OS_PPT

Introduction toNetworking : 

Introduction toNetworking Created By Saket Kr. Pathak M.Sc. NT & M Amity Institute of Information Technology

Introducing Network : 

Introducing Network Discussing the complex functionality of the OS to Networking in few slides is not an easy task to perform. The operating system provides an interface through which we can interact with the computer system. Some of the core services that an operating system offers are – Security Access to Storage Access to Printing Network Access As Concerned to Networking we should emphasis on the topics Security, Network Access and Access to Printing. The topic of networks is very broad and much of it falls well beyond the scope of our syllabus, but here we will try to get a look of as many as we can.

Our discussion starts with major components of Networking - : 

Our discussion starts with major components of Networking - Configuring Protocols:- Network Protocols are the languages that governs devices on the network to interact and provide systems that allow data to travel reliably on the network. Three primary networking protocols are - Transmission Control Protocol/Internet Protocol (TCP/IP) - Although the term TCP/IP is used as a single protocol, the TCP/IP suite of protocols actually comprises a large number of protocols. Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) - IPX/SPX is a protocol suite like TCP/IP, comprising numerous individual protocols. IPX/SPX was used primarily with Novell NetWare networks. AppleTalk and the NetBIOS Extended User Interface (NetBEUI) - AppleTalk is a protocol introduced to network Apple computers and NetBEUI is a non-routable protocol, and as such found its popularity on small localized networks.

Transmission Control Protocol/Internet Protocol (TCP/IP) - : 

Transmission Control Protocol/Internet Protocol (TCP/IP) - TCP/IP is now by far the networking protocol of maximum choice for Wide Area Networks as for Internet. The term TCP/IP is used as if it is describing a single protocol, the TCP/IP suite of protocols actually comprises a large number of protocols. TCP/IP uses software-configured addresses to identify the system on the network. There are two pieces of information that are required for addressing. These are the “IP Address” and the “Subnet Mask”. IP Address defines two things; The System and The Network to which it is attached. Subnet mask is used by the system to determine what parts of the IP address denote the system, and what parts refer to the network ID. The default gateway, a parameter that tells the system how to find a path from the network to which it is attached to remote networks. TCP/IP addresses can be assigned automatically via DHCP or manually.

Domain Name Server : 

Domain Name Server The Domain Name System (DNS) is a network service that allows easy-to-remember host names and to be translated into an IP address. A system to be able to use DNS it must be configured with the IP address of at least one DNS server. Servers are the systems that actually perform the domain name to IP address translation. As with the IP addressing information, the DNS server information can be supplied automatically via DHCP, or configured manually.

Windows Internet Naming Service (WINS) : 

Windows Internet Naming Service (WINS) Like DNS, WINS is designed for those of us who cannot remember those IP address numbers. WINS is designed to map computer (NetBIOS) names to IP addresses. WINS can resolve NetBIOS address to the computer’s name. If you have a computer with the address 192.168.23.45, it can resolve this address to the computer’s name, which might be something like secretary1, server1, or bobs-computer. NetBIOS - NetBIOS (Network Basic Input/Output System) is a program that allows applications on different computers to communicate within a local area network (Local Area Network).

Dynamic Host Configuration Protocol : 

Dynamic Host Configuration Protocol There are two ways in which a computer can get valid TCP/IP addressing information. One way is manually (statically) and Other is automatically (dynamically) via a System Software using protocol called the Dynamic Host Configuration Protocol (DHCP). Each time a computer attempts to connect to a network that uses DHCP for address assignment, it receives the IP address information from a DHCP server. IP addresses are leased to the computer for a specified period of time from a predefined range of IP addresses. If a system configured for DHCP cannot find a DHCP server, it will assign itself an IP address automatically from the reserved private range and process called as “Automatic Private IP Addressing (APIPA)”.

Configuring Client Options (using Softwares) : 

Configuring Client Options (using Softwares) Connecting to the network is the client software that makes it possible to use the services of other systems on the network. It is integrated into the OS and installed by default if you have a network card. Configuring client software (of System), you must specify the name of the workgroup in the network configuration. In Windows 2000, it’s done on the Network Identification tab of the System Properties dialog box (as follows), accessed from the System icon in the Control Panel.

Domain and Workgroup : 

Domain and Workgroup Windows OS–based networks can operate on one of two principles—Domain or Workgroup : - Domain - Domain networks are associated with a client/server network model. In a domain environment, a server is used to perform centralized authentication. To create a domain, you will need a network operating system on the server such as Windows 2000 Server or Windows 2003 Server. Workgroup – Workgroups are used with the peer-to-peer model. In a workgroup environment, administration is decentralized with each system being responsible for authentication.

Configuring Novell NetWare Clients : 

Configuring Novell NetWare Clients Novell provides client software, The Novell-supplied client has more features than the Microsoft client, but both require the same information in order to connect to and use network resources as :- User name - User name that we are supplied to log on to the network. Password - We should be provided with a password along with the user name. Tree - NetWare uses a concept known as trees to organize resources on the network. Because, it is necessary to specify which tree you want to connect to. Context - The context is the location within the tree where the user ID you want to log in as resides. Server - If a server name is not supplied, NetWare automatically selects the most appropriate server for you. The network administrator for information such as the tree name, the context, and the server. You will need to be able to connect to the network is a user name and password.

Verifying the Configuration : 

Verifying the Configuration A number of tools are used on a network to verify connectivity. Tools, we can use to troubleshoot TCP/IP-related connectivity as :- Ipconfig:- The Ipconfig command displays the TCP/IP configuration on Windows systems. Winipcfg - Winipcfg can report TCP/IP configuration information and can also be used to release and renew TCP/IP addresses obtained via DHCP. Ping - Perhaps the mostly widely used TCP/IP utility of all, the Ping utility tests connectivity between networked devices. Tracert - Tracert verifies the route to a remote system by reporting the status of every step on the journey. Nslookup:-The Nslookup utility can be used to troubleshoot the DNS configuration on a system. It is often used in advanced DNS troubleshooting.

Sharing and Setting Permissions : 

Sharing and Setting Permissions When we wish to allow other network users access to your files and folders, we can choose to share a “Specific Directory” or “File”. Sharing Print and File Services - Windows 2000 are configured to share resources as File And Printer Sharing must first be installed and then you must specify that you wish to make files and/or printers available to other users. Here “MSSQL7” folder is shared;

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File Sharing dialog box from a Windows is as;

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Accessing Shared Drives :- Accessing shared files or drives from another computer is the 2nd process to complete the step. Modern operating systems make it as easy as they can to access shared resources. Ways to access a shared drive on another system – Using My Computer :-

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Through Network Neighborhood - You can also map a drive by right-clicking Network Neighborhood and selecting Map Network Drive from the menu. Right-click My Network Places - In Windows 2000, you can map a drive by right-clicking My Network Places and selecting Map Network Drive from the menu. From the command line - If you want, you can map a network drive from the command prompt by using the Net Use command. This is useful if you want to map network drives through a batch file or logon script. Universal Naming Conventions :- When mapping to resources, a format known as the Universal Naming Convention (UNC) is used. The UNC was created to make a uniform method of referring to resources on the network. The basic format of a UNC is \\servername\sharename\subdirectory\subdirectory. In Windows networking, the NetBIOS name is used as the server element of the UNC and the resource you are accessing is the sharename.

Setting Permissions to Shared Resources : 

Setting Permissions to Shared Resources An important consideration when sharing resources is that of protecting them with permissions. There are four levels of security that you can apply to it. These permissions are – No Access - The No Access permission is a restrictive permission because it can take away all other permissions. Read - The Read permission enables a user to view and list all the files within the share, but not to make any changes to the files. Change - The Change permission allows a user to view, list, make changes to, and rename files within the share. Full Control - With the Full Control permission, a user can do anything to a share including renaming files, changing permissions on the share, and even renaming the share.

Configuring the Network Card : 

Configuring the Network Card The network card is an important hardware in terms of networking and provides the physical connection to the network. Computers within a network communicate from network card to network card over some type of network media, such as UTP cable. Almost every network card comes with a UTP connection. If you need some other type of connection like coaxial or fiber-optic, you will likely have to order it specially. Because of Plug and Play, this is now a simple task and often there is very little or no configuration required. To make sure that your network card has been correctly installed, you can check it in Device Manager. On a Windows 2000 system, configuration is performed through the Network And Dial-Up Connections folder in Control Panel.

Accessing the Internet : 

Accessing the Internet Here are some of the concepts and terminology that you will need to understand when supporting users who access the Internet. Internet Service Providers - ISPs are companies that specialize in providing Internet access to home and business users. ISPs can provide different types of Internet access including dial-up phone access, cable access, and digital subscriber line (DSL). TCP/IP - TCP/IP is suited to both wide area networks, such as the Internet, and local area networks. TCP/IP is actually more than a single protocol; it is a protocol suite, meaning that there are several individual protocols that operate under the TCP/IP banner. E-Mail - E-mail allows us to send and receive messages via the Internet. Most of the e-mail services we use today require the use of the Simple Mail Transfer Protocol (SMTP) to send mail and Post Office Protocol (POP) to receive mail. The current version of POP being used is version 3 (POP3). Internet Message Access Protocol or IMAP. IMAP is similar to POP in that it is used for retrieving e-mail and not sending it, which is still the responsibility of SMTP. POP actually transmits passwords in clear text, whereas IMAP does not.

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HTTP - Hypertext Transfer Protocol (HTTP) is used to establish a connection with a Web server and transmit HTML pages to the client browser. HTTP is a relatively simple protocol with a limited number of actions that it can perform. One of the drawbacks of HTTP is that requests and responses are sent in an unsecure manner. HTTPS - The Hypertext Transport Transfer Protocol Secure (HTTPS) protocol is used for accessing a secure Web server such as in online banking or other secure Internet transactions. Using HTTPS in the URL instead of HTTP directs the browser to establish a secure connection. Secure Sockets Layer - The Secure Sockets Layer (SSL) is the security system used by HTTPS. SSL works by encrypting information sent to and received from a remote host, making it unreadable by a third party.

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Telnet - Telnet is a protocol that allows a session to be opened on a remote host. You can use the remote host as if you are actually sitting at that system. Telnet is popular for accessing UNIX and Linux systems. FTP - File Transfer Protocol (FTP) is used to send and receive files from a remote computer, it can be used when downloading a program from the Internet. FTP has a simple set of commands that can be used with it, such as GET, which retrieves a file, and PUT, which sends a file. Domain Name System - In a TCP/IP network, computers identify themselves using IP addresses. An IP address is composed of four sets of numbers, each separated by periods.

Internet Connectivity Technologies : 

Internet Connectivity Technologies In this sections, we will look at some of the methods used to gain Internet access, including modem, cable, DSL, and satellite. These methods are discussed as follows :- Dial-up Networking - A dial-up connection to the Internet requires a modem and a special protocol called the Point-to-Point Protocol (PPP). DSL Networking - Digital subscriber line, or DSL, is an always-on Internet access method that uses a phone line to deliver high-speed Internet access. ISDN Networking - ISDN uses a special phone line and specialized equipment called terminal adapters to provide a connection. Cable - To get cable Internet access apart from connection you will also need a cable modem and a network card installed in your computer system. Satellite - Satellite Internet access is becoming popular in areas where other high-speed Internet access methods such as cable and DSL are not available. Wireless - Wireless Internet access is becoming increasingly popular in populated areas where a single wireless access point can provide service to a large number of people.

Dial-up Networking : 

Dial-up Networking A dial-up connection to the Internet requires a modem and a special protocol called the Point-to-Point Protocol (PPP). The many wizards used in modern operating systems make configuring a dial-up connection to the Internet fairly straightforward. To initiate the connection to the Internet using a dial-up connection, we need a few things, including :- An installed dial-up adapter The correct telephone number to dial the Internet connection The TCP/IP protocol installed The TCP/IP settings from the ISP A valid user name and password Configuring your dial-up connection depends on the operating system you are using. Anyone who has used a dial-up connection has no doubt at some point needed to troubleshoot it.

DSL Networking : 

DSL Networking Digital subscriber line, or DSL, is an always-on Internet access method that uses a phone line to deliver high-speed Internet access. It is a popular means of accessing the Internet but is only available in certain areas. The main factor limiting the availability of DSL is that you must be within a certain distance of the telephone company’s exchange in order to use it. The provider will either rent or sell you a DSL modem. This modem translates the signals from your computer into a format that can be sent over the phone line. When the company supplies the DSL modem they might also supply a network card to be installed in your PC. The card will most likely be a UTP network card and the DSL provider will give you a UTP cable to connect the card to the modem. It might be necessary to configure the browser so that it knows to use the DSL connection, which would actually be regarded as a LAN connection in many browser configurations.

ISDN Networking : 

ISDN Networking ISDN uses a special phone line and specialized equipment called terminal adapters to provide a connection. A terminal adapter can be either a card that is installed in a system, a dedicated external device, or a port on another piece of networking equipment such as a router. The function of the TA (Terminal Adapter) is to convert the signals so that they can be transmitted over the line. Although ISDN is a high-speed service, it is still considered a dial-up method because the connection is only established when there is traffic to be sent or received.

Cable : 

Cable Many cable television providers have now started to provide Internet access cable Internet is an always-on service that provides high-speed Internet access. To get cable Internet access apart from connection you will also need a cable modem and a network card installed in your computer system. The cable modem is a special device that translates the signal from the network card into a format that can be sent over the cable connection. Software configuration, the cable ISP will provide you with the necessary information for configuring e-mail clients and Web browsers. They will also provide you with information for configuring the addressing of the system. As with the other connectivity methods

Satellite : 

Satellite Satellite Internet access is becoming popular in areas where other high-speed Internet access methods such as cable and DSL are not available. In terms of configuration, satellite Internet access can be reasonably complex because there are a number of components, including dishes, special interface cards, cabling, and software. Two ways to access Internet:- one-way configuration, requests are sent over a modem to the provider and the replies are received over the much faster satellite link. two-way configuration, both the request and replies are sent over the satellite link. The advantage of the two-way system is that it is faster and does not require a modem and phone line. The downside is that the hardware and configuration for the link is even more complex. From a software perspective, the satellite ISP will provide the necessary information for the configurations.

Wireless : 

Wireless Wireless Internet access is increasing, because single wireless access point can provide service to a large number of people. To get access to a wireless Internet connection, you will need a wireless network card and an account with the ISP that is providing the service. An account with an ISP is not necessary because the service is provided free of charge by the establishment you are in. If you are experiencing a problem you might well have to troubleshoot it yourself. Apart from making sure that the wireless network card is functioning correctly, you should also ensure that your software configuration is correct for the environment you are in. In almost all cases this means that addressing information is obtained automatically.

Installing and Configuring Browsers : 

Installing and Configuring Browsers Browsers are programs that are used to view pages formatted in certain languages such as the Hypertext Markup Language (HTML) or the Extensible Markup Language (XML). These programs are often referred to as Web browsers because that’s what they are mostly used for—browsing the Web as Microsoft Internet Explorer, Netscape Navigator and Mozilla FireFox. Configuration information via DHCP, there is typically no configuration required to get a browser working and accessing pages from the Internet. Manually configured for TCP/IP, you might need to provide additional information, such as the addresses of DNS servers and perhaps even a default gateway, for the browsing Internet.

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Three areas of browser configuration :- Enabling/Disabling Script Support :- Scripts are small programs embedded within Web pages that can enhance functionality or appearance of a Web page. These same scripts can also contain malicious code that can perform actions on or from your PC. Browser programs commonly provide facilities that allow you to disable the running scripts and thus negate the risks presented by running scripts. We can configure support for scripts by selecting Tools, Internet Options, Security and then clicking the Custom Level button, to enable or disable script support as appropriate. Configuring Proxy Settings :- A proxy server is a system that processes Internet requests and responses on behalf of another system. Proxy servers can either be software running on a PC or dedicated hardware devices. In either case the configuration of the browser is the same. In Internet Explorer this configuration is accessed through the Tools menu, by choosing Internet Options, Connections, and LAN Settings.

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We will get the dialog Box as :-

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Configuring Security Settings :- Numerous threats exist that can at worst affect the configuration of your computer system and at least cause personal information to be “extracted” from your PC. In Internet Explorer these features are configured by choosing Tools, Internet Options, and then selecting the Security tab. There are four preset levels of security settings: Low, Medium, Medium High, and High. As the slider is moved between the levels, basic information is provided on-screen about that security level and what it does and does not allow. Each of the security levels can be further configured by clicking the Custom Level button. There are four zones: Internet, Local Intranet, Trusted Sites, and Restricted Sites. For the Local Intranet, Trusted Sites, and Restricted Sites zones, you can add sites that you wish to be included in that zone. Here we have the concerned window of Internet options -