv

Commands for moving files are fairly straightforward. To change
the location of a file, use the mv command.

Ex: (1) mv /home/test/Desktop/documents.odt /data1


alias
alias

Create an alias, aliases allow a string to be substituted for
a word when it is used as the first word of a simple
command.

SYNTAX:
alias [-p] [name[=value] ...]
unalias [-a] [name ... ]

Ex : 1. alias ls = 'ls -F'
- Now issuing the command 'ls' will actually run 'ls -F'


Kernel version

uname
This command is helpful when working on different
computers which may not be in synch at the OS level.
Also, you can print information about those systems.

Ex: 1. uname -a
- This will print to the screen the Linux Kernel in
use on your system.


Clear Shell Commands

clear

Clears your screen if this is possible. It looks in the environment for
the terminal type and then in the terminfo database to figure out
how to clear the screen.

Ex: (1) clear


Reboot, Poweroff, Shutdown
reboot/halt/poweroff/shutdown

halt or reboot is called when the system is not in
runlevel 0 or 6.

Ex: (1) reboot or init 6 – Reboot the system
(2) poweroff – poweroff the system
(3) shutdown -r 5
• - Shutdown the system in 5 minutes and
reboot.


Exit and Logout

exit
● The exit causes normal program terminate.

logout
● Exit a login shell.

● A login shell, is your topmost shell, and is started

when you log in.
● Terminate a login shell allow to logged out.


LINUX GUI

● Gnome
● KDE


LINUX GUI

Gnome – GNU Network Object Model Environment

The GNOME is a desktop environment, a graphical
user interface that runs on top of a computer
operating system.

The GNOME desktop environment, an intuitive and
attractive desktop for users, and the GNOME
development platform, an extensive framework for
building applications that integrate into the rest of
the desktop.


LINUX GUI - GNOME


LINUX GUI

KDE

KDE is the easier Linux GUI for users with Windows
background.

It is best known for its Plasma Desktop, a desktop
environment provided as the default working
environment on many Linux distributions, such as
openSUSE, Mandriva Linux and Kubuntu.


LINUX GUI - KDE


ADVANTAGE OF LINUX GUI

● It provides user friendly to the novice user.
● It invokes multi-GUI environment in Remote.
● GUI allows to take full advantages of multi-
tasking.
● We can do all the CLI operations in GUI mode.
● Users are free to choose amoung many of GUI's
such as GNOME, KDE.
● More Customizable.
● Any Problem in GUI, we can Kill GUI & Restart
GUI service.


Managing File Permissions

● Setting File Permissions
● Setting File Ownership


File Permission (1)

In linux user can set file permissions, they are
read, write and execute.

If the command ls -l is given, a long list of file
names is displayed.

The first column in this list details the permissions
applying to the file.

If a permission is missing for a owner, group of
other, it is represented by ex: drwxr-x—x


File Permission (2)

Read =4
Write =2
Execute = 1


File Permission (3)

chmod changes the permissions of each given file
according to MODE.

User (rwx) = 4+2+1 = 7
Group(rx) = 4+1 = 5
World (rx) = 4+1 = 5

chmod mode = 755


File Permission (4)

Ex: (1) chmod 444 filename
- Allow read permission to everyone.

(2) chmod 066 filename
- Make a file rw by the group and others.

(3) chmod 777 filename
- Allow everyone to rwx the file.


Setting File Ownership (1)

Change file owner and/or group. `chown' changes
the user and/or group ownership of each given File
to NewOwner or to the user and group of an
existing reference file.

Ex: 1. chown [owner] : [groups] target_file_name
2. chown otc:otc /data1/index.html

3. u – user/owner, g – group/owner, o– all other
r – read, w – write, x – execute
a - for all; user/owner,group and all other


Setting File Ownership (1)

Ex: (3) To change the owner's permissions of a files or directory
chown u+r file.1 chown u+w file.1 chown u+x file.1
chown u-r file.1 chown u-w file.1 chown u-x file.1

Ex: (4) To change the group's permissions of a files or directory
chown g+r file.1 chown g+w file.1 chown g+x file.1
chown g-r file.1 chown g-w file.1 chown g-x file.1

Ex: (5) To change the permissions of a files or directory for
everyone.
chown o+r file.1 chown o+w file.1 chown o+x file.1
chown o-r file.1 chown o-w file.1 chown o-x file.1


User Administration

● Create user
● Delete user
● Create Group
● Delete Group
● Password
● Root login


User Administration (1)

useradd
Allows to create new user accounts
Ex: (1) useradd test

passwd
change the password to the particular user.
Ex: (1) passwd username



groupadd
Allows the user to create new group using the
values specified on the command line.

Ex: (1) groupadd user-name-to-add
groupadd otc



userdel
Delete a user account and realted files
Ex: userdel user-name

groupdel
Delete a group modifies the system files
Ex: groupdel group-name



passwd - passwd is a text file, that contains a list
of the system's accounts.

Often, it also contains the encrypted passwords for
each account.

Example:
passwd username
Enter new UNIX password: ********
Confirm new UNIX password: ********


sudo or su -
sudo (superuser do) allows a system administrator
to give certain users (or groups of users) the
ability to run some (or all) commands as root or
another user while logging the commands and
arguments.

Ex: 1. sudo -i #Enter the Password
- It's use for debian and Ubuntu based linux.
2. su - #Enter the Password
- It's use for Redhat, suse, mandriva based
linux.


File System Management in Linux

● Viewing Mounted Filesystem
● Viewing Diskspace Usage
● Viewing Space by Files
● Viewing Partitions
● Finding Files


Viewing Mounted Filesystem (1)
mount
● Used to view and mount the intend filesystem

● Instruct the kernel to attach the filesystem

● Mount allowed to access all devices, partitions,

CD-ROMs and other storage devices as files.

Ex: (1) mount /dev/sda7 /mnt/
/dev/sda7 – source-directory (hard-disk partition)
/mnt – destination-directory or mount point
Ex: (2) mount -a – Display Mount all filesystems.
Ex: (3) mount -t ext3 /dev/sda6 /diskS


Viewing Mounted Filesystem (2)

umount
reverse process of mounting, i.e unmount the
partition.

Ex: (1) umount /mnt
/mnt – is the place where mount previously.


Filesystem Disk Space Usage

df - Disk Free

● Viewing Filesystem usage
● Viewing Available disk space.

Ex: df -h
-h - print sizes in human readable format
(e.g., 1K, 234M, 2G)


Viewing Diskspace by Files

du – Disk Usage

du (i.e., disk usage) command reports the sizes of
directory trees inclusive of all of their contents and
the sizes of individual files.

Ex: (1) du /sbin/file1
(2) du -h /home


Viewing Partition Table (1)

fdisk – Format Disk
● Menu driven approach

● Creating & manipulate partition tables.

● Partitions are mentioned like /dev/sda

Ex: (1) fdisk -ls
List the partition tables for the specified devices and Size.


Viewing Partition Table (2)

cfdisk

cfdisk is a curses/slang based program for
partitioning any hard disk drive.

Typical values of the device argument are

Ex: (1) cfdisk /dev/sda


Finding Files

grep (Grand Regular Expression)
The grep command searches one or more input
files for lines containing a match to a specified
pattern.

Ex: (1) cat /etc/passwd | grep dso
This searches for pattern specified. In this case all
instances of dso from the /etc/passwd file are
printed.


Finding Files (1)

grep -i “Sample” /home/dsoneil
The -i option makes the search in different
to case (e.g.sample or SAMPLE)


Finding Files (2)

find
● Used to locate files on a Unix or Linux system.

● Search any set of directories you specify for files

that match the supplied search criteria.

Ex: (1) find / -name log -print
- find the file log in the wholo system and
prints it.


who

who
Show who is logged into the system. With no options, list the
names of users currently logged in, their terminal, the time they
have been logged in, and the name of the host from which they
have logged in. An optional system file (default is /etc/utmp) can be
supplied to give additional information.

Ex : 1. who -uH


which

which
which takes one or more arguments. For each of its
arguments it prints to stdout the full path of the
executables that would have been executed when this
argument had been entered at the shell prompt.

Ex: 1. which -a filename

- This will search through all directories in
your current path and find all files named filename


Finding Files (3)

locate
Locate lists files in a database that match a
pattern

Ex: (1) locate wordperfect
The locate command will locate the file specified
and output a directory path.


Process Management in Linux

● Viewing Running Services and Runlevel
● Viewing Running Process
● Killing a Running Process


Viewing Running Process (1)

top
Provides an outgoing look at processor activity
and update dynamically.

Listing of the process based on
● CPU usage

● Memory usage

● Runtime.

Can monitor process belongs to the specific
process id.



Ex:(1) top -p process-id

• Provides the information about process whose
pid is as input.



ps
● Enumerates the currently running processes.
● Process are identified by its id (pid).
● List the Process with its id, state, usage too.

Ex: (1) ps au
a – lists all process
u – select by effective user-id



We can combine ps with grep to find a process by
name.

Ex: (1) ps aux | grep soffice

● Lists the process whose name is soffice.
● List the Process with its id, state, usage too.


Kill a Running Process (1)

● ps is most often used to obtain the PID.
● using pid kill/terminate a unintended process.
● if the PID of a program is found to be 1125
● combine ps with grep to find a process by name.

Ex: kill process-id
(1) Kill -9 1125


Network Management in Linux

● Viewing Networking Configurations
● Viewing Routing Tables
● Viewing Network Services and Ports


Introduction to Networking

Network commands useful when networking with
other computers.

Within the network and across the internet,
obtaining more information about other
computers.


Basic Networking Commands

➔ ifconfig
➔ ping
➔ telnet
➔ dig
➔ nslookup
➔ traceroute
➔ hostname


Viewing Network Configurations (1)

ifconfig
- used to configure and view network
configurations.

Ex: (1) ifconfig -a
- shows the network interface about the
machine.


Viewing Network Connections (2)

ping

Sends an ICMP ECHO_REQUEST packet to the
specified host. If the host responds, you get an
ICMP packet back.

Ex: (1) ping xxx.xxx.xxx.xxx
(xx - ip address or hostname)



telnet
- ability to remotely log in and work on another
computer.

Ex: telnet ip_number port_number

(1) telnet 10.163.14.58 21
also tell whether the port is opened or not.



dig
Is a DNS lookup utility used to perform DNS
lookup and return the output from the internet
servers.

Ex: dig www.gmail.com


Viewing Route Informations (1)

route
Show and manipulate the routing tables. It
manipulates the IP routing table and set up the
routing to the specific hosts in the network.

Allows the user to modify the routing table
manually using add or del options.



netstat
● Output the network statistics includes routing

table tables, interface statistics.
● Print the list of open ports

Ex: (1) netstat -pant

- Will display the currently opened ports in
the system.



traceroute - network diagnostic tool.

traceroute displays each host that a packet
travels through as it tries to reach its destination.

Ex: (1) traceroute www.google.co.in

- Shows each host will be displayed, along
with the response times at each host.



nslookup

Query the internet domain name servers for
getting about the various hosts in the network.

Ex: nslookup domain name
(1) nslookup mail.nic.in


Shell and Remote Copy

● Secure Shell (ssh)
● Secure Copy
● rsync


Secure Shell

ssh
● Allows logging into remote machine
● Provides secure encrypted communications
● Must need an identity

Ex: ssh username@ip-address
(1) ssh otc@10.163.14.100


Secure Copy

scp

● scp copies files between hosts on a network.
● use ssh for data transfer
● provides security as ssh.
● scp will ask for passwords for authentication.

Ex: (1) scp -r /data1
root@10.163.14.58:/home/otc/Desktop


rsync

● rsync is focused on synching data from one disk
location to another.

● rsync remote-update protocol allows rsync to
transfer just the differences between two sets of
files across the network link.

Ex: (1) rsync -avz root@10.163.14.57:/data
/data/tmp


File Archiving in Linux

● File archiving
● Creating Compressed Files


File Archiving (1)

tar
The tar (tape archive) command bundles a bunch
of files together and creates an archive.

Ex: (1) tar -cvf archives.tar archives/
–c - Create a tar file
–v - Verbose Mode
–f - File Name


File Archiving (2)

Ex: (2) tar -tvf archives.tar
To view files in tar file.

Ex: (3) tar -xvf archives.tar
x – Extract the tar contents.

Ex: (4) tar -rvf archives.tar testing.txt
r – Append files to existing tar file.


File Archiving (3)

dd
● whose primary purpose is the low-level copying.

● It can also be used in computer forensics.

● Can snapchot magnetic pattern of an entire disk
needs to be preserved as a byte-exact copy.


File Archiving (4)

Hard Disk Clone

dd if=/dev/sda of=/dev/sdb
'' of '' is the distination and ''if '' is the source.

Partition Clone

dd if=/dev/sda1 of=~/disk2.img
Backing up a hard disk partition is much similar to
backing up a whole hard disk.


File Archiving (5)

Restoring from an Image File

To restore a partition or a hard disk from an image
file, just exchange the arguments "if" and "of"

For example, restore the whole hard disk from the
image file "disk1.img"

Ex (1): dd if=disk2.img of=/dev/sda


zip
zip

The zip program puts one or more compressed files into a
single zip archive, along with information about the files
(name, path, date, time of last modification, protection,
and check information to verify file integrity). An entire
directory structure can be packed into a zip archive with a
single command. Compression ratios of 2:1 to 3:1 are
common for text files. .

Ex: (1) zip -r foo foo.zip


unzip

unzip

Unzip is to extract into the current directory (and
subdirectories below it) all files from the specified ZIP
archive.

Ex: (1) unzip foo.zip foo


Misc

● Debugging
● Time Management Command
● Reboot, Poweroff, Shutdown
● Shells
● Printing
● Man
● Package Installation


Debugging (1)

dmesg

● Display the system control messages from the
kernel ring buffer.

● This buffer stores all messages since the last
system boot, or the most recent ones

Ex: (1) dmesg


Time Management

● hwclock - Set or read the hardware CMOS Clock.
● uptime - reports how long the system is running
● clock - used to set or get current time.
● tset - used to set the users private time Zone.
● w – Lists users currently logged into the system.


Printing System

● CUPS - Common UNIX Printing System

●CUPS is a open source printing system developed
by Apple Inc.

● CUPS is the software use to print from
applications.


Printing System (1)

● Access the Web Interface for Printing.

● CUPS provides a web interface, that allows you
to view print jobs, printers, and the online help,
as well as manage your printers.

● The CUPS web interface is available on your
machine at the following URL:

● http://localhost:631


Printing System (2)
lpr
submits files for printing, If no files are listed on
the command-line, lpr reads the print file from the
standard input.

Ex: (1) lpr /home/html/index.html
– This command will print the file index.html to the printer.

(2) lprm 12
– This command will cancel pint job 12 in the printer queue.

(3) lpq
– Show the contents of the print queue.


man

man is the system’s manual pager. Each page
argument given to man is normally the name of a
program, utility or function. The manual page
associated with each of these arguments is then
found and displayed. A section, if provided, will
direct man to look only in that section of the
manual. The default action is to search in all of
the available sections, following a pre-defined
order and to show only the first page found, even
if page exists in several sections.


PACKAGE INSTALLATION

Install packages from source

The installation procedure for software that comes
in tar.gz and tar.bz2 packages isn't always the
same, but usually it's like this:

# tar xvzf package-name.tar.gz
# cd package-name
# ./configure
# make
# make install


PACKAGE INSTALLATION (2)

Install package from ubuntu repository

# sudo apt-get update
- update ubuntu repository
# sudo apt-get install <Package Name>
# sudo apt-get install apache2
- Install apache webserver from repository


PACKAGE INSTALLATION (3)

Remove Package

# sudo apt-get remove apache2
- remove packages from system

# sudo apt-get remove --purge apache
- remove packages with configuration files.


Server

● Apache Webserver
● PostgreSQL
● OpenSSH Server
● DHCP Server
● FTP Server


APACHE SERVER

● Web server
● Fully open source
● Developed by Apache Software Foundation
● Directives that control the configuration of Apache.
● Secure Sockets Layer.


POSTGRESQL SERVER

PostgreSQL is a powerful, open source relational database
system.

It runs on all major operating systems, including Linux, UNIX (AIX,
BSD, HP-UX, SGIIRIX, Mac OS X, Solaris, Tru64), and Windows.

PostgreSQL boasts sophisticated features such as Multi-Version
Concurrency Control (MVCC), point in time recovery, tablespaces,
asynchronous replication, nested transactions (savepoints).

Packages for PostgreSQL come with many Linux distributions, and
it can be compiled and installed on almost all varieties of Unix.


POSTGRESQL SERVER

PostgreSQL consists of a server process that reads and writes the
actual database files, and a set of client programs that
communicate with the server.

All of the PostgreSQL database files are stored under a directory
such as /var/lib/pgsql or /usr/local/pgsql.

The most important is pg_hba.conf, which lists client hosts that are
allowed to connect to the server.

This module allows an administration to manage databases,
tables, fields and records in a PostgreSQL server.


OpenSSH Server

Secure Shell or SSH is a network protocol that allows
data to be exchanged using a secure channel between
two networked devices.

Ex: 1. ssh user@host

2. ssh -p user@host
– connect to host on port as user.
3. ssh-copy-id user@host
– add your key to host for user to enable a keyed or
passwordless login.


DHCP SERVER

● DHCP - Dynamic Host Configuration Protocol.

● Provides advanced IP address allocation and
management for TCP/IP LAN computing environments.

● This protocol saves the system administrator much time
having to manually configure each host workstation
manually, and to maintain large databases storing IP
assignment details.


FTP SERVER

● FTP (File Transfer Protocol) is the simplest and most
secure way to exchange files over the Internet.

● The most common use for FTP is to download files
from the Internet.

FTP Types:
● Active

● Passive

● Asynchronous


Q/A SESSION


Thank you


Advance linux presentation_0702011

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