Assignment : FREE AND OPEN SOURCE SOFTWARE

 Answer the Following Questions :-

1. What is open source software?

2. Compare Free software and open source software.

3. Compare OSS and floss.

4. Compare Proprietary software and free software.

5. Compare Free ware and shareware.

6. Compare Freeware and free software

7. Write Short notes on GNU.

8. Write short notes on LINUX.

9. Write Short notes on MOZILLA.

10. Write short notes on APACHE.

11. Write short notes on POSTGRE SQL.

12. Write short notes on PHP.

13. Write short notes on Open Office.

14. What are technological standard and its various categories?

15. Mention some advantages of open standards.

16. What is the significance of Unicode in terms of Indian Language Computing?

17. How phonetic text entry is different from key map based text entry?

18. What is Ogg Vorbis? Why?

19. How to represent character in Memory?

20. What is font and its types?

FREE AND OPEN SOURCE SOFTWARE

FREE AND OPEN SOURCE SOFTWARE

Free Software: It means software is freely accessible, free to use, changed, improved, copied, and distributed without any payments.

Four kinds of freedom

·         Freedom to run the program for any purpose

·         Freedom to redistribute copies.

·         Freedom to study how the program works

·         Freedom to improve the program and release your improvements to the public.

Open Source Software:

Definition: The categories of software / programs whose Licenses do not impose many conditions.

Features:

1. Freedom to run and use the software

2. Modify the program

3. Redistribute copies of either original or modified program (without paying royalties to previous developers).

It can be freely used for modifications, but it does not have to be free of charge. Its source code is available.

Criteria for the distribution of open source software

1. Free distribution

2. Source code

3. Derived works

4. Integrity of the Author’s Source code

5. No discrimination against fields of endeavor.

6. Distribution of License

7. License must not be specific to a product

8. License must not restrict other software

FOSS (free and open software):       

·         Free software- no payments

·         Open source software- for technical progress OSS and FLOSS

·         OSS- Source code is available

(Open source modified and redistributed software) free of cost or with nominal charge.

FLOSS- (free libre and open source software)

FSF (free software foundation)

Founded by Richard Stallman in 1985 to support GNU project.

Non-profit organization created for the purpose of supporting free software movement GNU (free and open source)

Objective: To create a system compatible to UNIX but not identical with it.

Now it offers a wide range of software, including applications apart from operating system.

Proprietary software (neither open nor freely available)

Definition- Its use is regulated and further distribution and modification is either forbidden or requires special permission by the supplier. Source code is not available.

 Freeware

 Free of cost

 Copying and further distribution but not modification.

 Source code is not available

E.g. MS IE

Shareware

 Right to redistribute copies

 After a certain period of time license fee should be paid.

 Source code is not available.

 Modifications are not possible.

 Objective- to increase user’s will to pay for the software. Limits functionality after a trial period of 1-3 months.

Some Software’s

LINUX

 Linux: - free and open source software.

 It can be downloaded from www.linux.org

 Linux is a part of popular web server program LAMP (Linux, apache, MySql, PHP).

Mozilla

 Freeware

 No source code available

 free internet software

It can be downloaded from www.mozilla.org

Apache Server

 The most common web server (or HTTP server) software on the Internet.

 Apache is designed as a set of modules, enabling administrators to choose which features they wish to use and making it easy to add features to meet specific needs including handling protocols other than the web-standard HTTP.

 Apache HTTP server is an open source web server.

 It is component of LAMP.

Denial-of-services attacks:

DoS are those attacks that prevent the legal users of System from accessing or using the resources, information or capabilities of the system. It may be of following types:

·         Denial of Access to Information: Such attacks cause deletion or changing of important information to non readable format.

·         Denial of Access to Applications: Such attacks make the applications unusable or unavailable for legal user of the system.

·         Denial of Access to Communications: Such attacks includes cutting of communication wire, jamming radio communications, flooding a system with junk mail.

Threats to network security: It may be of following types:

a.       Snooping: It refers to unauthorized access to someone else’s data, email or computer activity.

b.       Eavesdropping: It refers to unauthorized listening / intercepting someone else’s private communication / data/ information.

Standards: Standards refers to an established set of rules or requirements which are approved by recognized body or widely used across various software platforms. For ex.: PDF (Portable documents format) is a technical standard widely used by the industry.

They are of two types: Proprietary Standards and Open Standards.

Proprietary standards are those for which users have to buy license to use them.

For e.g. MS Office format .doc, .ppt, .xls etc

Open Standards are internationally accepted technical standards that guarantee that data can be exchanged across platforms and for any applications. Open is feely open to all.

Advantages of Open Standards:

i.                     Making the data accessible to all.

ii.                   It ensures data is application and platform independence.

iii.                  Diversity and Interoperability in the Industry i.e. it enables business and people to go for any technology of their choice as per their needs and budget.

E.g.: ASCII Characters, HTML file, Joint Photographic Expert Group, Portable Network Graphic etc.

Ogg Vorbis:

 It is a new audio compression which is open format developed by Xiph.org. It is roughly comparable to mp3, mpeg-4 formats and is completely free, open and unpatented. Hence it imposes no restrictions on its usage, types of usage, distributions, redistribution etc.

Indian Language Computing:

 Indian Language computing refers to ability to interact in diverse Indian language on electronic system.

How to represent character in Memory?

ASCII:

 American Standard Code for Information Interchange is widely used alphanumeric code in most microcomputers and minicomputers and in many mainframes. It is 7 bit code hence it can represent standard 2⁷=128 characters.

ISCII:

 Indian Standard Code for Information Interchange (ISCII) is an eight bit code capable of coding 256 characters. It retains all ASCII characters and also offers coding for Indian Scripts. Thus it is also called as Indian Script code for Information Interchange.

Transliteration:

 When we type Indian Language words phonetically in English script and tool will automatically convert them into corresponding language words called as transliteration.

Unicode:

Unicode provides a unique number for every character, no matter what the platforms, no matter what the program, no matter what the language. Unicode can represent 94140 characters. Unicode standard has incorporated Indian Scripts under the group named Asian scripts. Indian scripts included as Devnagari, Bengali, Gurumukhi, Gujarati, Oriya, Tamil, Telugu, Kannada, and Malayalam.

Fonts:

 A Font refers to a set of displayable text characters called glyphs, having specific style and size. There are two categories of font: True Type Font and Open Type Font.

 True Type Font: It is developed by Apple and licensed to Microsoft. It is 8 bit font which is compatible with Microsoft Windows and MAC OS.

Open Type Font: It is the extension of the True Type Font Format which is 16 bits font and support 65536 characters (Unicode characters).

Indian Language Text Entry:

 Many Tools / software have been developed to facilitate the typing of Indian Language text.

There are two types text entries:

i.                     Phonetic Text Entry: Words typed as per their pronunciation in English script and later on converted to Corresponding (Hindi/Gujarati) language work is known as phonetic text entry.  

ii.                   Key map based text entry: When you type text from a keyboard having key mapping of Indian language characters, is known as key map based text entry.

Computer Networking Assignments for class XII ( Summer Vacation)

1. What is a computer network? What are its advantages?

2. What is meant be communication channels? Give two examples of guided media and two examples of unguided media.

3. Which communication channel(s) is/are suitable in each of the following situations?

a. Setting up a LAN

b. Transfer of data from a laptop to a mobile phone.

c. Transfer of data from one mobile phone to another.

d. Creating a remote control that can control multiple devices in a home.

e. Very fast communication between two offices in two different countries.

f. Communication in a hilly area

g. Communication within a city and its vicinity where cost of cabling is too high.

4. Why is a switch called an intelligent hub?

5. When is a repeater used in a computer network?

6. Diagrammatically show how you would connect 6 PCs, 1 server, 1 printer, and 2 scanners in

 a. Star topology b. Bus topology

7. Two engineers in the same room have connected their Palm-tops using bluetooth for working on a Group presentation. Out of the following, what kind of Network have they formed? LAN, MAN, PAN, WAN

8. What is a MAC address? What is the difference between a MAC address and an IP address?

9. Give some examples of domain names and URLs. How is a domain name different from a URL?

10. What is domain name resolution?

11. Define Network security? What kind of attacks can be made on data and computer networks?

12. List some methods which are used for network security.

13. Differentiate (with examples wherever possible) between :

a. LAN and MAN                    b. MAN and WAN

c. Hub and Switch                  d. Guided and Unguided media

14. Write one advantage of star topology over bus topology and one advantage of bus topology over star topology.

15. Ishika Industries has set up its new production unit and sales office at Ranchi. The company compound has 4 buildings as shown in the diagram below:

Buidling

Distance

No. of Computer

1. Suggest a cable layout of connections between the buildings so that each building is directly connected to Administrative Office.

2. Suggest the most suitable place (i.e. building) to house the server of this production unit with a suitable reason.

3. Suggest the placement of the following devices with justification:

(i) Repeater                 (ii) Hub/Switch

4. The Administrative office of this unit is to be linked with the head office situated in

Patiala (Punjab). What will be the most economical way to do this? Justify your answer.

Computer Networking

Computer Networking

A computer network is a collection of interconnected computers and other devices which are able to communicate with each other. In this context, the term interconnected means that there exists a path through which data can be transmitted from one computer/device to another.

A few of these advantages are:

• Resource Sharing
• Cost saving
• Collaborative user interaction
• Time saving
• Increased storage

Wired Technologies

Co-axial Cable:

Coaxial cable conducts electrical signal using an inner conductor (usually a flexible solid or stranded copper wire) surrounded by an insulating layer and all enclosed by a shield layer, typically a woven metallic braid; the cable is often protected by an outer insulating jacket. Normally, the shield is kept at ground potential and a voltage is applied to the center conductor to carry electrical signals. The advantage of coaxial design is that the electric and magnetic fields are confined to the dielectric with little leakage outside the shield. On the converse, electric and magnetic fields outside the cable are largely kept from causing interference to signals inside the cable.

Ethernet Cable:

An Ethernet crossover cable is a type of Ethernet cable used to connect computing devices together directly. Normal straight through or patch cables were used to connect from a host network interface controller (a computer or similar device) to a network switch, hub or router. A cable with connections that "cross over" was used to connect two devices of the same type: two hosts or two switches to each other.

Optical Fiber:

An optical fiber (or optical fibre) is a flexible, transparent fiber made of a pure glass (silica) not much thicker than a human hair. It functions as awaveguide, or “light pipe”[1], to transmit light between the two ends of the fiber.[2] The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces. Specially-designed fibers are used for a variety of other applications, including sensorsand fiber lasers.

Wireless Technologies

Bluetooth:

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances (using short-wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security.

Infrared:

Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74micrometres (µm), and extending conventionally to 300 µm. These wavelengths correspond to a frequency range of approximately 1 to 400 THz,[1] and include most of the thermal radiation emitted by objects near room temperature. Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.

Microwave:

Microwaves are radio waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.[1] This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries.[2] In all cases, microwave includes the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm).

Radio Waves:

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometer. Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight.

Satellite:

A satellite link is a communications subsystem that involves a link between a transmitting Earth station and a receiving Earth station via a communications satellite.

Network Topologies

When we have to connect computers/devices in a network, there may be certain conditions which have to be satisfied. Depending upon these conditions, there may be different ways of interconnecting the computers/devices. The way in which the computers/devices are physically interconnected to form a network is called a Topology.

Bus Topology

In bus topology all the nodes are connected to a main cable called backbone. If any node has to send some information to any other node, it sends the signal to the backbone. The signal travels through the entire length of the backbone and is received by the node for which it is intended. A small device called terminator is attached at each end of the backbone. When the signal reaches the end of backbone, it is absorbed by the terminator and the backbone gets free to carry another signal. This prevents the reflection of signal back on the cable and hence eliminates the chances of signal interference.

Characteristics of Bus topology

• It is easy to install.
• It requires less cable length and hence it is cost effective.
• Failure of a node does not affect the network.
• In case of cable (backbone) or terminator fault, the entire network breaks down.
• Fault diagnosis is difficult.
• At a time only one node can transmit data

Star Topology

In star topology each node is directly connected to a hub/switch (zoomed or blinking). If any node has to send some information to any other node, it sends the signal to the hub/switch This signal is then broadcast (in case of a hub) to all the nodes but is accepted by the intended node(s). In the case of a switch the signal is sent only to the intended node(s). Star topology generally requires more cable than bus topology.

Characteristics of Star topology:

• It is more efficient topology as compared to bus topology.
• It is easy to install
• It is easy to diagnose the fault in Star topology.
• It is easy to expand depending on the specifications of central hub/switch
• Failure of hub/switch leads to failure of entire network
• It requires more cable length as compared to bus topology

Tree Topology

Tree topology is a combination of bus and star topologies. It is used to combine multiple star topology networks. All the stars are connected together like a bus. This bus-star hybrid approach supports future expandability of the network.

Characteristics of Tree topology:

• It offers easy way of network expansion
• Even if one network (star) fails, the other networks remain connected and working.

Mac Address:

A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number and may be referred to as the burned-in address. It may also be known as an Ethernet hardware address (EHA), hardware address or physical address. A network node may have multiple NICs and will then have one unique MAC address per NIC.

IP Address

An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."

Domain Name:

A domain name is an identification string that defines a realm of administrative autonomy, authority, or control on the Internet. Domain names are formed by the rules and procedures of the Domain Name System (DNS).

Domain names are used in various networking contexts and application-specific naming and addressing purposes. In general, a domain name represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet.

Types of Networks

LAN

A local area network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.

ARCNET, Token Ring and other technology standards have been used in the past, but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently used to build LANs.

MAN

A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet.

WAN

A Wide Area Network (WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.

PAN
A personal area network (PAN) is a computer network used for communication among computerized devices, including telephones and personal digital assistants. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink). A wireless personal area network (WPAN) is a PAN carried over wireless network technologies such as IrDA, Bluetooth,Wireless USB, Z-Wave, ZigBee, or even Body Area Network. The reach of a WPAN varies from a few centimeters to a few meters. A PAN may also be carried over wired computer buses such as USB and FireWire.

Network Devices

HUB:
An Ethernet hub or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer (layer 1) of the OSI model. The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.

Switch

A network switch or switching hub is a computer networking device that connects network segments or network devices. The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (layer 3) and above are often referred to as layer-3 switches or multilayer switches.

Repeater:

A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.

Gateway:

A gateway is a network point that acts as an entrance to another network. On the Internet, a node or stopping point node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes, while the nodes that connect the networks in between are gateways. For example, the computers that control traffic between company networks or the computers used by internet service providers (ISPs) to connect users to the internet are gateway nodes.

Network Security

Denial of Services

A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DoS attack) is an attempt to make a computer or network resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person, or multiple people to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely.

Intrusion Problem

Snooping, in a security context, is unauthorized access to another person's or company's data. The practice is similar to eavesdropping but is not necessarily limited to gaining access to data during its transmission. Snooping can include casual observance of an e-mail that appears on another's computer screen or watching what someone else is typing. More sophisticated snooping uses software programs to remotely monitor activity on a computer.