The document provides information about the Ubuntu operating system. It discusses Ubuntu's history as a fork of Debian Linux that was created to be more user-friendly. It was founded by Mark Shuttleworth in 2004. The document also covers Ubuntu's design principles, use of the Linux kernel for processes, memory management, file systems, security features, and graphical user interface.

1. UBUNTU
A Project Presented to the Faculty of the
College of Information Technology and Computer Science
University of the Cordilleras
In Partial Fulfillment
of the Requirements for the Degree
BACHELOR OF SCIENCE IN INFORMATION TECHNOLOGY
By
JACQUILINE TABELIN COLLINS
JONAH MAE BELENO REPUBLICA
July 29, 2015
History: As mentioned previously, Ubuntu is one of a number of
Linux distributions. The source code that makes up the Ubuntu

2. Linux distribution originates from another, much older Linux
distribution known as Debian (so called because it was started
by two people named Debra and Ian). Debian is still a widely
respected operating system but came under criticism for
infrequent updates and less than user friendly installation and
maintenance (though these areas have shown improvement
recently).
A South African internet mogul (who made his fortune selling his
company to VeriSign for around $500 million) decided it was time
for a more user friendly Linux. He took the Debian distribution
and worked to make it a more human friendly distribution which
he called Ubuntu. He subsequently formed a company called
Canonical Ltd to promote and provide support for Ubuntu Linux.
In addition Shuttleworth has formed and funded (to the tune of
$10 million) a foundation to guarantee the future of Ubuntu.
The rest, as they say, is history. Ubuntu has since gone from
strength to strength. Dell and other hardware vendors now ship
computers pre-loaded with Ubuntu Linux and Ubuntu usually tops
the chart atDistroWatch.com (a web site which tracks the
popularity of the various Linux distributions).
If you are new to Linux, or already use Linux and want to try a
different Linux distro it is unlikely you will find a better
option than Ubuntu Linux.
Transcript of "Ubuntu OS Presentation"
1. 1. Presentation on the Ubuntu Operating System Colorado
Technical University CS 340 – Operating Systems October
2010 Loren Karl Schwappach
2. 2. Overview Introduction  Security History  Hacking
Design Principles  Networking Process Management 
Robustness Memory Management  Interface Process
Communication  Basic Commands Deadlock Handling  System
Hardening File System  Summary
3. 3. IntroductionUbuntu 10.10• Secure, Super-fast, and great-
looking• Open source, free, & widely distributed• Suitable
for server and desktop use.• Includes > 1000 pieces of
software• Ubuntu One Personal Cloud• Linux kernel version
2.6 w/ Gnome 2.16Support for:• Intel x86 (IBM-compatible
PC)• AMD64 (Hammer)• PowerPC (iBook, Powerbook, G4,
G5)http://www.ubuntu.com/desktop/features

3. 4. 4. History• 1991, Linus Torvalds (a Finnish student) writes
a opensource small, self-contained kernel (Linux) for the
80386processor.• Version 0.01 - no network support, basic
VMsubsystem, support for Minix fs and limited device-
driversupport. [1]• 1994, Version 1.0 - networking (TCP/IP
protocols, newfile system, SCSI, floppy disks, CD-ROM
devices, soundcards, mice, keyboards, floating point
emulation, UNIX-style IPC and extended VM subsystem. [1]•
1996, Version 2.0 - PCI support, 80386 CPU virtual8086 mode
, memory management improvements, ISDN,internal kernel
threading, automatic module loading andmultiprocessor
support. [1]• 1999, Version 2.2 - firewalling, routing and
trafficmanagement, improved symmetric multiprocessor
(SMP)performance and (Acorn, Apple, and NT) disk support.
[1]http://en.wikipedia.org/wiki/Linux_kernel
5. 5. HistoryUbuntu - Debian GNU/Linux distribution.•
Originally released under name “no-name-yet.com.”• Ubuntu -
African word that means “humaneness.”• 2004, 1st publicly
released version
4.10http://en.wikipedia.org/wiki/List_of_Ubuntu_releasesVar
iants include :• Edubuntu (designed for school
environments)• Kubuntu (Uses KDE GUI environment)•
Mythbuntu (Home Theater TVs)• Ubuntu Studio (Professional
AV editing software)• Xubuntu (uses XFCE desktop
environment)• 2010, Latest version 10.10 Maverick Meerkat:•
Linux Kernel version 2.6.35Software:• OpenOffice, Firefox,
Empathy IM, Transmission (BTclient), Gimp, games, and
more.• Desktop version supports Intel x86 and AMD64
.http://www.ubuntu.com/desktop/why-use-ubuntu
6. 6. HistoryLinux kernel size as an indicator of complexity
7. 7. Design PrinciplesUbuntu’s Linux kernel (2.6):Multiuser,
multitasking system w/ complete set of UNIX-compatible
tools.Linux supports the Portable Operating System
Interface[for Unix] (POSIX) threading extensions (Pthreads
and asubset of the POSIX extensions for real time
processcontrol. [1]The Linux system three bodies of
code:Kernel – Maintains OS abstractions, virtual memory
andprocess management. [1]System Libraries – Standard set
of functions forapplications to interact with the kernel.
[1]System utilities – Programs that perform
individual,specialized management tasks. [1]
8. 8. Design PrinciplesKernel• Ability to load/unload sections
of code on demand.Three components to the module support :•
Module management (allows loading modules in mem)• Driver
registration (allows modules to tell kernel when newdrivers
are available)• Conflict-resolution.Driver Registration
tables include the following:• Device Drivers – Character

4. devices (printers, terminals,mice), block devices (disk
drives), and network interfacedevices. [1]• File Systems –
Anything that implements Linux’s virtual-file-system call
routines. [1]• Network protocols – IPX, firewall packet
filtering rules, etc.[1]• Binary format – specifies way for
recognizing/loading anexecutable file. [1]
9. 9. Process ManagementLinux process properties generally
fall into three groups:Process Identity consists of:Process
IDCredentials (associated UID/GIDs)Personality (modifies
semantics of sys calls (unique to Linux)).Process
environment (inherited from parent) is composed of:Argument
vector (lists command line arguments)Environment vector
(list of NAME=VALUE pairs).Process context (state of
program in time) includes:Scheduling context – Information
to suspend and restart theprocess. Includes: process
registers, floating point registers,scheduling priority,
and process’s kernel stack)Accounting – Information about
resource usageFile table – array of pointers to kernel file
structuresSignal-handler table – Asynchronous handling of
external events.Virtual memory context – describes content
of address space
10. 10. Process ManagementLinux kernel 2.6 Scheduling:• 2
Algorithms Used: Time Scheduling and Real Time• Uses FIFO &
round robin real time scheduling• Real Time Priorities are
from 1-100
11. 11. Memory ManagementLinux avoids segmentation and
separates physicalmemory into three zones:ZONE_DMA (lower
16MB of physical memory),ZONE_NORMAL (normally used 16-896
MB),ZONE_HIGHMEM (Not mapped into kernel addressspace >
896MB). [1]Page tables keep track of the physical pages of
memorythat are used by a process, and they map the
virtualpages to the physical pages.Linux kernel 2.6 uses
reverse page mapping
12. 12. Memory ManagementVirtual memory manager:•
Responsible for maintaining the address spacevisible to
each process.• Creates pages of virtual memory on demand
andmanages loading of pages to/from disk.• Views a process
address space as independentseparate regions and as
independent separate pages.• Reserves its own internal use,
architecturedependant region of virtual address space for
everyprocess.Paging system divided into two sections:•
Policy algorithm (decides which pages to write todisk and
when to write them)• Paging mechanism (carries out
transfers and pagesdata back into physical memory when
needed).
13. 13. Memory ManagementMMU (Memory Management Unit) –
allows softwareto reference physical memory by aliased

5. addresses(using pages and page tables)Zoned Buddy Allocator
– responsible for pageallocations. Manages list of physical
contiguous pagesand maps them to MMU page tables &
managesmemory zones.Slab Allocator – Allows flexible memory
sizes (Thanstandard 4kb page) by creating cache
objects.Kernel Threads – Recovery and management ofmemory
(kscand, kswaped, kupdated, bdflush)
14. 14. Memory Management High Level Overview of VM System
VM Page State Machine
15. 15. Process CommunicationSignals - Sent by other
processes or the kernel to a specific process to indicate
variousconditions.Pipes - Unnamed pipes set up by the shell
normally with the "|" character to routeoutput from one
program to the input of another.FIFOS - Named pipes
operating on the basis of first data in, first data
out.Message queues - Message queues are a mechanism set up
to allow one or moreprocesses to write messages that can be
read by one or more other processes.Semaphores - Counters
that are used to control access to shared resources.
Thesecounters are used as a locking mechanism to prevent
more than one process fromusing the resource at a
time.Shared memory - The mapping of a memory area to be
shared by multiple processes.
16. 16. Deadlock HandlingDeadlock - a condition where one
or more executing threads and one or more resources,such
that each thread is waiting for one of the resources, but
all the resources are alreadyheld. [1]In essence the
threads are all waiting for each other, but they will never
make anyprogress toward releasing the resources that they
already hold.Unlike some Operating Systems:“There is no
deadlock detection for applications or threads by the Linux
kernel”.Linux requires the use of semaphores (sleeping
locks), spin locks (a lock that can be heldby at most one
thread of execution), and the Big Kernel Lock (BKL) to
attempt deadlockprevention.
17. 17. Deadlock HandlingLinux kernel version 2.6 used by
Ubuntu 10.10 introduces:A new type of lock called a seq
lock (sequence lock).• Works by maintaining a sequence
counter..• Whenever the in question data is written to, a
lock is obtained and a sequencenumber is incremented.•
Prior to and after reading the data, the sequence number is
read. If the values arethe same, then a write did not begin
in the middle of the read.
18. 18. File SystemLinux 2.6 retains UNIX’s standard file-
system module.• Allows Linux files to be anything capable
of handling the input or output of astream of data.• Device
drivers, interprocess communication channels and network

6. connectionsall look like files on Linux.• The Linux kernel
hides the implementation details of any single file type
behind alayer of software called the virtual file system
(VFS). [1]The VFS defines four major types of objects:•
inode object – represents an individual file.• file object
– represents an open file.• superblock object – represents
the entire file system.• dentry object – represents an
individual directory entry.
19. 19. File SystemXFS was a file system:Developed by
Silicon Graphics and designed to handle files as large as a
million terabytes,in 32 bit Linux systems it can handle
files up to 16 terabytes.Ext4 is currently the default
choice of Ubuntu 10.10 and performs much better than
ext2,ext3, and XFS. A new file system btrfs is also
supported in Ubuntu version 10.10 but is notyet stable
[9]Ext4 (forth extended file system) - journaling (keeps
track of changes in a journal beforechanging in main file)
Linux file system that became stable in 2008.Ext4 :•
Supports volumes up to 1 Exabyte (1018) and files with
sizes up to 16 terabytes(16x1012). Uses extents (range of
contiguous physical blocks) to replace the traditionalblock
mapping used by ext2/3, performs pre-allocation of on-disk
space, delayedallocation (using an allocate-on-flush
technique), breaks the ext3 32,000 subdirectorylimit (now
64,000), performs journal check-summing (improved
reliability), faster filesystem checking, multi-block
allocation, and improved timestamps.
20. 20. File System
21. 21. SecurityThe Linux security module is closely tied
to UNIX security mechanisms.Security concerns can be
classified into two groups:Authentication (Ensuring that
only authorized individuals have access to files that
theyare authorized.)Access control (mechanism for
validating whether a user has the right to access
aparticular object and preventing unauthorized access as
necessary). [1]Historically Linux suffered from the same
security vulnerabilities (such as eight characterpasswords)
as UNIX. However, a newer security mechanism known as the
Pluggableauthentication Module (PAM) system based on shared
libraries is now available to Linuxusers. [1]
22. 22. SecurityEvery object in a UNIX system under user
and group access control has a single UID andGID associated
with it. User processes have a single UID but may have more
than oneGID.Linux performs access control by assigning
objects a protection mask that specifies whichaccess modes
(read, write, or execute) can be granted to the user. The
only exception isthe root UID which is granted automatic

7. access to any object in the system.Linux allows use of the
setuid command to run programs with different user
privledges(for example lpr has access to the print queue
even if the user does not).This can be useful but can also
pose security concerns for the operating system.
23. 23. HackingBrute-force (password guessing) attacks are
the most common form of attack on anyoperating system. In
Linux, the most common types of services that can be brute-
forceattacked are: [4]• Telnet• File Transfer Protocol
(FTP)• The “r” commands (rlogin, rsh, and so on)• Secure
Shell (ssh)• SNMP community names• Post Office Protocol
(POP) and Internet Message Access Protocol (IMAP)•
Hypertext Transport Protocol (HTTP/HTTPS)• Concurrent
Version System (CVS) and Subversion (SVN)
24. HackingHydra is one of the most popular and versatile
brute force utilities available. However pop.c and SNMP
brute are also popular and can be downloaded at the
following locations: [4]THC – Hydra
http://freeworld.thc.org/thc-hydra/pop.c
http://packetstormsecurity.org/groups/ADM/ADM-
pop.cSNMPbrute
http://packetstormsecurity.org/Crackers/snmpbrute-fixedup.c
25. Hacking According to Hacking Exposed 6: Network Secrets
& Solutions [4] there are some free ware tools that can
help prevent brute force attacks. For brevity I will not
list the download locations (use Google search). These
tools listed in the book follow: crack lib Password
composition tool password a replacement for the password
command. Secure Remote Password a new mechanism for
performing secure password based authentication and key
exchange over any type of network. Open SSH A
telnet/ftp/rsh/login communication replacement with
encryption and RSA authentication. pam_passwdqc PAM module
for password strength checking.pam_lockout PAM module for
account lockout.
26. NetworkingLinux supports the entire standard internet
protocolsused for most UNIX to UNIX communications as well
asmany of the protocols native to non-UNIX
operatingsystems.Internally, networking in the Linux kernel
isimplemented in three layers of software: The
socketinterface, protocol drivers, and network-device
drivers.The most important set of protocols in Linux is
theTCP/IP protocol suite containing (IP, UDP, TCP, and
ICMP)protocols.Linux also performs firewall management of
IP traffic.
27. Networking

8. 24. 28. RobustnessA comparison of operating system
robustness wascompleted for the 19th International
Symposium onSoftware Reliability Engineering by Shanghai
Jiao TongUniversity [8].They observe that Windows XP
achieves betterrobustness performance than Ubuntu in
theirexperiment.Ubuntu had higher restart and abort rates
thanWindows OSs in general robustness test.In particular,
the robustness of Ubuntu rose drasticallyfrom 85.70% to
97.24% in CINT (surpassing WindowsVista in this generic
compute intensive operationalprofile) and 97.37% in CFP.”
[8]
25. 29. Robustness
26. 30. InterfaceUbuntu 10.10 uses the GNU Network Object
ModelEnvironment (GNOME) graphical user interface. It
hasthe look and appeal of Windows Vista without many ofthe
problems.It also uses a command line interface.
27. 31. Basic Commands Some Important Directories Found in
UbuntuDirectory Description/bin Frequently used system
binaries/dev Special drivers for I/O devices/etc
Miscellaneous system administration parameters/lib
Frequently used libraries/tmp Temporary files once stored
here/usr Contains all user files in this part of the
tree/usr/include System-provided header files/usr/man On-
line manuals/usr/spool Spooling directories for printers,
e-mail, and other daemons
28. 32. Basic Commands Some Popular Utility Programs Found
in UbuntuCommand Descriptionawk A pattern matching
languagebasename Strip off prefixes or suffixes from a file
namecat Link file(s) and write them to standard outputcc
Compile a C programchmod Change protection mode for
file(s)comm. Print lines common to two sorted filescp Make
a copy of a filecut Make each column in a document into a
separate filedate Print the date and timediff Print all the
differences between two filesecho Print the arguments (used
mostly in shell scripts)find Find all the files meeting a
given conditiongrep Search file(s) for lines containing a
given patternhead Print the first few lines of file(s)kill
Send a signal to a processlp Print a file on a printerls
List files and directoriesmake Recompile those parts of a
large program that have changedmkdir Make a directorymv
Rename a file or move file(s)paste Combine multiple files
as columns in a single filepwd Print the working
directoryrm Remove file(s)rmdir Remove one or more
directorysed A stream (i.e., noninteractive) editorsty Set
terminal options such as the characters for line
editingsort Sort a file consisting of ASCII linestail Print
the last few lines of a filetr Translate character

9. codesuniq Delete consecutive identical lines in a filewc
Count characters, words, and lines in a file
29. 33. System HardeningMost Linux systems use two boot
loaders, the Linux Loader (LILO) or Grand Unified
BootLoader (GRUB). Ubuntu uses GRUB. The boot loader
controls your boot image anddetermines what kernel is
booted when the system is started or rebooted. [3] Both
boot loaders are insecure if a hacker has physical system
access andTurnbull recommends that users only keep the
current and previous versions of thekernel. Both boot
loaders can easily be secured with passwords. To accomplish
thisUbuntu’s GRUB do the following: *3+superman# grubgrub>
md5cryptPassword: ********Encrypted:
$1$2FXKzQ0$I6k7iy22wB27CrkzdVPe70grub> quitNow copy the
encrypted output and add the password to your grub.conf
configurationfile. You can also add the --md5 option prior
to the password in grub.conf to ensureinteraction with GRUB
can only occur when you type p and enter the required
password.
30. 34. System HardeningMost Linux systems use two boot
loaders, the Linux Loader (LILO) or Grand Unified
BootLoader (GRUB). Ubuntu uses GRUB. The boot loader
controls your boot image anddetermines what kernel is
booted when the system is started or rebooted. [3] Both
boot loaders are insecure if a hacker has physical system
access andTurnbull recommends that users only keep the
current and previous versions of thekernel. Both boot
loaders can easily be secured with passwords. To accomplish
thisUbuntu’s GRUB do the following: *3+superman# grubgrub>
md5cryptPassword: ********Encrypted:
$1$2FXKzQ0$I6k7iy22wB27CrkzdVPe70grub> quitNow copy the
encrypted output and add the password to your grub.conf
configurationfile. You can also add the --md5 option prior
to the password in grub.conf to ensureinteraction with GRUB
can only occur when you type p and enter the required
password.
31. 35. System HardeningThere are also several services
that may start at boot, of which many can pose as
securityrisks. Turnbull [3] recommends disabling the
following:anacron, apmd, atd, autofs, cups, gpm, irda
(unless used), isdn (unless used), kudzu, lpd,netfs, nfs,
nfslock, pcmcia, portmap, rawdevices, rhnsd, snmpd,
snmtptrap,winbind, xfs,ypbind.Delete the following user
accounts: adm, desktop, ftp, games, gdm, gnats, gopher,
identd, irc, list (if not usingmailman), lp & lpd (if no
printing) mailnull (if no Sendmail), news, nfsnobody,
nscd,operator, postgres (if no Postgres), proxy, rpc,

10. rpcuser, sync, telnetd, uucp, www-data (ifnot Web
server).Delete the following group accounts: lp, news,
uucp, proxy, postgres, www-data, backup, operator, list,
irc, src, gnats,staff, games, users, telnetd, gdm, telnetd,
gopher, ftp, nscd, rpc, rpcuser, nfsnobody, xfs,desktop
32. 36. SummaryThis briefing looked into the history and
features of the Ubuntu Operating system as wellas exploring
the mechanics that make the Ubuntu operating system
unique.This briefing further dug deep into:Design
principles (specifically the Kernel, System libraries, and
System utilities)Process management (process context
includes: scheduling context, accounting, filetable,
signal-handler table, and virtual memory context)Memory
management (physical memory zones, allocation of memory
using pages, andmemory mapped to the address space)Process
communication (signaling, use of semaphores, piping, and
shared-memory)Deadlock handling (no detection for
applications or threads by the Linux kernel, useslocks for
prevention)File system (VFS, inodes, file objects,
superblocks, dentry objects, extfs, and ext4)Security
(authentication and access control)Networking (socket
interface, protocol drivers, and network-device
drivers)Program interface (Gnome GUI, and applications)And
more.. (Hardening, Robustness, Common Commands, etc..)
33. 37. Questions?
34. 38. References1. Silberschatz A., Galvin P., Gagne G.
(2009). Operating System Concepts (pp. 801-843). 8th
edition. Hoboken, NJ. John Wiley & Sons.2. Michael S.,
(2001). The Linux Codebook: Tips and Techniques for
Everyday Use. San Francisco. No Starch Press, Inc.3.
Turnbull J., (2005). Hardening Linux. New York, NY.
Springer-Verlag New York, Inc.4. McClure S., Scambray J.,
Kurtz G., (2009). Hacking Exposed 6: Network Security
Secrets & Solutions (pp. 223-315). New York, NY. McGraw
Hill.5. Saur K., Grizzard J., Locating x86 Paging
Structures In Memory Images. “Digital Investigation” Volume
7 (2010): pages 29-30. SciDirect Database. Accessed 7 Dec
2010.6. Lien Y., 4: Operating Systems. Academic Press
(2005): pages 355-366. SciDirect Database. Accessed 8 Dec
2010.7. Narayan S., Shang P., Fan N., Performance
Evaluation of IPv4 and IPv6 on Windows Vista and Linux
Ubuntu. (2009) International Conference on Networks
Security, Wireless Communications and Trusted Computing.
IEEE Database. Accessed 9 Dec 2010.8. Ju X., Zou H.,
Operating System Robustness Forcast and Selection. 19th
International Symposium on Software Reliability
Engineering. IEEE Database (2008). Accessed 10 Dec 2010.9.

11. Tozzi C., 2010, Ubuntu 10.10’s New File System. The Var Guy
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http://www.thevarguy.com/2010/08/02/ubuntu-10-10s-new-file-
system-btrfs/