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History and sources Internet.

The history the Internet rotates round four different aspects.

On the first place should be delivered technological evolution which began with early researches on package switching, the ARPANET network and on related issues. The modern researches continue to expand the infrastructure horizons directly in several directions, including scaling, increase of efficiency and high level functionality.

The second aspect is maintenance and control of global, difficult infrastructure.

The third it is possible to call the social aspect which has led to formation of wide community of «Internet surfers», jointly working over creation and technology development.

The fourth it is possible to select with aspect the aspect of the commercialization which is showing in extremely effective transformation of results of researches in everywhere unrolled, widely available information infrastructure what the Internet today is.

Original prototype of the Internet often designate National (and also Global, or Galactic) Information Infrastructure. The history of the Internet is complicated, it includes many aspects, and in general, – technological, organizational and social aspects.

Influence of the Internet extends not only on technological area of computer communications; it penetrates all society as more and more wide circulation is received by operational means of electronic commerce, knowledge acquisition and making of public actions.

 

Theoretical bases of the Internet.

Actually, the Internet consists of a set of the local and wide area networks belonging to the different companies and the enterprises, working according to the most various protocols, connected among themselves the different communication lines, physically transferring data on telephone wires, an optical fiber, via satellites and radio modems.

The structure the Internet reminds a web in which nodes there are the computers connected among themselves by communication lines. The nodes the Internet connected by high-speed lines of communication, make base the Internet.

Each computer on the Internet has the unique address. In the TCP/IP protocol each computer is addressed by four points separated from each other decimal numbers, each of which can matter from 1 to 255. The address of the computer looks as follows: 19.226.192.108

Such address is called as the IP address. Such addressing of computers on a network allows to connect to it at most 4 294 967 296 computers. It is possible to read that the IP address of the computer is analog of telephone number of the subscriber. When any large regional network is connected to Internet, ISOC selects for this network corresponding to its possible scales and needs the range of IP numbers.

There are two methods of separation of the IP address:

1) Dynamic (temporal) separation when the IP address is selected to the computer only for the period of a communication session with Internet, the address can change from one connection to another



2) Continuous fixing of the IP address at the computer

The computer to which the constant or dynamic IP address is selected is called as the host-computer, or as head, leading, and principal.

It is inconvenient to user to remember such addresses which besides can change. Therefore on the Internet there is a Domain Naming service (DNS – Domain Name System) which allows calling each computer by name. On a network there are million computers and that names didn't repeat, they are partitioned on independent domains.

Thus, the address of the computer looks as some domains separated by a point: <n segment=««>. … <segment 3=««>. <segment 2=««>. <segment 1=««>.

Here a segment 1 – the domain of 1 level, a segment 2 – the domain 2 levels etc.

The domain name is a unique name which this service provider elected to itself for identification, for example: ic.vrn.ru or yahoo.com

For example, the domain address (domain name) www.microsoft.com designates the computer with the name www in the domain microsoft.com. Microsoft is a company name; com is a domain of the commercial organizations. The computer name of www says that on this computer there is a WWW service. It is a standard type of the address of servers of major companies (for example, www.intel.com, www.amd.com etc.). Names of computers in different domains can repeat. Besides, one computer on a network can have some DNS names.</segment></segment></segment></n>

The domain of 1 level normally defines the country of location of the server (ru – Russia; ua – Ukraine; uk – Great Britain; de – Germany) or a type of the organization (com – the commercial organizations; edu– the scientific and educational organizations; gov – government agencies; org – non-profit organizations).

In the Internet simply domain names and the universal pointers of the URL resources (Universal Resource Locator) are used not.

URL includes:

• The access method to a resource, i.e. the access protocol (http, gopher, WAIS, ftp, file, telnet, etc.);

• Network address of a resource (host-machine and domain name);

• A full path to the file on the server.

In a general view the URL format looks so:

method://host.domain [:p]/path/filename, where method – one of the values listed below:

file – the file on local system; http – the file on World Wide Web the server; gopher – the file on Gopher the server; wais – the file on WAIS (Wide Area Information Server) the server; news – news group of a teleconference of Usenet; telnet – an output on Telnet network resources; ftp – the file on FTP – the server; host.domain – domain name on the Internet; port – number which it is necessary to specify if the method requires port number.

The protocol is a set of agreements which defines a data interchange between different programs. Protocols set message passing and error handling methods on a network, and also allow developing the standards which have not been bound to a specific hardware platform.

Network protocols order operation rules to computers which are connected to a network. They are built by a multi-level principle. The protocol of some level defines one of technical rules of communication. Now for network protocols the OSI model is used.

The OSI-model is a seven layer logical model of operation of a network. The OSI model is implemented by group of protocols and the rules of communication organized in some levels.

At the physical layer are defined physical (mechanical, electrical, optical) characteristics of communication lines.

At the data link layer rules of use of the physical layer are defined by network nodes.

The network layer is responsible for addressing and delivery of messages.

The transport layer supervises sequence of passing of components of the message.

The task of session level – communication coordination between two application programs working at different workstations.

The presentation layer serves for data transformation from an internal format of the computer in a transmission format. The application layer is boundary between the application program and other levels.

The application layer provides the convenient interface of communication of network programs of the user.

The TCP/IP protocol is the two lower layer protocols being a basis of communication on the Internet. The TCP protocol (Transmission Control Protocol) breaks handed-over information for the portions and numbers all portions. By means of the IP protocol (Internet Protocol) all parts are transferred to the receiver. Further by means of the TCP protocol it is checked, whether everything parts are received. When receiving all portions of TCP locates them in the necessary order and collects in a whole.

Internet services.

World Wide Web: normally called WWW (from World Wide Web) or a web represents a set of specially created pages viewed in a web browser. A web browser – the program application, allowing to define a location and to display the web pages including the text, a graphics and other multimedia contents, for example, music.

E-mail: or an e-mail, it is available on all Internet. It gives the chance to people to send quickly files worldwide. It can be simply text notice or can include a graphics or any other contents.

File transfer: moves or copies files from one computer on another. There are specific leading principles, or protocols which control data transfer on the Internet, known as the file transfer protocol (File Trransfer Protocol, FTP).

News of Usenet (Usenet News): a network of computers which exchange articles on certain subjects, provide support to software products or offer responses to different categories of questions.

News groups (newsgroups): network conference in USENET, organized for guiding of discussions and an exchange of news. Reading and sending of messages are carried out by the program being launched on the computer of the user and incorporating to the server of news.

Information security and its components.

Information security is understood as security of an information system from the accidental or premeditated interference, causing damage to owners or users of information.

In practice by the major three aspects of information security are:

• Accessibility (possibility for reasonable time to receive required information service);

• Integrity (an urgency and consistency of information, its security from corrupting and unauthorized change)

• Confidentiality (protection against illegal access to information).

Formation of a mode of information security – a problem complex. Measures for its decision can be subdivided into five levels:

1. Legislative (laws, regulations, standards, etc.);

2. Moral and ethical (the various standards of behavior, which non-compliance carries to falling of prestige of the specific person or the whole organization);

3. Administrative (the actions of the general character undertaken by a manual of the organization);

4. Physical (mechanical, electro - and electronic and mechanical hindrances on possible ways of penetration of potential violators);

5. Hardware-software (electronic devices and special programs of protection of information).

Uniform set of all these measures directed on counteraction to security risks for the purpose of minimizing of possibility of a damage, will form protection system.

Security risks of information and their classification.

The knowledge of possible threats, and also weak spots of the protection, which these threats normally exploit, it is necessary to select the most economic security protections.

Threat is a potential possibility definitely to break information security.

Attempt of implementation of threat is called as attack, and the one who makes such attempt, – the malefactor. Potential malefactors are called as threat sources.

More often threat is a consequence of existence of weak spots in protection of information systems (such, for example, as possibility of access of outside persons to the crucial equipment or errors in the software).

Threats can be classified by several criteria:

• On aspect of information security (accessibility, integrity, confidentiality) against which threats are directed first of all;

• On components of information systems, at which threats are aimed (data, programs, the equipment, supporting infrastructure);

• On an implementation method (accidental/premeditated actions of natural/technogenic character);

• On layout of a source of threats (in/out of the considered IC).

And the most dangerous (from the point of view of the size of a damage) inadvertent errors of standard users, operators, system administrators and other persons servicing information systems are the most frequent.

Sometimes such errors also are actually threats (incorrectly entered data or the program error which has caused crash of system), sometimes they create weak spots which malefactors (are that normally administration errors) can use. According to some information, to 65 % of losses – a consequence of inadvertent errors.

Fires and floods don't bring so many troubles, how many illiteracy and negligence in operation. Obviously, the most radical method of fight against inadvertent errors – the maximum automation and strict monitoring.

Other threats of accessibility are classified on components of an information system at which threats are aimed:

• Failure of users;

• Internal failure of an information system;

• A failure of supporting infrastructure.

It is possible to carry systems in supporting infrastructure electro - water - and heat supplies, air conditioners, means of communications and, of course, the service personnel.

Normally with reference to users the following threats are considered:

• Unwillingness to work with an information system (is shown to master if necessary new possibilities and in case of a discrepancy between requests of users both the actual possibilities and technical characteristics more often);

• Impossibility to work with system owing to absence of the appropriate preparation (a lack of the general computer literacy, failing to interpret diagnostic messages, failing to work with documentation, etc.);

The main sources of internal failures are:

• Retreat (accidental or deliberate) from the set service regulations;

• A system output from a standard mode of maintenance owing to accidental or premeditated actions of users or the service personnel (exceeding of estimated number of requests, excessive volume of processed information, etc.);

• Errors in case of (pen) system configuring;

• Failures program and hardware;

• Corrupting of data;

• Corrupting or equipment damage.

In relation to supporting infrastructure it is recommended to consider the following threats:

• Operation violation (accidental or deliberate) communication systems, power supply, water - and/or heat supplies, conditioning;

• Corrupting or damage of locations;

• Impossibility or unwillingness of the service personnel and/or users to execute the duties (civil disorders, failures on transport, an act of terrorism or its threat, a strike, etc.).

The so-called «offended» employees – present and former are very dangerous. As a rule, they aim to harm to the organization - to «offender», for example:

• To spoil the equipment;

• To build in a logical bomb this will destroy over time programs and/or data;

• To delete data.

The offended employees who even were are familiar with orders in the organization and are capable to cause a considerable damage. It is necessary to track that in case of dismissal of the employee of his right of access (logical and physical) to information resources voided.

Are dangerous, certainly, and natural disasters – fires, floods, earthquakes, hurricanes. According to the statistics, and to volume of similar «malefactors» (among which most dangerous – power supply interruption) is the share of a share of fire, water of 13 % of the losses put to information systems.

 

Archivers.

Archiving is a compression, multiplexing, information package for the purpose of its more rational placement on the external carrier (a disk or a diskette). Archives are the programs implementing an archiving process, allowing creating and unpacking archives.

Need of archiving is connected to information backup on disks and diskettes for the purpose of saving of the software of the computer and protection it from damage and destruction (deliberate, accidental or under the influence of a computer virus). To reduce information losses, it is necessary to have backup copies of all programs and files.

Programs packers (archives) allow to create copies of files of the smaller size at the expense of ad hoc methods of compression of information and to integrate copies of several files in one archive file. It gives the chance on disks or diskettes to place more information, which is to increase density of information storage per carrier unit of volume (a diskette or a disk).

Besides, archive files are widely used for information transfer on the Internet and by e-mail, and thanks to compression of information speed of its transmission raises. It is especially important if to consider that high-speed performance of the modem and communication link (telephone line) is much less, than the processor and a hard drive.

For creation and unpacking of archive it is used the following methods:

1) The method of operation of the archiver in command line – is most the general method of control over the archiver by means of introduction of commands in command line.

2) Method of use of archived properties of shell programs (Norton Commander, DOS Navigator, Windows Commander, etc.). This method is most perspective, as shell programs allow to automate an archiving process and by that sharply to facilitate and simplify it.

3) Use of «browsers» of ARCVIEW and AVIEW for unpacking of archives. This method is rarely used. It is auxiliary.

 


Date: 2015-12-24; view: 124


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