What is Networking?

In simple word, networking can mean a chain or loop formed to connect or share. However, technologically, networking refers to the collection of hardware devices connected via hardware/software for the purpose of sharing and exchanging information. The connectivity could either be logically or physically.

Advantages of Networking:

The most important advantage of networking is to connect and to share. Some other advantages are described as follows:

 1) Networking can connect two devices which are placed side by side as well as two devices which placed are across the globe. The connectivity parameter of distance can be overcome by choosing the type and size of network as LAN, WAN etc.

2) With Networking, data can be easily shared and transferred across the globe. One of the best examples of exchanging information via networking is the Internet which can be accessed globally by anyone.

3) Networking can also reduce the expenditure of having hardware devices as printer, scanner for each system. Instead, the interconnected system can use a single printer/scanner to get printout/scan from any of the system’s command. This is really cost effective from organization point of view.

4) Networking also manages data security within the organisation. Instead of spreading a particular data to each and every individual in an organization, the data can be placed in a shared folder/application where the employees of the organization will have access to. This enhances the security of the data and ensures that important and critical information is conveyed to everyone.

5) Internet is one of the best examples of networking. For illustration purpose, suppose in an organization if 50 employees are given access to individual internet connections which run on a very slow speed. Instead, the employer can opt for a high speed connection and share it among his employees. This would enhance the performance of overall organization.

Disadvantages of Networking:

1) Although networking has many advantages, it is a real concern when cost comes into picture. The set up required to connect various systems/devices is a really expensive affair. Hence, cost effectiveness matters when you want to connect few numbers of devices.

2) For the networking to take place effectively, a trained professional should be hired, who can manage and maintain the whole network effectively. Also, troubleshooting skills are required in case of any problem occurs in any particular system. Thus, either a trained IT professional or a team of professionals (in case of large companies) is required to run it smoothly.

3) Although you can share/transfer data via a common folder/application, it becomes really troublesome when you want to share particular data only among a particular group/individual. This arise some of the security concerns for a poorly secured network.

Some basic terms used in Networking:

Protocol: Protocol basically refers to a set of rules or a code of conduct that has to be followed. In Networking, they define a language as well as procedure that allows systems/devices to communicate.

Packets: These are chunks of data/messages sent over a network.

Datagram: Same as packets but refer to network layer technologies sent at a higher level of the OSI reference model.

Frame: Same as packets but refer to network layer technologies sent at a lower level of the OSI reference model.

Cell: Packets and frame are variable in size. The messages in a cell are fixed in size.

Segments: TCP (Transmission Control Panel) calls its messages segments.

Protocol data Unit (PDU) and Service data Unit (SDU) - Formal OSI terms for messages. In PDU, message is handled by a particular protocol whereas SDU is the data in the payload.

Message Elements: The packets/messages generally have 3 elements:

Header: This is the control link between protocol elements on various devices. It helps in the communication and is placed before the actual data.

Data: Also termed as the payload. It contains the actual data that needs to be transmitted.

Footer: This is optional or not present in most of the messages. It is placed after the data.

Addressing and Transmitting of Messages:

Having an address on the message helps the system to know where the actual message would go and transmitting help it in sending to it to the rightful recipient.

Unicast Message Transmission: It is intended to be sent from one particular device to another specific one. No other system should interfere in between.

Unicast Addressing: In this, the message is addressed to a specific recipient.

Broadcast Message Transmission: In this, the message is sent to all the devices in the network.

Broadcast Addressing: For a particular purpose, the addressing is done via special addresses.

Multicast Message Transmission: Sent to a particular group that meets a specific set of criteria.

Multicast Addressing: It identifies a specific device for which the message is to be received.

Anycast Messaging: Identifies a message that should be sent to the closest member of the group.

 OSI Reference Model

OSI (Open System Interconnect) reference model is developed by ISO (International Standards Organization). It defines the communication process on how a data from an application on a particular computer can be transferred to an application on another computer.

The first four (upper layer) layers are used whenever a message passes from or to a user.

The last three (lower layer) layers are used when any message passes through the host computer.

Switching Network:

Circuit Switching Network: A connection as that of a circuit is being set up and only one path is being followed to have communication between two particular devices.

Packet Switching Network: In this the data is being sent as packets via various paths. No particular path is being followed. At the destination device, the data is read from the packet and reassembled.

The only disadvantage of packet switching is that the data might be lost on the way and may be put up in the incorrect order.

Two basic types of protocol

Connection Oriented Protocols: In this type, before transferring data, a logical connection is being set up between the two devices. After the transfer is completed, the connection is broken. It is required in high layer protocol.

E.g. TCP (Transmission Control Protocol)

Connectionless Protocol: This type does not require any connection. For sending packets (low layer data sending) connection is not required.

e.g.: UDP (User Datagram Protocol)

Approaches for setting up a network:

Point to point network: Networking between two particular devices where message addressing is not required.

Peer to peer networking: Peer means equal. In this type of networking, the resources/data are shared by each and every machine in the network. This is very simple and cost effective networking.

Client/Server Networking: Client refers to the smaller individual PC. Server refers to the powerful computers with huge memory and storage space. They have fast network connection.

 The centralized servers provide services to a large number of clients/ user machines. It is used for large networks. Advantages are good performance, security, reliability, centralized resource servicing. Disadvantages are that it is complicated and expensive.

A resource should be protected in both ways - externally and internally. Internal harms include unauthorized access, transfer of data and changing or destroying some important piece of information. Stress is mostly given to internal security of software and data. But for a system to be 100% secure, external security is also equally important. External security provides different ensuring ways to secure both computing system and its data from outside attacks of the system. Threats may be physical damage, non-technical threats or operational system faults. Let me explain some of the common external threats and how they can be overcame.

Physical security:
Even if the system is internally secured, it should be kept away from external damages or stealing. i.e. A system should be physically secure and its parts should never be damaged or removed without the consent of its owner. The whole internal security measures go futile, if the system is not kept protected against external theft or physical damage.

Non-technical threats:
A common technique involved in this type of threat is social engineering, which is more harmful even than the internal security threats. Here, the persons who are involved with secure data can be brainwashed and given promises of money or good offers and prompt them to reveal important information about that firm. By this way, important passwords, access codes and even security measures can be cracked.

Operational security:
Some of the precautions should be done to secure the most important piece of information. It include backups and auditing. Always keep a copy of important piece of information,somewhere away from the system. If so, even if the system is damaged by a natural calamity,fire, disk failure, system error and even if the system is stolen or damaged by intruders,important information can be recovered. But, one should take care about backups of important piece of information. Such backups should be protected from unauthorized access by providing some access code or passwords. Another method is auditing. Periodically, internal data has to be checked, verified and recorded to find whether the system security is breached and this process contains an audit record known as audit log. i.e. Accurate records are keptand each entry in the log should record the name of the user or user_id who initiated a particular operation in the system, with the login time and his motive.

Cryptography for computer security
Cryptography is the process of encoding an important information before sending and later decoded by the trusted user or associate. The word is derived from a Greek word meaning 'secret writing'. Cryptography has been used from ancient period itself which purposefully helped a sender to send some piece of information in a hidden format. Since the message is changed according to certain pre-determined code, only the person who knows it can decode it and hence it would be a useless message if it is accidently handed over to a stranger or enemy.

 

Thus cryptography helps to communicate information secretly. Cryptography has been termed as 'modern cryptography' and has been developed for computer-based uses before 50 years which gives us certain unbreakable encoding systems.
Let 'Msg' be the message with a sequence of bits. 'Msg' is called plain text which can be read and is not changed yet. Let 'EF' be the encryption function which takes the message and an encryption key E_key which produces an encrypted message CT, called the cipher text.
Ef( Msg, E_key ) = CT
Df, the decryption function reverses the process using D_key, the decryption key.
Df( CT, D_key ) = Msg
i.e. The encrypted message is decrypted to get the original message.
Very often, encryption and decryption functions are same. Also, both the keys are either same or very closely related. Such a system is called a private key cryptosystem where both the keys are kept private due to security reasons. If only one of them is kept secret, then it is termed as public key cryptosystem. Best example is installation codes of certain software, which is provided along with the CD, which may be often very lengthy and contains both alphabets and numbers.
Often cryptography is used for privacy or keeping data private. It helps the user to keep files in the system, thus preventing anyone else to read. It is most applicable in the case of networks, where data can be transferred from one system to another easily. Often cryptography helps in system authentication based on the principle of digital signature. All the bits in the document are made related to one another. Thus we can't change just one or two of those bits. Bits of the message undergo encryption which mixes all of them in different complicated ways. Even, crypography is used for authenticating public keys.

 

Computer security in a matter of concern for all of us. If we are not alert we may be attacked by malicious hackers, trojans, worms, rootkits, keyloggers, malware, etc. These threats may affect our computer through internet, CDs, pen drives and other secondary storage devices. These threats may wreck our computer partially or may cause a total destruction.

Antivirus softwares are the solution to these threats. There are many good antivirus software out in the market. But many people don’t know that any antivirus software cannot render a computer fully virus proof. Antivirus software also uses lots of resources like RAM, hard disk space, etc. We must use antivirus software to get rid of these threats and these antivirus software must be updated daily on the internet to reap their benefits and stay safe but what if a person has no internet connection at home? What if a person does not want to spend money on antivirus software? What does a person do then? Well, there are free antivirus software and although they work they are not as good as their paid counterparts and do not provide total security.

The trojans, rootkits, worms, etc. all affect the Microsoft Windows platform. The Windows Operating sytems are vulnerable to these kind of threats. There is another safer alternative to Windows Operating system. Ubuntu. Ubuntu is an operating system based on the Linux kernel. Ubuntu is free software unlike Windows, is not affected by the above-mentioned threats. Ubuntu does not need antivirus software and so is a better alternative to Windows platform. Still, a user has to take the necessary precautions on the internet to be safe.

Some precautions to be taken are –
1.    Never click links sent to you in mail. Copy-paste or type it in the address bar of your browser.
2.    Don’t click ads on free stuff. Most free games, songs, etc contain viruses.
3.    Even if you don’t want to buy antivirus software, use free antivirus software.
4.    If you don’t have an internet connection, go to a internet café and update your antivirus software at least monthly.
5.    Use rootkit detection software, malware detection software to check for rootkits or malware.
6.    No website is going to ask for your id and password because of technical error. So go to that website directly and try to login, if you can’t do that, contact the websites admin.

This is my first article, so if I’ve made mistakes, or you have some suggestion, please let me know.

                                       For most of the browsers this is a very frustating situation when your web browser redirects you to a different page which in no way relates to what you have searched for.Of lately, google redirect viruses have become a severe problem with web browsers. This is mainly either http://95p.com or http://mediashifting.com (there might be some other web browser hijacker too). The redirect malware not only infects your browser and system but it also puts your system information security at risk. These malwares are not easily detected by the antiviruses. As a result proper care should be taken to get rid of this malicious trojan.

Some of the troubleshooting that is required to remove this disastrous malware are:

 

1)The associated files of google redirect malwares should be found and deleted. Check Windows HOSTS file. For this go to:

 

a)C:\WINDOWS\system32\drivers\etc.

b) Double-click "hosts" file to open it. Choose to open with Notepad.There should be only one line: 127.0.0.1 local host in Windows XP and 127.0.0.1 local host::1 in Windows Vista. If there are more, then remove them and save changes.

2) Stop google redirect malwares process using the windows task manager.

a) Press CTRL+ALT+DELETE to open the Windows Task Manager.

b) Click on the "Processes" tab, search for the virus random .exe, then right-click it and select "End Process" key.

3) Uninstall google redirect malwares program from windows control panel Add/Remove Programs.

4) Check Local Area Network (LAN) settings.

a)Open Internet Explorer. In Internet Explorer go to: Tools->Internet Options.

b) Click on "Connections" tab, then click "LAN settings" button.

c) Uncheck the checkbox under "Proxy server" option and click OK.

5) Make sure that DNS settings are not changed.

a)Open Control Panel (Start->Control Panel).

b) Double-click "Network Connections" icon to open it.

c) Right click on "Local Area Connection" icon and select "Properties" Choose "Obtain DNS server address automatically" and click OK.

6) Remove unknown or suspicious add-ons from internet explorer.

a)In Internet Explorer go to: Tools->Manage Add-ons.

b)Disable suspicious Toolbars or Search Providers.

7)The registry entries of google redirect malwares program need to be removed.

a)Click "Start" button and selecting "Run." type "regedit" into the box and click "OK."

b)Once the Registry Editor is open, , find and remove all google redirect malwares program registry files. For example:

8) Reset a Router Back to the Factory Default Setting.

a)Go to Start >Run (or WinKey+R) and type in "cmd" .

b) In the new window type "ipconfig /flushdns" and hit Enter.

9) For automatic removal, go for the following softwares :

http://www.superantispyware.com/ :it detects and remove spyware, adware, trojan horses, rogue security software, computer worms,rootkits, parasites and other potentially harmful software applications.

http://www.malwarebytes.org/: removes all forms of malware, including viruses, Trojans, spyware, adware and rootkits.

http://kaspersky-tdsskiller.en.softonic.com/: It detects and removes Tidserv, TDSServ and Alureon rootkits and alsomalicious Trojans.TDSSKiller tool removes malware belonging to the family of Rootkit.Win32.TDSS. (It is the best advised for removing the redirect trojan)

http://www.combofix.org/download.php: It scans your computer for known malware, and when found, attempts to clean these infections automatically.