Computers and Software 5

In the process of graduate design were investigated 15 packages subscriber software. In the subscriber software packages examined their capabilities in the operating environment MS-DOS and MS-Windows, methods for setting modes, as well as ease of operation. According to the results of studies for each package subscriber software were advised of the possibility of the use of a package in the global information network operating on the basis of protocol TCP \ IP.

For comparison, subscription software packages each other and selecting the best program was written by an expert of choice. Based on the research the following conclusions.

For operating MS-DOS, the best package of subscription software from a user perspective is a package of Minuet, developed by the University of Minnesota (USA). Package Minuet has a full range of services of Internet, as well as an excellent user interface. Minuet easy to use, can operate as a LAN and dial-up lines and, most importantly, much cheaper than their counterparts. Undoubtedly package Minuet is currently the best subscriber package for OS MS DOS. It may be recommended in almost all categories of subscribers.

For operating MS-DOS, the best package of subscription software from the perspective of a specialist is a package KA9Q. Package KA9Q distributed with source code and has a full range of network services, it can be recommended to specialists in the network as an input in the development of a new package of subscription software.
For the operating environment MS-Windows the best package subscriber programmnogo of the package can be found Chameleon, which is a development company NetManage (USA). Package Chameleon has a complete set of services on the Internet. Besides Chameleon has in its composition NFS-server, and can also run router network. To date, Chameleon can be recognized as the best package for the operating environment MS Windows. Package Chameleon can be recommended to subscribers of the network that require subscription package software for MS-Windows. It may also be recommended as a router to connect a small LAN with a network
Best email package for OS MS-DOS environment is certainly a package MAIL2, developed by PC-Techno Center (Russia). Package Mail2 has an excellent user interface, easy to setup and inexpensive. It can work both in LAN and dial-up lines. It can be recommended to all categories of users.

Best email package for the operating environment MS-Windows can be considered as a package DMail for Windows, developed by Demos (Russia). Package DMail can be recommended to use those subscribers who require e-mail and used to working in Windows.

Best package for the fullest use of information resources of the Internet is a package of Mosaic, developed by NCSA (National Centre of Supercomputing Applications) USA. Mosaic - the most powerful tool for travel on the Internet. With Mosaic, users can access hypertext libraries, WWW, to conventional databases, the Internet and finding information in them.

During graduate prektirovaniya for packages Minuet, Mail2 and developed instructions for installation and maintenance of subscriber data packet software. Packages Chameleon and Dmail sold together with a full set of proprietary documentation package Mosaic is distributed free along with a fairly complete documentation.

Computers and Software 4

TCP / IP protocol makes it possible to transmit information, but it used a variety of network services in different ways to manage this information. Internet has not solved the problem of storing and ordering information, but solved the problem of transmission, making it possible to get it anytime, anywhere. Since Network (hereinafter referred to as network-with a capital-would mean the Internet) is decentralized, then turn off, even a large part of the computers will not affect its functionality. According to analysts, in 1995 the number of fully networked computers accounted for about 7 million and continues to grow rapidly. By the same estimates, at the beginning of the next century the network may be as accessible as the telephone or television today.

In the web there are a large number of services. We will continue to be interested in the WWW or simply Web (Word-Wide Web-the World Wide Web). This is the most popular web service and convenient way to work with information. Today, there are at least 30 thousand servers, WWW. It is through the WWW network is growing so rapidly. Using simple language descriptions can be Hypermedia documents for subsequent publication in the web (I mean a hypermedia document that can contain all kinds of information - from simple text to multimedia clips). To see the contents of the document as it imagines the author must have client-side viewer browser. The most popular today, Netscape Navigator, supports many extensions to HTML (Hyper Text Markup Language-Hypertext Markup Language documents - namely with the help of formalized information in WWW). Further, under words the browser or viewer I mean is this program, although not excluded that some other program is able to display all the way it was intended.

Now a little information about the technology "client-server". It has been known for quite a long time, but had often been used in large scale enterprise networks. Today, with the development of Internet, this technology is increasingly attracting the eyes of software developers. The world has accumulated a wealth of information on various issues. Most of this information is stored in databases (DB). To publish it in the web had to export the database in HTML-documents, which required costly and complicated the search for information. Today there is wide experience of similar works. Almost every web user is often faced with such a database. For example, the main thing in the popular search engine Yahoo (address-http:: \ \ www.yahoo.com) - a query to a database of WWW-server keywords. A server-list of hypertext links found in web pages that contain the necessary information. It is today the problem of Web-interface to the database as never before.
Internet - a global computer network covering the whole world. Today the Internet has 15 million subscribers in more than 150 countries. Monthly size of the network increases by 7-10%. Internet forms the core, providing us various information networks belonging to various institutions throughout the world, with one another.
Previously the network was used exclusively as a medium for file transfer and e-mails, now solve more complex problems of distributed access to resources. About two years ago created a shell that supports a network search function and access to distributed information resources, electronic archives.

Internet, which served as a purely research and academic groups, whose interests extended until access to supercomputers, is becoming increasingly popular in the business world.

Companies tempt fast, cheap global communication, convenience to carry out joint operations, the available programs, a unique database on the Internet. They see the global network as a complement to their own local networks.
With a low cost of services (often only a fixed monthly fee or telephone line used), users can gain access to the commercial and noncommercial information services USA, Canada, Australia and many European countries. The archives of free access to the Internet can find information on almost all spheres of human activity, from new scientific discoveries to the weather forecast for tomorrow.
Besides Internet provides unique opportunities for cheap, reliable and confidential global communications around the world. This is very convenient for companies with branches all over the world, transnational corporations and governance structures. Typically, the use of Internet infrastructure for international communication is considerably cheaper than direct computer connection via a satellite channel or via telephone.

E-mail - the most common service on the Internet. Currently your address by e-mail are approximately 20 million people. Sending emails is considerably cheaper than sending regular letters. Besides the message, sent by e-mail reaches the recipient for several hours, while an ordinary letter can reach the recipient several days or even weeks.

Currently, Internet is experiencing the period of recovery, thanks largely to strong support from European governments and the United States. Every year in the United States allocated about 1.2 million dollars to build new network infrastructure. Research in network communications funded by the Governments of Great Britain, Sweden, Finland and Germany.

However, public money - only a small part of the inflows, as more visibly "kommertsizatsiya" network (it is expected that 80-90% of the funds will come from the private sector).

Community reshivshie connect your computer to the network should pay special attention to the protection of information. Strict requirements for protection of information related to the fact that the connected computer is accessible from anywhere in the network, and therefore a much more exposed to defeat viruses and nesanktsioirovannomu access.

So non-compliance regime for the protection from unauthorized access could lead to information leaks, and failure modes of protection against viruses may lead to failure of critical systems and destroy the results of many days of work.
Computers operating in multitasking operating systems (such as Unix, VMS) enough to become infected with viruses, but they should be very carefully protected from unauthorized access. In this regard, users are multitasking operating systems must fulfill the following requirements.

Each user must have their own individual login to the Unix-server and a password.
Installed for users' passwords are not required to report to others.
Changing the password the user must perform at least once per quarter, as well as in all cases of leakage of information about the password.
Administrators and users of file-servers NetWare LANs must also follow the above requirements within their LAN. This is due to the fact that if a file server connected to the network, loaded utility Iptuunel, then the file server also becomes accessible from anywhere in the network.

PC working in odnozadachnyh operating systems (such as MS-DOS), suitably protected from unauthorized access (by virtue of their odnozadachnosti), but they should be particularly careful to protect from the virus.

To protect against viruses is recommended to use security software (such as aidstest), as well as hardware and software (such as Sheriff).

Computers and Software 3

To date, there are more than 130 million computers and com ¬ ¬ more than 80% of them are combined in various information and computer networks from small local area networks in offices to global networks, the type of Internet. Global trend towards the unity of the object ¬ of computers on the network due to a number of important causes, such as accelerating the transfer of information redachi ¬ ¬ formation message, the possibility of rapid exchange of information between users, receiving and sending messages (fax, E - Mail letters and other things) without leaving the workshop place, the possibility of an instant receipt any information of any battle ¬ point of the globe, as well as on ¬ Myong information between computers of different manufacturers of Dr. Bo ¬ ¬ melting under a variety of software.

Such great potential which has a calculator ¬ net loss and the new potential to rise while the information is ¬ tion complex, as well as a significant acceleration of the production process does not give us the right not to take it to develop ¬ al, and not to apply them in practice .

It is therefore necessary to develop a principled solution to the issue of organizational ¬ tion IVS (information and computer network), based on an existing computer ¬ tion park and software complex answer ¬ forthcoming modern scientific and technical requirements, given the increasing ¬ ing needs and opportunities for further development of post ¬ foam network in connection with the emergence of new hardware and software solutions.

Today, many people surprised themselves discover the existence of global networks of computers worldwide in a single information space, called the Internet. What is it, is not easy to define. From a technical point of view of Internet - an alliance of multinational computer networks operating on different protocols, linking various types of computers, physically transferring the data from all available types of lines - from the twisted pair and fiber optic telephone cables before and satellite channels. Most of the computers connected to Internet Protocol TCP / IP. We can say that the Internet-a network of networks that beset the globe.

Computers and Software 2

After some time, TCP / IP has been adapted to the normal, ie, in a public standard, and the term Internet came into general use. In 1983, the ARPANET was made from the MILNET, which was a treat to the Defence Data Network (DDN) U.S. Department of Defense. Internet has become a term used to refer to a single network: MILNET plus ARPANET. And while in 1991 ARPANET ceased to exist, the Internet exists, its dimensions are much greater than the original, as it brings together many networks around the world. Figure 1 illustrates the increase in the number of hosts connected to the Internet network with 4 computers in 1969 to 3.2 million in 1994. Hosts on the Internet referred to as computers, operating in multitasking operating system (Unix, VMS), supports the TCP \ IP and provide users with any network services.
Currently on the Internet used by virtually all known lines from low-to high-speed phone lines, digital satellite channels. Operating systems used in the Internet, as distinct variety. Most Internet network of computers working under operating system Unix or VMS. Widely represented as special types of network routers NetBlazer or Cisco, whose operating systems like OS Unix.

In fact, Internet is composed of many local and global networks of various companies and enterprises linked by the various lines. Internet can be imagined as a mosaic of folding of small networks of various sizes, which actively interact with one another, sending files, messages, etc.

An example of the topology of the Internet can serve as a network of H-atom, consisting of several sub-networks, and at the same time is a bit of a worldwide network of Internet.

Computers and Software

In 1961, the Defence Advanced Research Agensy (DARPA) assignment to the U.S. Department of Defense has begun a pilot project to establish a network packet. The network, called ARPANET, was originally designed to study methods to ensure reliable communication between computers of different types. Many methods for data transmission via modems were developed in the ARPANET. At the same time, have developed protocols and data transmission on the network - TCP / IP. TCP / IP - a set of communication protocols that define how different types of computers can communicate among themselves.

Experiment with the ARPANET was so successful that many organizations want to enter into it, to be used for daily data. And in 1975, the ARPANET evolved from a pilot network in a working network. Responsibility for administration of the network has taken the Defence Communication Agency (DCA), now known as the Defence Information Systems Agency (DISA). But the development of ARPANET are not stopped, TCP / IP protocol continued to evolve and improve.

In 1983, the first standard for the protocols TCP / IP, which entered the Military Standarts (MIL STD), ie military standards, and all who worked on the network, have been obliged to move to these new protocols. To facilitate this transition DARPA to invite the leaders of Berkley Software Design - implemented TCP / IP protocols in the Berkeley (BSD) UNIX. From this union, and began UNIX and TCP / IP.