Introduction to Cyber Security

History of Internet

I don‟t know what the cold war between USA and Russia gave to the world, but defiantly the internet is one of those very useful inventions whose foundation was laid during cold war
days. Russia Launched the world‟s first satellite, SPUTNIK into the space on 4^th October, 1957. This was clearly the victory of Russia over the cyber space and as a counter step, Advanced Research Projects Agency, the research arm of Department of Defence, United States, declared the launch of ARPANET(Advanced Research Projects Agency NETwork) in early 1960‟s. This was an experimental network and was designed to keep the computers connected to the this network to communicate with each other even if any of the node, due to the bomb attack, fails to respond. The first message was sent over the ARPANET, a packing switching network, by Leonard Kleinrock's laboratory at University of California, Los Angeles (UCLA). You will be surprised to know that the fist message that was sent over internet was “LO”. Actually they intended to send work “LOGIN” and only the first two letters reached its destination at second network node at Stanford Research Institute (SRI) and before the last three letters could reach the destination the network was down due to glitch. Soon the error was fixed and the message was resent and it
The major task that ARPANET have to play is to develop rules for communication i.e. protocols for communicating over ARPANET. The ARPANET in particular led to the development of protocols for internetworking, in which multiple separate networks could be joined into a network of networks. It resulted in the development if TCP/IP protocol suite, which specifies the rules for joining and communicating over APRANET.
Soon after, in 1986 NSF(national Science Foundation) backbone was created to and five US universities‟ computing centres were connected to form NSFnet. The participating Universities were:

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  Princeton University -- John von Neumann National Supercomputer Center, JvNC
  
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  Cornell University -- Cornell Theory Center, CTC
  
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  University of Illinois at Urbana-Champaign -- National Center for Supercomputing Applications, NCSA
  
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  Carnegie Mellon University -- Pittsburgh Supercomputer Center, PSC
  
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  General Atomics -- San Diego Supercomputer Center, SDSC
  

NFSnet, the successor of ARPAnet, become popular by 1990 and ARPANET was decommissioned. There were many parallel networks developed by other Universities and other countries like United Kingdom. In 1965, National Physical Laboratory(NPL) proposed a packing switching network. Michigan Educational Research Information Triad formed MERIT network in 1966 which was funded and supported by State of Michigan and the

National Science Foundation (NSF). France also developed a packet swiching network, know as CYCLADES in 1973.
Now there were many parallel systems working on different protocols and the scientist were looking for some common standard so that the networks could be interconnected. In 1978, TCP/IP protocol suits were ready and by 1983, the TCP/IP protocol were apopted by ARPANET.
In 1981, the integration of two large network took place. NFS developed Computer Science Network(CSNET) and was connected to ARPANET using TCP/IP protocol suite. Now the network was not only popular among the research community but the private played also took interest in the network. Initially NFS supported speed of 56 kbit/s. It was upgraded to 1.5 Mbit/s in 1988 to facilitate the growth of network by involving merit network, IBM, MCA and the state of Michigan.
After the copertates took realized the strength and merit of this network, they particepitaqted in the develoement of the network to ripe its benefits. By late 1980s many Internet Service Providers(ISPs) emerged to provide the backbone for carrying the network traffic. By 1991, NFSNET was expended and was upgraded to 45Mbit/s. Many commercial ISPs provided backbone serive and was popular among the corporate. To facilitate the commercial use of the network, NFSNET was decommissioned in 1995 and now the Internet could carry commercial traffic.
Now more and more Universities and research centres throughout the world connected to it. Now this network was very popular amongs the research community and in 1991 National Research and Education Network (NREN) was founded and the World Wide Web was released. Initially the role of internet was only limited to file transfer. The credit of internet what we see it today goes to Tim Berners-Lee who introduced www.With the advent of www, there was a transformation on how the network was used. Now this web of information can be used to retrieve any information available over the internet. Software called, browser was developed to browse the internet. It was developed by researchers at University of Illinois in 1992 and named as Mosaic. This browser enables to browse the internet the way we browse it today.

1. Internet Addresses

With so many devices connected to the internet, we require some mechanism to uniquely identify every device that is connected to the internet. Also we require some centralized
system which takes care of this mechanism so that the signs which are used to identify each device are not duplicate; else the whole purpose is defeated. To take care of this, we have a centralized authority known as Internet Assigned Numbers Authority (IANA), which is responsible for assigning a unique number known as IP(Internet Protocol) address. An IP address is a 32-bit binary number which is divided into four octets and each octet consists of 8 binary digits and these octet are separated by a dot(.). An example of an IP address is

11110110.01011010.10011100.1111100

Each 8-bits in an octet can have two binary values i.e. 0 and 1. Therefore, each octet can have minimum value 0. i.e. 00000000 to maximum value 256 i.e. 11111111 and in total have 2⁸=

256 different combinations.

Again to remember this 32-bit address in binary is bit difficult, so for the better understanding of the human being, it is expressed in a decimal format. But this decimal format is for human understanding only and the computer understands it in binary format only. In decimal, the above IP address is expressed as 123.45.78.125

These octets are used to create and separate different classes. An IP address consists of two parts viz. Network and Host. Network part identifies the network different network and the host part identifies a device of a particular network.
This address uniquely identifies a devices connected to the internet similar to the postal system where we identify any house by fist identifying the county, then state, district, post office, cluster/block and finally the house number. These IP addresses are classified into five categories based on the availability of IP range. These categories/classes are:
Table 1: IP Address Classes