• The local computer network is operational. Connecting computers into a local network. Organization of user work in local computer networks. Required Hardware

    The computer on which the user is logged in. In other words, it is a computer that is directly accessible to the user, that is, without communication lines and devices such as a network card or modem.

    local user

    User of a computer not connected to the network. Usually local users called people working with a computer at home.

    remote computer

    A computer that is accessible to the user only through the use of communication lines and devices, such as a network card or modem.

    protocol

    A set of rules for exchanging data between computers on a network, including the Internet. The protocol describes the rules for the exchange of service information that ensures data integrity.

    OSI reference model

    A network model proposed by the International Standards Organization (ISO) to enable interoperability between suppliers. The OSI model is a conceptual seven-layer model (figure), including the following levels:

      applications,

      performances,

    1. transport,

      data channel,

      physical levels.

    Ethernet network

    IEEE 802.3 standard for adversarial networks. An Ethernet network uses a bus or star topology and CSMA/DC (Carrier Sense Multiple Access with Collision Detection) access control method to regulate traffic over the communication lines. Network nodes are connected by coaxial or fiber-optic cable or twisted pair. Data is transmitted in variable-sized frames containing control and address information, as well as up to 1500 bytes of data. The Ethernet standard provides data transmission without high-frequency modulations at a speed of 10 megabits (10 million bits) per second.

    Wireless network

    A data transmission system that uses a radio channel as a carrier. Allows you to deploy a network where deploying a cable system is impossible or economically infeasible.

    Router

    In the Windows environment, routers are devices that provide compatibility between local and wide area networks, as well as the ability to connect local networks with different topologies (such as Ethernet and Token Ring). Routers check packet headers against some local network and choose the best path for the packet, optimizing network performance.

    In a Macintosh environment, routers are needed to connect computers on different physical networks. Routers maintain a table of physical networks on a Macintosh internetwork and forward data received from one physical network to other physical networks. The functions of routers can be performed by computers with server versions of Windows and running integration services with the AppleTalk network. Additionally, a network integrated with an AppleTalk network may use different routing equipment.

    Routing

    The process of forwarding packets across an internetwork from a source node to a destination node.

    shared folder

    A folder located on another computer that can be accessed over the network by other users.

    shared resource

    Any device, data, or program shared by multiple devices or programs. In Windows, shares are any resources that are accessible to network users, such as directories, files, printers, and named pipes. The term is also used for server-based resources available to network users.

    bits per second

    The number of bits transmitted per second; used as a unit of measurement for the speed at which a device, such as a modem, can transmit data.

    A single set of OSI (Open Systems Interconnection) network layer binary data consisting of transmitted data and a header containing an identification number, source and destination addresses, and error control data.

    protocol

    A set of rules and conventions for transmitting data over a network. Such rules determine the content, format, timing, sequencing, and error checking of messages exchanged between network devices.

    working group

    Computer pooling designed to make it easier for users to find items such as printers and shared folders. Workgroups in Windows, unlike domains, do not provide centralized account provisioning and authentication.

    Global networks

    global network

    A communications network connecting geographically distant computers, printers and other devices. A global network allows connected devices to communicate with each other. /1/

    Internet

    A global information network, parts of which are logically interconnected with each other through a single address space based on the TCP/IP protocol. The Internet consists of many interconnected computer networks and provides remote access to computers, e-mail, message boards, databases, and discussion groups.

    Intranet

    A distributed corporate computer network designed to provide employees with teleaccess to corporate information resources and using software products and Internet technologies. The intranet allows you to control access to corporate information.

    Internet service provider

    An organization that provides Internet access to companies and individuals. Your ISP provides the phone number, user name, password, and other information that users need to connect their computers to their ISP computers. Typically, provider fees can be paid monthly or hourly.

    Internet server

    A computer connected to a network, or a program running on it, that allows clients to access and manage shared resources.

    Each computer connected to the Internet has two equivalent unique addresses: a digital IP address and a symbolic domain address.

    The most important server types are:

      web servers;

      email servers;

      FTP servers for file sharing;

      real-time communication servers (chat);

      servers providing Internet telephony;

      systems for broadcasting radio and video over the Internet.

    A local area network is a group of computers connected together, located in a specific limited area, such as a building. The size of such a network can vary. It can include from two workstations located in the same room to several hundred workstations located on different floors of one administrative building. In most cases, different types of cables can be used to connect computers into a single network. However, the use of wireless channels is also acceptable, which will also be discussed. So, let's figure out what a local network is? It is important to note that if the network leaves the boundaries of one building, then it would be more correct to call it global. In general, from the specialized literature it can be determined that the local network is limited to the boundaries of the building, but for the global network there are no such restrictions.

    The literary definition does not always correspond to accepted standards, since the network is usually defined by functional rather than physical features. In this sense, which is the most general, such networks are a means of connecting computers, allowing them to access different equipment. That is, such computers gain access to various kinds of network resources, for example, printers, scanners, as if they were installed locally. Naturally, access to equipment also means access to data available on this equipment.

    So, in the question of what a local network is, everything may already seem clear. However, there are a lot of nuances here too. All computers on such a network are capable of not only accessing the installed network components, but also using them in the same way as during a local installation, which implies mandatory joint implementation of data.

    The first local connected office generations - mainframes into a network, however, the first personal machines were usually installed as separate devices. It is worth mentioning the most primitive form of local network, when the user copied them to a floppy disk on one device, and then moved to another to print the information or simply save it there. This decision could not be called bad, especially considering the possibility of copying large amounts of information. However, there are also shortcomings here, and very serious ones:

    The risk of information loss due to data loss or accidental formatting was very high;

    Difficulties arose with synchronizing different versions of a document when several people had to work on it at the same time;

    The floppy disk size was only 1.44 MB, and the size of the required data file could significantly exceed it;

    The inability of users to work with documents when using various pre-installed applications on computers;

    The data was difficult to protect, since the floppy disk could simply be stolen;

    A significant amount of time is spent on the processes of copying files, transferring them to another machine, as well as subsequent operations with it.

    That is why such networks were suitable only for solving primitive problems. So, what is a local network in the current sense? Modern office facilities must meet new requirements:

    Sharing, protecting and transferring data;

    Applications must be shareable;

    Users should be comfortable interacting with each other;

    Peripheral devices must be made available to all machines.

    Now you know not only what a local network is, but also what the principles underlying it are.

    Network is a single complex that includes a geographically dispersed system of computers united into a single system by means of communication using communication equipment, software and protocols for solving information, management, computing and/or other problems.

    Local network(Local Area Network - LAN) connects computers and peripheral equipment within one or more adjacent buildings. The network organized within the office is also local. The main purpose of a local network is to share the resources of one computer with another computer(s). Thus, a local network allows you to share files, applications, peripheral devices (printers, scanners, etc.), work with email, use instant messaging, participate in electronic conferences, etc.

    The principle of construction (configuration) of network connections is called topology. Based on topological characteristics, local networks can be represented by three basic topologies: common bus, star, ring.

    By topology common bus(backbone) all computers are connected to one cable (Fig. 118).

    At the ends of the cable there are terminators(energy absorbers) that serve to prevent signal reflection. The message sent by the workstation is distributed to all computers on the network. Each machine checks who the message is addressed to, and if it is addressed to her, then processes it. In order to exclude the simultaneous sending of data, either a “carrier” signal is used, or one of the computers is the main one and “gives the floor” to the other stations.

    Rice. 118.

    Advantages of such a construction are:

    • - a simple structure that allows you to expand the network by adding more computers;
    • - low cost of implementation;
    • - the network is easy to set up and configure.

    Flaws:

    • - low efficiency due to loss of productivity with the addition of new workstations;
    • - network problems, such as a cable break, completely block the operation of the entire network.

    This topology is used in local networks with architecture Ethernet(technology and architecture for building large local computer networks). Data transmission in networks of this type is possible via coaxial cable at a speed of 10 Mbit/s (10Base-5 and 10Base-2 standards), twisted pair cable (10Base-T standard) and fiber optic cable (10Base-F standard).

    In a topology like "star"(Fig. 119) each computer is connected by a cable (twisted pair) to hub(habu). A hub allows workstations to be connected in parallel so that all computers connected to the network can communicate with each other.

    The workstation from which data needs to be sent sends it to the hub, which determines the recipient and gives him the information. At a given time, only one machine on the network can send data; if two packets arrive at the hub at the same time, both packets will be rejected and the senders will have to wait a random period of time to resume data transmission.

    Advantages topologies:

    • - failure of one computer does not affect the operation of the entire network as a whole;
    • - good network scalability - easy to connect a new computer;
    • - easy troubleshooting and network breaks;
    • - high network performance.

    Flaws star topologies:

    • - failure of the central hub will result in the inoperability of the network (or network segment) as a whole;
    • - high cable consumption, especially if the hub is not located in the center of the topology;
    • - the finite number of workstations in a network (or network segment) is limited by the number of ports in the central hub.

    Rice. 119 .

    In a network with a topology "ring"(Fig. 120) all nodes are connected by communication channels into an unbreakable ring through which data is transmitted. All data on this network is transmitted from one station to another in one direction. Each computer works as a repeater, restoring and amplifying signals.

    TO merits Ring topologies include:

    • - ease of installation;
    • - almost complete absence of additional equipment;
    • - the possibility of stable operation without a significant drop in data transfer speed under intense network load.

    Flaws Ring topologies are as follows:

    • - if one computer fails or the cable breaks, the ring “breaks”;
    • - connecting a new computer leads to a short-term network shutdown;
    • - complexity of configuration and setup;
    • - Difficulty in troubleshooting.

    Rice. 120.

    Exists two main types of local networks, based on the computer connection scheme: client/server and peer-to-peer network.

    IN networks server based(rice. 121) there is a dedicated server- a specialized computer that controls the use of resources shared between workstations, such as external memory, printers, databases, etc.


    Rice. 121.

    There are several types of servers, in particular:

    • - mail server- manages the transmission of electronic messages between network users;
    • - file server- manages the creation and use of local network information resources, including access to its databases and individual files, as well as their protection. For example, when working with a test editor, the file is stored on a file server and will be loaded into the memory of your computer;
    • - application servers- controls the operation of the local network when performing any application tasks. Examples of this kind of tasks can be: ensuring communication with other local and/or telecommunication systems, collective use of printing devices, etc.;
    • - proxy servers- can store frequently requested information in cache memory on a local disk, quickly delivering it to users without re-accessing the Internet;
    • - print servers- allow all computers connected to the network to print documents on one or more shared printers. In this case, there is no need to equip each computer with its own printing device. In addition, by taking on all the worries about printing documents, the print server frees up computers for other work.

    The advantages of a network with a dedicated server include, in particular, the following.

    • 1. High performance, since a high-performance computer is installed as a server, with significant amounts of internal and external memory, a powerful central processor, etc.
    • 2. Support for a significant number of workstations.
    • 3. The ability to implement access control, which means that you can limit the user’s access to various resources, which increases the security and protection of data.
    • 4. Possibility of backup storage, since the data is stored on the server.

    There is no dedicated server in a peer-to-peer network (Fig. 122), all computers

    equal rights, i.e. each user personally decides what data on his computer to provide for public use.

    To organize constant communication between computers on a peer-to-peer local network, they are combined into work groups.

    Working group- this is a group of people (for example, employees of an organization) who are engaged in one project. The computers in each workgroup form a separate segment.

    LAN segment- part of the network cable, limited routers(a device designed to provide access to remote local networks and the Internet, as well as to organize communication between networks and their interaction), repeaters, terminators and other additional devices.

    A separate group includes print servers with several conventional printers connected to them, which at the same time acquire network capabilities and can work over the network, regardless of whether they support this operating mode. Typically print servers have LPT connectors. Such servers are used in large organizations, but at home it is enough to have one printer on a computer connected to a local network so that all computers in the workgroup can access it. All of the above can be expressed in a single term - "shared access to resources."


    Rice. 122.

    Thus, a peer-to-peer network is convenient to use in teams of up to ten people, taking into account the fact that the network is not expected to scale in the near future.

    The advantages of a peer-to-peer network include:

    • 1. Cheapness of building a network due to the use of shared printers and other peripheral devices.
    • 2. No special software or powerful computer is required as a server.
    • 3. High qualifications are not required when installing and administering the network.

    The disadvantages include:

    • 1. Low security, since insufficient security of one workstation can lead to infection of other computers with viruses.
    • 2. Quite low productivity, since no special requirements are imposed on the workstation.
    • 3. Users must have sufficient qualifications to solve problems that arise during operation.

    Currently, in any store, office or enterprise it is impossible to work quickly and fully without a local network into which all employee computers are connected. LAN is also used at home or other places where there are multiple computers.

    To organize user work on a local computer network, a number of requirements must be met, including:

    • 1. A network cable must be connected to the computer.
    • 2. A network card is installed as an additional device.
    • 3. The connection to the local network has been configured.

    Other settings can be made even by an inexperienced user. In particular, in order to set the workgroup name, which other computers, say, in your office or organization have. To do this, click on the button Start, go to item Computer, by clicking the right mouse button go to the menu item Properties. The window shown in Fig. will open. 123.


    Rice. 123.

    Let's pay attention to the bottom part of the window, labeled as Computer name, domain name, and workgroup settings. There is a link on the right Change settings by clicking on which the user can change the computer name and workgroup name.

    Another setting is related to providing shared access to folders. To make a folder visible on the network, you must perform the following steps:

    • 1. Find the folder to which you are going to share access, suppose the folder Documents.
    • 2. Right-click on it.
    • 3. Go to item Specific users and in the window that opens (see Fig. 124) press the button General access.

    Rice. 124.

    After this, the folder will be shared with all users on the local network. If you need to deny access to a folder to which it was previously granted, then you should follow the steps described above, only when you complete step 3, click on the button Terminate access.

    When working together on a local network, it is possible for other users to use your printer, scanner, fax, etc. In order to provide access to your resources, you must complete the following steps:

    • 1. Enable the printer sharing feature. To do this, run the following command Start/Control Panel/Network and Internet/Network and Sharing Center. On the left side of the window, select Change advanced sharing settings.
    • 2. Select the desired profile. Activate option Enable file and printer sharing. A similar situation is shown in Fig. 125.

    Rice. 125.

    • 3. Run the command Start/Devices and Printers. Right-click on the desired device, select Printer properties.
    • 4. Go to tab Access and check the option Share this printer. The network name of the printer is also set here.
    • 5. Click on the button OK.
    • 1. Define the concept of “network”? What is the main purpose of local networks?
    • 2. What is topology?
    • 3. Draw a diagram of how computers are connected using a common bus topology. What are the advantages and disadvantages of this topology? What are terminators used for?
    • 4. Draw a diagram of how computers are connected using a star topology. List the advantages and disadvantages of this topology. What does the hub provide?
    • 5. Draw a diagram of how computers are connected using a “ring” topology. Explain the advantages and disadvantages of this topology.
    • 6. Draw a diagram for constructing a local network based on a server and describe it.
    • 7. Name the types of servers and give them characteristics.
    • 8. List the advantages of a dedicated server network.
    • 9. Draw a diagram of a peer-to-peer network and describe it.
    • 10. For what purposes are working groups created? What is a LAN segment?
    • 11. Name the advantages and disadvantages of peer-to-peer networks.
    • 12. Determine what type of network is used in your computer classroom. Draw its diagram.
    • 13. Together with your teacher, try to graphically draw a diagram of the networks of your educational institution.
    • 14. What are the requirements for organizing user work on a local network?
    • 15. Show practically how to set a workgroup name and share folders on a specific computer.
    • 16. Demonstrate how you can provide access to local computer resources to other users.

    Workshop

    Concept of system administration

    With the increasing use of computers, systems administration is becoming a key area in more and more organizations. The administrator must understand his system, know its users and their occupation. The main thing in administration is the ability to plan, since in the conditions of creation, modernization and expansion of systems, an attempt to improvise and develop network solutions on the fly is doomed to failure.

    Network administrator (system administrator)- a specialist whose responsibilities include performing the following main functions:

    • - installation of the operating system and application programs;
    • - description of the information environment;
    • - setting up the operating environment;
    • - setting up network printing;
    • - network monitoring and management of network resources;
    • - archiving and restoring network data.

    Let's look at them in more detail.

    Installation(English, installation) - the process of installing software on a computer. During the installation of the operating system, the administrator must answer a number of questions interactively.

    Description of the information environment- includes the following actions:

    • - creation of user directories;
    • - assigning access rights to directories and files;
    • - assigning attributes to directories and files.

    Setting up the operating environment includes:

    • - installation of configuration files for workstations;
    • - development of system and user procedures for connecting to the network;
    • - workstation management.

    Setting up network printing suggests description:

    • - print objects (queues, printers, print servers);
    • - print forms (paper size);
    • - configurations of print jobs.

    Network monitoring- assessment of its performance and reliability characteristics. Using special software packages you can implement:

    • - monitoring of file servers and network segments;
    • - management of a file server, hubs, workstations.

    Archiving and restoring network data. IN case of large volume

    of archived data, all computers involved in the archiving process must have a high-speed (100 Mbit/s or higher) connection to the local network. Otherwise, the archiving process may take considerable time.

    In addition to the above functions, the system administrator must know the basics of information security. This concept includes the protection of information located on personal computers and servers of the enterprise local network from unauthorized access, intentional distortion and damage. This concept also includes anti-virus protection of the local network and individual computers from virus attacks, all kinds of Trojan programs, malicious macros and software bookmarks.

    In addition to the listed professional knowledge, the administrator must have communication skills, non-conflict, patience, know the basics of psychology and conflict management, since he is the link between computer technology and those who work on it.

    The risks of the Internet are associated solely with its uncontrollability. Being a colossal source of information, the Internet does not divide it into good and bad or useful and useless. In addition, the Internet is ultimately a paid resource, i.e., the consumption of information from it must be paid for by someone.

    The main disadvantages of uncontrolled use of the Internet in organizations are the following:

    • - user access to harmful and useless information, which entails distraction from the work process;
    • - penetration of viruses and worms into the enterprise network;
    • - cost overruns due to non-work-related Internet activity of users.

    To effectively combat the risks described above, you need a system that performs three critical functions:

    • 1.Accounting for the consumption of Internet resources. If employees know that their every “step” on the global network is monitored, this will reduce traffic and prevent misuse of the institution’s funds. It will be possible to easily find out which resources are visited by users during working hours.
    • 2. Internet access control. In order to be able to specify which employees can have access, when and where. This will reduce lost work time and improve safety.
    • 3.Network protection from information leakage, hacker attacks, network viruses and worms. This component is necessary to ensure the security of the enterprise network.

    Differentiation of access rights in the network

    Ensuring information security allows differentiation of user access rights to working documents and annexes. Each employee gets the opportunity to work only with those resources that he needs, while all documents are protected from accidental or intentional viewing or modification.

    Currently, there are a number of programs on the market that provide, in particular, control and management of Internet access, protection of users and enterprise networks, traffic accounting, anti-virus protection and content filtering of web traffic. Conventionally, they can be divided into several categories:

    Free programs, which can be downloaded from the Internet. But, as a rule, such programs are designed to solve individual problems. There are programs for collecting statistics, but they do not have the ability to process data according to various parameters. Conversely, there are programs for limiting resources that do not have statistics collection functions, etc.

    An example is the BWMeter program, designed for graphically displaying and counting traffic that is transmitted over a local network. Using the utility, you can count transmitted packets, as well as find out where and from where they are sent, through what protocol and to what port.

    Paid solutions on the protection and control of corporate information can be purchased on CDs on the Internet. Professional solutions of this kind from well-known foreign manufacturers, as a rule, meet all the above requirements, but are expensive. This category includes programs such as Kerio WinRoute Firewall, Ideco ICS Standard Edition, UserGate proxy server, Windows Svr Ent 2008.

    Hardware and software systems to control Internet connection. They are convenient because their functionality is focused specifically on the end user, i.e., companies of any level, meet all requirements and are easy to use. Their main advantage is that you do not need to select equipment and install software. A hardware-software complex or simply a server connects to the network, is configured to its characteristics and works. An example is the Internet Control Server 2.x software package, which is installed on a computer and separates the corporate network from the Internet, controlling all information flows and accounting for traffic between the institution’s network and the Internet.

    On the tasks of delimiting access rights in the network can be attributed:

    • 1. Distribution of users into groups and creation of an account for each group and user separately.
    • 2. User authorization.
    • 3. Prohibition of access to certain objects.
    • 4. Setting restrictions on the consumption of Internet resources.

    In order to distribute users into groups, it is necessary to create a user structure using an analysis of the organization, for example, highlight all departments, think through the characteristics for identifying user groups. For example, the following structure is possible: planning and financial department, accounting department, personnel and office management department, etc. For dedicated departments, you need to create groups and create users within them, or do it differently - create users without groups. In principle, there is not much difference here. The only advantage of creating groups is the ability to track consumption for the group as a whole. Using access profiles, you can easily set the same access rights for individual users who are not grouped together. Of course, for groups there is no need to create an access profile.

    How does user authorization work? When opening a new browser window and requesting a resource from the Internet, the user receives a window asking for a login and password. In this window, you should enter the login and password for this user, which were assigned to him during creation. If the login and password are correct, the user gains access to the Internet.

    For implementation prohibiting access to certain objects you need to create a locking system that works according to the following example:

    User 1

    User 2

    User 3

    With this structure, “user 3” will be denied all three resources (www.yandex.ru, www.google.com and www.auto.ru), “user 2” will have only the top two - Yandex and Google, “User 1” will have access to any resource except www.yandex.ru.

    It is also worth noting that each of the users from the example above must have explicit permission to access any (!) resources. There will be no disruption as the rules of higher groups will also apply. That is, taking this into account, the example will look like this.

    All users (www.yandex.ru is prohibited)

    User 1 (all allowed)

    User 2 (all allowed)

    User 3 (all allowed)

    The sequence in which rules are added affects the priority of the rules (the higher the rule is located, the higher its priority over the others).

    The network administrator may need to set a certain set of prohibiting/permitting rules for a whole set of users who are located in different groups. So that he does not have to manually add this set of rules separately for each user, it is possible to create a so-called access profile with the appropriate set of rules and then add it to the list of access rules for each individual user.

    As already mentioned, the Internet is a paid and public resource. Therefore, saving money for an educational institution and, in addition, limiting channel capacity for specific users in order to more equitably distribute channel capacity among all users are of great importance. To do this you need to set restrictions on resource consumption Internet.

    In this regard, the following characteristic is introduced: the maximum volume of traffic consumption (quota), if exceeded, the network administrator can take various punitive measures.

    By tracking the dynamics of traffic consumption by users, the network administrator can determine the average maximum traffic volume, if exceeded, it is possible, for example, to disconnect the user who has violated the rules from the Internet without warning.

    Not a single network administrator of an educational institution will allow ordinary users (students) to perform the above-described functions of delineating access rights in the network during practical classes. However, on a regular school or home computer you can consider, in particular, account creation process. The fact is that quite often situations arise when several people work on one computer, and in this case you can make sure that each user has their own Windows settings. In addition, you can give some users the ability to install new software, while denying others. It is also possible to prohibit the use of certain programs on the computer.

    There are three types of accounts. Each type gives the user different options for controlling the computer:

    • - regular user accounts are intended for everyday work;
    • - Administrator accounts provide full control over the computer and are used only when necessary;
    • - Guest accounts are intended for temporary access to the computer.

    In other words, when you log into Windows using the normal

    account can perform the same actions as an administrator account, but Windows may require an administrator password to make changes that affect all users on the computer (for example, installing software or changing security settings).

    To create a new account, run the command Start/Control Panel/User Accounts and Family Safety. The window shown in Fig. will open. 126.


    Rice. 126.

    Let's select an item Adding and removing user accounts. IN

    in the window that appears (Fig. 127), select the item Create an account.

    Rice. 127.

    Rice. 128.

    Next you need to specify the account name and access rights (Administrator or Regular access) which the owner of the account being created will have to have (Fig. 128), and click the button Create an account.

    Your account has been created and now you need to configure it. To do this, double-click on the created account.

    In the window shown in Fig. 129, there are the following points:

    • 1. Change the account name.
    • 2. Create a password.
    • 3. Changing the pattern.
    • 4. Set up parental controls.
    • 5. Changing the account type.
    • 6. Managing another account.

    Rice. 129.

    Let's comment on some of them. First, after creating an account, you need to create a password for it (Fig. 130). Using a password increases system security. Field Enter a password hint may not be filled out. After entering the password and duplicating it, click on the button Create a password.


    Rice. 130.

    Set up parental controls. A new feature in Windows 7 allows you to set the time when the user (child) can use the computer, as well as determine what games and programs will be available to him. With parental controls you can:

    • - limit the time spent by the user (child) at the computer. You can limit the amount of time children are allowed to log in. For each day of the week, you can set aside a time to log in to the system, even if the user works at the computer, the system will automatically log out;
    • - set a ban on access to certain games. You can control access to games, choose the appropriate age rating, what types of content should be blocked, and set whether or not to allow or deny access to specific or uncategorized games;
    • - establish a ban on the user (child) using certain programs.

    For implementation prohibiting access to certain objects, in particular, for Internet resources, you should install the additional module “Family Safety”, located at http://windows. microsoft.com/ru-RU/windows-live/essentials-other-programs (Fig. 131). However, in this case, you will first need to obtain a Windows Live ID from the Windows Live service at http://www.home.live.ru.

    By installing the core components of Windows Live on your computer, you can enhance your experience with photos, videos, and email. The core components of Windows Live are free and include Windows Live Messenger, Photo Gallery, and Movie Maker. With a Windows Live ID, you can access all Windows Live services, including Hotmail, SkyDrive, and Messenger, with one sign-in.


    Rice. 131.

    After registering and installing the Family Safety component, options will become available for filtering and blocking Internet resources that, in your opinion, are undesirable for the user to visit. They include the following sections:

    • 1. Web filter.
    • 2. Create an action report.
    • 3. Contact management.
    • 4. Requests.
    • 5. Time restrictions.
    • 6. Game restrictions.
    • 7. Program limitations.

    The settings will be available at http://familysafety.live.com if the system administrator first enters a Windows Live ID and password.

    After entering the password, a window with the above parameters will appear on the screen (Fig. 132).

    Let's look at some of the parameters.

    Web filter. With its help, you can control what types of websites users (children) can view and track the sites they visit (Fig. 133). In particular, you can allow visiting web resources only from the white list, added by the administrator (parent), block adult sites, allow or prohibit communication on social networks.


    Rice. 132.


    Rice. 133.

    Web filter lists. With their help (Fig. 134), you can manage the list of websites that are allowed or blocked for the user (child). By compiling a list of specific sites in advance, the administrator (parent) can allow or block access to them.

    Time restrictions. In a special dialog box (Fig. 135) you can select the time when the user (child) is allowed to use the computer. In the clock grid, white rectangles indicate allowed hours of access to the computer, and blue rectangles indicate prohibited hours.


    Rice. 134.


    Rice. 135.

    Game restrictions. Each game has its own rating, i.e. the rating of the category of people for which it is intended, for example, the game is allowed for children over 3 years old, over 6 years old, over 10 years old, etc. In accordance with these assessments, one or another category of games can be allowed/prohibited. The window for setting game restrictions is shown in Fig. 136.


    Rice. 136.

    Application restrictions. The corresponding window (Fig. 137) will list the programs installed on the computer, from which you can select those that are not allowed to be used.


    Connecting your computer to the network

    So, we have considered issues related to the differentiation of access rights on the network and on the user’s computer, and we have gained the concept of system administration. However, we assumed that the local network was already configured and the computer with the operating system installed was connected to the local network. Now it's time to meet connecting your computer to the network and settings associated with this process. It should be noted that such actions will most likely be prohibited by the educational institution’s network administrator, so you can view the general progress of connection work on your personal computer without changing its settings in any way.

    Firstly, a network card must be installed on the computer connecting to the network, secondly, a network cable must be connected to it, and thirdly, an agreement must be concluded in advance with the network service provider.

    By executing the command Start/Control Panel/Network and Internet/View network status and tasks, the user will see the window shown in Fig. 138.


    Rice. 138.

    Typically, within a few seconds of turning on your computer, Windows 7 detects and configures your home network settings. Otherwise (in our example), the straight line connecting the SERGEY-VAIO section (this computer) - Multiple networks would be crossed out with a red cross. If a red cross appears on the site Network - Internet(Fig. 139), this means that there is no connection to the Internet.

    Rice. 139.

    If you place your mouse pointer over the red cross, the message “Click here to troubleshoot” will appear. After clicking the mouse it will start Troubleshooting Wizard. However, those recommendations that Master will be issued at the end of the diagnostic process; only an experienced user can help. Even if you forcefully disconnect the network cable, Master will not display the message “Your network cable is disconnected”, but will inform you that you need to restart the modem.

    In order to configure the computer’s connection to the network, in the window Network and Sharing Center(see Fig. 138) select item Internet Options/Connections. A similar situation is presented in zis. 140. Next, click the button Add VPN...

    Rice. 140.

    What is a VPN? Various computer companies often have the problem of combining several local networks that are located at a great distance from each other. In addition, there is the problem of connecting remote users and providing them with the necessary protection from unauthorized access. If a company uses its own or leased communication channels or telephone lines, then this is a rather expensive solution that only large and very successful companies can afford. That is why, in order to reduce the cost of data transmission, virtual network technology (English: Virtual Private Network VPN, virtual private network) was developed.

    The main feature of this technology is that a special channel is organized on top of the available network in a connection that has already been established. This channel allows for very high and reliable protection of the information that is transmitted through this channel (the so-called tunnel) from the subscriber to the provider. For these purposes it is used PPTP protocol(English: Point-to-Point Tunneling Protocol), a point-to-point tunnel protocol that allows a computer to establish a secure connection with a server by creating a special tunnel in a standard, unsecured network.

    Let's return to the VPN connection settings. By pressing the button Setting, should be entered Username, password And domain. The window shown in Fig. 141.

    All data must have been previously issued to the user by the network service provider. Next in the window Properties: Internet button should be pressed Network setup. A window will open Configuring local network settings(Fig. 142), in which you will need to check the box Use a proxy server for LAN connection. When finished, press the button OK.

    Next, you need to manually set/clarify the network settings. To do this, in the window at Start/Control Panel/Network and Internet/Network Connections(Fig. 143) you need to double click on the icon Local network connection.

    Rice. 141.


    Rice. 142.


    Rice. 143.

    This action will cause a window to appear in which you should click the Properties button. The Local Area Connection - Properties window will open, shown in Fig. 144.

    Rice. 144.

    Rice. 145.

    Next, from the list of components you need to select the option Internet Protocol Version 4 (TCP/IPv4) and press the button Properties. The window shown in Fig. 145 in which the options should be activated Obtain an IP address automatically And Obtain the DNS server address automatically.

    Each computer on the network must have its own unique IP address, determining its location on the Internet. IP addressing is a 32-bit digital system designed to identify networked computers on the Internet. Consists of four sets of numbers, where each number can range from 0 to 255, and is separated from the other values ​​by a dot, e.g.

    Domain name system looks like a phone book. The user finds the name of the person or the name of the organization with which he wants to contact - a telephone number is indicated next to it. Similarly, a computer accesses DNS (Domain Name System) using the name of another computer or domain, and the name server issues an 1P address corresponding to this name.

    A domain (area) name allows a person to work not with digital addresses of computers, but with familiar symbolic names (website addresses). The domain name is read from left to right from low-level domains to high-level domains (in order of increasing importance).

    For example, the domain name krf.ane.ru has three components called levels and separated by dots:

    ru- 1st (top) level domain name;

    ane.ru- 2nd level domain name (second level domain in the w zone); krf.ane.ru- 3rd level domain name (third level domain in the ane.ru zone). In terms of purpose, the following domain designations are accepted:

    Cell - for commercial sites;

    Info - for companies or sites providing information;

    Net - for telecommunications companies or companies doing business online;

    Org -- for non-profit organizations;

    Biz - zone for business sites as an alternative to the.cell zone;

    Ru, .de, .tk, .cn, .us, .ca, etc. - domains of different countries (geographical). Let's go back to the settings. Being in the window shown in Fig. 145, go to the tab Alternative configuration(see Fig. 146). Values ​​for IP address, DNS server, etc. issued by your network service provider.

    Next, in all open windows, press the button OK. The computer's network connection setup is complete, but you should restart the computer. After the reboot, double-click on the network connection name shortcut (it is specified during setup). The window shown in Fig. will open. 147.

    The username and password will be the default and will not need to be entered again. All you have to do is press the button Connection. After which the connection to the Internet is considered established and the user is taken to the home page (specified in the settings).

    Rice. 146.

    Test questions and assignments

    Rice. 147.

    • 1. What functions does a system administrator perform?
    • 2. List the administrator's steps to configure the operating environment.
    • 3. What is the network printing setup?
    • 4. Describe the administrator action known as network monitoring.
    • 5. What knowledge should a network administrator have in such an area as information security?
    • 6. What are the disadvantages of uncontrolled use of the Internet in organizations? What should a system provide to reduce such disadvantages?
    • 7. What software is used to control and manage Internet access? Give examples.
    • 8. List the tasks of differentiating access rights in the network.
    • 9. How does user authorization work?
    • 10. How does the locking system work to deny access to certain objects?
    • 11. Why is an access profile created?
    • 12. What are the three types of accounts? Tell us about each one.
    • 13. What steps do I need to take to create an account?
    • 14. What is the Windows 7 feature called parental controls?
    • 15. Tell us about such a protection option as a web filter.
    • 16. What needs to be done in order to connect a computer to the network?
    • 17. Show practically the sequence of actions required to connect a computer to the network.
    • 18. For what purposes is the PPTP protocol used? What is special about VPN technology?
    • 19. Explain what IP addressing is for.
    • 20. Tell us about the domain name system. Give examples of domain names. Explain what levels a domain name consists of.

    Today we will talk about how to install and configure a local server on your computer?!

    This is necessary so that you can develop and debug your scripts in PHP, since PHP is a programming language created for generating HTML pages that run on a web server and working with databases.

    Installing Apache server and related programs manually can be quite tedious. The fact is that you will have to deal with numerous configuration parameters for Apache, PHP and MySQL, which will never be useful to you again.

    In order to simplify the entire installation process as much as possible, the complex was created " Gentleman's kit for web developer", which contains the same distributions of Apache, PHP, MySQL and Perl, combined into a single archive, equipped with a convenient installer and configuration utilities for a specific machine.

    To download this set, follow the link http://www.denwer.ru/. This is the official website of Denver developers. Download the latest version of Denver from there.

    After you have downloaded the distribution, you need to run it. First, the archive will be unpacked into a temporary directory, and then the installer will automatically launch.

    Next, you will be asked in which directory you would like to install the complex (the default is C:\WebServer, You only need to press the "Enter" key to accept this choice). Absolutely all system components will be installed in the specified directory.

    After this, copying of the distribution files will begin, and at the end you will be asked how exactly you are going to start and stop the complex. You have two options:

    1. Automatically create a virtual disk when the machine boots, and do not disconnect it (the virtual disk) when the server is stopped. This is the most convenient mode. I recommend choosing him!
    2. Create a virtual disk only manually, using the complex start command (by clicking on the launch shortcut on the desktop). And, accordingly, disconnect the disk from the system when the server is stopped.

    Well, that's all. Installation is complete. Immediately click on the shortcut created by the installer "Startservers" on the desktop, and then wait until all console windows disappear.

    In order to check the operation of the local server, open your browser and type in the address: http://localhost. If everything went well, you will see the following window:

    So great! Now let's create a test site on the local server, which will have the address http://test.ru . To do this, open the directory where you installed the distribution (by default it is C:\WebServers). It contains 4 folders.

    So, remember, all your sites must be created in a folder "home"! To do this, open the “home” folder and create a directory in it with a name that matches the name of your future site (in our case it will be a directory with the name test.ru ). Now in the folder "test.ru" we will create another folder and call it " www ". It is in this folder that all the files of our site will be stored.

    After all folders have been created, you need to restart the server. To do this, use the shortcut "Restart servers" on the desktop.

    That's all there is to it. Now you can easily upload your files to your local server in the folder home/test.ru/www . And in order to check them, you need to type the address http://test.ru in your browser.

    That's all! Good luck!

    There are programs, or rather, assemblies of programs (platforms) that can emulate the operation of virtual hosting on an individual (home) computer. This means that by installing one of these platforms on your machine, you can work on creating a website without going online. Creating and testing a website on a local server can be approached in different ways. Some people cannot release a website without a local version, while others make websites directly on real hosting sites. But be that as it may, local server technologies exist, there are many software assemblies for developing websites on home machines, which means we will talk about them, talk about them, write articles and reviews on this site.

    To get into the topic of this section, let’s look at the structure of the global network from a home computer to any website. To visualize words, let's take a simple picture.

    As you can see, from the home machine to the site, which is on shared hosting, information passes through quite a lot of sections, the so-called network nodes. You can easily see all these nodes before any site on your computer by running a command, for example, ping.

    The general idea of ​​​​creating a website on a local computer

    The general idea of ​​creating a website on a local computer is simple. Instead of a long network from the computer to virtual hosting, local hosting is installed on the computer, and you, as a user, work not with remote hosting, but with hosting (server) installed on your actual disk.

    This is not surprising if you remember what virtual hosting or dedicated service is. In fact, these are also computers, only very “big”. They also install the software with which the hosting (server) is managed.

    Local server software builds

    To simplify a little, the main software assembly with which hosting can operate is an operating system, a web server, a database management system and a programming language. In such an assembly, various web servers (Apache, Nginx), various operating systems (Windows, Lunix), various DBMSs (MySQL, PostgreSQL, MariaBD, InnoDB) and various programming languages ​​(PHP, Perl) can be combined.

    For a local machine, software assemblies of local servers are labeled by the first letters of the programs included in the assembly. For example, LAMP is a Linux+Apache+MySQL+PHP build, and a WAMP build is Windows+ Apache+MySQL+PHP.

    In conclusion, I would like to note that if there are ready-made assemblies, then someone assembled them, which means you can install all the assembly programs separately on your computer and configure them to work together to emulate the work of hosting. There are also articles on this site about this.

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