Tuesday, November 22, 2011

How to avoid worst passwords in online security

This list of worst passwords compiled by SplashData. They are used in web sites, desktop applications and on mobiles and even in programs that help keep passwords secure. But with passwords like these below your security and privacy is under frequent threat:

1. password
2. 123456
3. 12345678
4. qwerty
5. abc123
6. monkey
7. 1234567
8. letmein
9. trustno1
10. dragon
11. baseball
12. 111111
13. iloveyou
14. master
15. sunshine
16. ashley
17. bailey
18. passwOrd
19. shadow
20. 123123
21. 654321
22. superman
23. qazwsx
24. michael
25. football
26. abc
27. goodboy
28. userid
29. userid1

Here are some tips to have strong passwords

1.Strong Master Password
Create a strong master password for your main email

2.Randomize Passwords
Use random passwords for websites with lengths of 15-20 . if you dont use them always, you can ask to send password to your master email.

2. Protect your master account. Never keept it's password on phone or your text book. Keep it in your mind and safe at home.

4. Dont reuse passwords in different accounts.

5.User IDs
Consider randomizing your username depending on what you are protecting. Never use your online banking user id anywhere.

5.Secret Qusetion
Your friends and relatives knows answers to default questions given by google and yahoo. Create your own privcy. What was my favorite food, drink when I was ill? combine information in a question. And make it random.

Username: 88N1iRQ1o9XM1Xi#4KLs
Password: [yBNSkG%/8r!:[g8O9N6

Use unicode characters from other languages
Use slangs from your own locality
Never use anything in dictionaries
Never use 123 or abc anywhere
Dont keep your passwords only in memory, have a recovery mechanism

Privacy Guide on Facebook

Privacy Settings
Once logged into your account on Facebook,
Goto Account> Privacy Settings
1.Everyone - public with no restriction be carefull with this option
2.Friends of Friends - tricky , your friends may have fake friends
3.Friends Only - Make sure you know them and not fake ones
Account > Privacy Settings > Customize Settings > Things I Share

Pay a special attention to "Posts by me"
Account > Privacy Settings > Customize Settings > Things Others Share
What you actually want to see, make sure you don't waste your time

Account > Privacy Settings > Customize Settings > Contact Information

Omit your Email Address and Phone Number
Account > Privacy Settings > Customize Settings > Things I Share > Posts by Me
Select "Custom" and set your privacy requirement

Account > Privacy Settings > Customize Settings > Things Others Share > Photos and videos you're tagged in
Account > Privacy Settings > Customize Settings > Things Others Share > Suggest photos of me to friends
Account > Privacy Settings > Customize Settings > Things Others Share > Friends can check me in to Places
Account > Privacy Settings > Customize Settings > Things I Share > Edit privacy settings for existing photo albums and videos
Account > Privacy Settings > Apps, Games and Websites
Account > Account Settings > Account Security
Account > Account Settings > Facebook Ads
Edit my Profile
My Wall
Public Directory

1. Don't assuem that your virus guard to protect you 100%.

2. Don't Accessing an account through an e-mail link to provide sensitive information.
Criminals using “phishing” scams use emails to steal your logins, account numbers and other sensitive data. The web you use would look like genunie with same design and have a url like somedomain.com/facebook or even facebook1.com to disguise.
They look legitimate to users who are busy. "it’s pretty much impossible for people to know … if the e-mail is real or not" says an expert.

3. Use multiple passwords
If you use one password for all accounts and  If somebody manages to get hold of your password … they will have entry into all your accounts and impersonate you.

4. Downloading free software
Free software is good. Only download software from places you know are safe like sourceforge, cnet etc. Some “free” software comes loaded with spyware. They hijack your browser, port 80 and employs keystroke-capture programz to steal your personal data.

5. don't Click on pop-up ad that says your PC is not secure
They take you to spyware sites or have malicious software downloaded to your computer.
Instead, click on the tiny “close” button in the right corner. Best is to enable your browser’s pop-up blocker.

6. Don't use debt cards to Shop online
Use a separate card for your online purchases. Don’t shop online with debit cards, if stolen they offer no liability protection.

7. https and httpMake sure when you are entering your address and credit card information, that the site’s URL says “https”. https offers greater security than “http.”

Saturday, November 19, 2011

OSI (Open Systems Interconnect) Model Animation

The Open Systems Interconnection model (OSI model) introduced by International Organization for Standardization. It standardizes the functions of a communications system in terms of layers. OSI groups similar communication functions into logical layers. An instance of a layer provides services to its upper layer instances while receiving services from the layer below.

For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path.

Layer 1: Physical layer
defines electrical and physical specifications for devices.
defines the relationship between a device and a transmission medium, such as a copper or optical cable, including the layout of pins, voltages, cable specifications, hubs, repeaters, network adapters and more.

Establishment and termination of a connection to a communications medium.
Sharing communication resources effectively among multiple users.
Modulation (conversion from and to digital)

Layer 2: data link layer
Provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer.

IEEE 802.3 dominant wired LAN protocol (ETHERNET)
IEEE 802.11 the wireless LAN protocol

Layer 3: network layer
Provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network.
Performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. Routers operate at this layer, sending data throughout the extended network and making the Internet possible.

Layer 4: transport layer
Provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. The transport layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Some protocols are state- and connection-oriented. This means that the transport layer can keep track of the segments and retransmit those that fail. The transport layer also provides the acknowledgement of the successful data transmission and sends the next data if no errors occurred.

Transport layer is like a Post Office, which deals with the dispatch and classification of mail and parcels sent. The post office manages the outer envelope of mail. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only.

The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI.

Layer 5: session layer
Controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for graceful close of sessions, which is a property of the Transmission Control Protocol, and also for session checkpointing and recovery, which is not usually used in the Internet Protocol Suite. The session layer is commonly implemented explicitly in application environments that use remote procedure calls.

Layer 6: presentation layer
Establishes context between application-layer entities, providing independence from data representation (e.g., encryption) by translating between application and network formats. The presentation layer transforms data into the form that the application accepts.

Converting an EBCDIC-coded text file to an ASCII-coded file, or serialization of objects and other data structures from and to XML.

Layer 7: application layer
The application layer is the OSI layer closest to the end user, which means that both the OSI application layer and the user interact directly with the software application. Application-layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. Synchronizes communication between applications requires cooperation that is managed by the application layer.

Some examples on TCP/IP stack:
  • Hypertext Transfer Protocol (HTTP),
  • File Transfer Protocol (FTP),
  • Simple Mail Transfer Protocol (SMTP)
  • Simple Network Management Protocol (SNMP).

Important Combinational Logic Circuits

1.0 Decoder
Translates an n-bit input codeword into a larger m-bit output word,
where m is 2^n

2. Multiplexer (MUX)
Connects one of 2^n input data lines to one output line.

3. Demultiplexer (DeMUX)
Connects one input data line to one of 2^n
output lines.

4. Read-Only Memory (ROM)
A programmable truth table with n-bit address input and (selects a row), m-bit data output (typically m = 8, for one row)

5. ROM Types
Decoder (selects a word)
Encoder array (encodes or stores the word)
Diode-fuse array
MOS transistor-fuse array
Double gate MOS transistor array

6. ROM implementations.
a. ROM (mask)
b. PROM (programmable ROM):
c. EPROM (erasable-programmable ROM):
d. EEPROM (electrically-erasable PROM):
e. Flash (fast block-based EEPROM)

7. Random Access Memory (RAM) is a Rewritable truth table of cells

8. SLC
Are logic circuits whose outputs dpend upon state.

a circuit that has two stable states and can be used to store state information.
The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs.

9. Clocks
Outputs yield uniform rectangular waveforms when plotted against time.
Clock frequency = number of complete clock oscillations (cycles) per
second of time, expressed in Hertz or cycles per second (Hz=cycles/sec)

10 Ripple counter
a single JK-type flip-flop, with input fed from its own inverted output. This counter will increment once for every clock cycle
Asynchronous (ripple) counter – changing state bits are used as clocks to subsequent state flip-flops
Synchronous counter – all state bits change under control of a single clock
Decade counter – counts through ten states per stage
Up/down counter – counts both up and down, under command of a control input
Ring counter – formed by a shift register with feedback connection in a ring

11. Data Transfer Modes

12.0 Data Latch Register
a register circuit capable of performing only PIPO data transfers.

13. Shift Register
register circuit capable of performing SISO data transfers.

14. Bidirectional shift registers
contain additional logic circuitry to support left or
right data shifts.

An Algorithm to convert Decimal to any base

B=2 #base
place = 0
number = 105 #number to be converted

while (number > 0 )
digit[place] = number mod B
number = number div B
place = place + 1
} loop here

print digit[]

Write a python code for this

Friday, November 18, 2011

How Software agents work?

Software agents are computer programs that have specialized purpose and assigned tasks.

They can perform simple and repetitive tasks faster than human workers. They can be used for personal or commercial purposes, but can also be used in malicious attacks on users.

Google uses software agents (spiders/robots) to periodically visit web sites to index them in google search engine. An e commerce agent finds the best price for a phone model on e commerce sites

A Search engine Spider Simulator

Online chat agents search answers to keywords in a database to help users asking questions

A chatbot is a a computer program designed to simulate an intelligent conversation with human users.
Most chat bots simply scan for keywords within the input and pull a reply with the most matching answer from a database.


search engines use robots to index web pages

Software agents (Bots) can be used to spread spam emails, viruses and scams.
Software Update Agents (Virus Guards)

How Googlebot Works ?
Google's algorithm assigns a rank to each page based several factors,
1. how many times the keywords appear on the page.
2. Google looks for keywords in headings. K
3. Keywords in larger headings are more valuable than smaller headings
4. Google assigns a page rank every search result.
5. Search Position depends partially on number of other Web pages linking to target page. (vote)
6. Votes from a high-ranking Web page counts more
7. The more links a Web page sends out, the more diluted its voting power becomes.
Software Agents used in personalised information management, e commerce, interface design, computer games, and complex industrial processes. They are computer programs that can be delegated to do some tasks. They are mostly self-contained programs capable of controlling its own decision making and acting, based on its environment.


More :
Gopher agents:Execute straightforward tasks based on pre-specified rules and assumptions
- Inform when temperature rises by 10% from its mean position.
- Alert reorder stock items
Service performing agents
Execute a well defined task at the request of a user
- find the cheapest flight to Colombo

Predictive agentsProvides information or services to a user, without being asked
- monitor newsgroups on the INTERNET and return relevent discussions
• Autonomy: able to perform majority of tasks without direct human intervention and have a degree of control over their own actions and their own internal state.
• Social ability: able to interact, when appropriate, with other software agents and humans to solve problems
• Responsiveness: agents should understand their environment and respond to changes
• Proactiveness: agents takes automatic action where appropriate.

Boolean Algebra & Logic Gates for A/L ICT

Boolean algebra or Boolean logic is a calculation of truth values, developed by George Boole in the 1840s. In ICT it resembles logical multiplication xy, addition x + y, and negation −x to build combined circuits.

Boolean logic or Boolean algebra is a logical calculus which has only two values, 'true' or 'false'.
Boolean Logic is defined as a logical system of operators - 'AND', 'OR' and 'NOT'. It is a way of comparing individual bits and used in computer construction, switching circuits, etc.

' denotes negative
Boolean Algebra Quiz

1. Give the relationship that represents the dual of the Boolean property A + 1 = 1?
(Note: * = AND, + = OR and ' = NOT)
1. A * 1 = 1
2. A * 0 = 0
3. A + 0 = 0
4. A * A = A
5. A * 1 = 1

2. Give the best definition of a literal?
1. A Boolean variable
2. The complement of a Boolean variable
3. 1 or 2
4. A Boolean variable interpreted literally
5. The actual understanding of a Boolean variable

3. Simplify the Boolean expression (A+B+C)(D+E)' + (A+B+C)(D+E) and choose the best answer.
1. A + B + C
2. D + E
3. A'B'C'
4. D'E'
5. None of the above

4.Which of the following relationships represents the dual of the Boolean property x + x'y = x + y?
1. x'(x + y') = x'y'
2. x(x'y) = xy
3. x*x' + y = xy
4. x'(xy') = x'y'
5. x(x' + y) = xy

5.Given the function F(X,Y,Z) = XZ + Z(X'+ XY), the equivalent most simplified Boolean representation for F is:
1. Z + YZ
2. Z + XYZ
3. XZ
4. X + YZ
5. None of the above

6. Simplification of the Boolean expression (A + B)'(C + D + E)' + (A + B)' yields which of the following results?
1. A + B
2. A'B'
3. C + D + E
4. C'D'E'
5. A'B'C'D'E'

7. Given that F = A'B'+ C'+ D'+ E', which of the following represent the only correct expression for F'?
1. F'= A+B+C+D+E
2. F'= ABCDE
3. F'= AB(C+D+E)
4. F'= AB+C'+D'+E'
5. F'= (A+B)CDE

8. An equivalent representation for the Boolean expression A' + 1 is
1. A
2. A'
3. 1
4. 0

9. Simplification of the Boolean expression AB + ABC + ABCD + ABCDE + ABCDEF yields which of the following results?
2. AB
3. AB + CD + EF
4. A + B + C + D + E + F
5. A + B(C+D(E+F))

1. A * 0 = 0. The dual of any Boolean property may be obtained by interchanging all occurrences of the symbols (*,+,0,1) with the symbols (+,*,1,0). Beware of implicit AND operations (like xy); these ANDs are also converted to +. Therefore, the dual of x + 1 = 1 is: x*0 = 0.

2. 1 or 2
3. A + B + C
4. x(x' + y) = xy
5. Z + XYZ

6. A'B'
7. (A+B)CDE (DeMorgan's theorem twice)
8. 1
9. AB

Tuesday, November 8, 2011

How jQuery works and building Plug-ins

Tranfering data between computers in different locations was started as a military computer science experiment. Today as our technology evolved, data communication become information backbone of our society.
The little boxes we call modems, routers and switches were all born from a need to connect teletype machines together, transferring information started at slow 25 bits per second. At that rate, downloading 1MB might take about 4 days. But we download even full HD movies in real time on ffew hours in on .
ast connections.
An Infographic on the History of the Modem

JQUERY for Advanced Web Designing

Jquery is a Java Script Library to create web apllications using interactive interfaces. Jquery uses AJAX, DOM and CSS

See a Demo of Virtual Panorama

Jquery Quick Learning

Some Excellent jQuery Resources

jQuery Tutorials

1. jQuery Crash Course
2. Getting Started with jQuery
3. Multiple File Upload Magic
4.  jQuery in 15 minutes

5. jQuery for JavaScript programmers
6. Easy Ajax with jQuery
7. jQuery in 15 minutes
8. jQuery Tutorials for Designers
9. Wrapping Images With A Drop Shadow
10. Simplify Ajax development with jQuery
11. Rounded Corners
12. Getting Around The Minimum Height Glitch
21. Safer Contact Forms Without CAPTCHA’s
22. Photo Slider Tutorial
23. Text box hints
24. 5 JavaScript Tricks Made Easy with jQuery
25. JQuery Pop-up Menu Tutorial
26. A Quick Code Igniter and JQuery Ajax Tutorial
27. jQuery and XML revisited
28. What is JSONP?
29. Creating A Sliding Image Puzzle Plug-In
30. Slide out and drawer effect
31. Creating accessible charts using canvas and jQuery
32. jQuery liScroll – a jQuery News Ticker
33. Visual jQuery 1.1

jQuery Plugin Directoies

34. Visual jQuery 1.1
35. Plugins | jQuery Plugins
36. jQueryPlugins.com – The Home Of All jQuery Plugins
37.240 jQuery plugins

jQuery Video Tutorials

38. Jquery Smooth Scrolling Tutorial
39. jQuery AJAX forms Tutorial
40. swfupload ajax jquery drupal module image editor
41. jQuery 1.2.3
42. Drag and Drop JQuery + AJAX
43. jComboBox demo Tutorial

jQery Podcasts

44. Drupal Podcast No. 53: Javascript/JQuery in Drupal | Lullabot
45. Podcast 52: Javascript Libraries :: Boagworld

jQuery ebooks

46. jQuery Reference Guide
47. jQuery in Action

jQuery Cheat Sheets

48. Color Charge jQuery Cheat Sheet (PNG Image, 1313×900 pixels)
49. Charlotte web design jQuery Cheat Sheet (pdf)
50. Jquery Cheat Sheet 1.2. (pdf)

Further Reading

51. 50+ Amazing jQuery Examples
52. 24 ways: Unobtrusively Mapping Microformats with jQuery

Monday, November 7, 2011

A/L ICT Semaster 1 : Term Test Revision

Bits & Bytes

Input Devices
Parts of a Computer

Types of Computers
Storage Devices
Data Information & Knowledge
Basic HTML Tags

Web Desigining

HTML Test 1

HTML Test 2
Number Systems

Logic Gates

Logic Gates

Computer Hardware

Binary Logic
Hardware 2