Search
Related Links

 

 

Informative Articles

Dedicated Server Price Check by www.vipwh.com
The price of dedicated hosting services has really come down in the past couple of years. In fact, prices have dropped so much for the "budget dedicated server" market. While competitive conditions in both the hosting industry and the computer...

Provisioning/User Management System Upgrades: Part Two – Building Awareness And Building Approval
Somewhere in the world is a person who wants to see their provisioning/user management systems get a sorely needed upgrade. But they seem to be getting nowhere. The technical requirements are unarticulated. Key decisionmakers in the company...

Software Consulting
We are the india's best in giving quality work in time.We have developed many Software for Imaging service providers , Home builders, Ticket booking, Travelling agencies, Small ERP for Textile companies etc. So any one want's to give contract then...

Ten Percent Of Jimmy Stewart
Jimmy Stewart was seen one night in 1933 in New York performing on stage as a female impersonator by an MGM talent scout. He was signed to a contract to come to California to work for the prestigious studio. Studio Head Louis B. Mayer expressed...

The Xbox 360, a parental guide to this game console.
Xbox 360 is the next generation of the Microsoft Xbox. The Xbox 360 can easily be compared to a computer designed for gamming. Most of the games available work on most of the newer Microsoft platforms, (windows). XBOX 360 There...

 
Intranet


Introduction to Intranets

What exactly is an intranet? It's one of those terms that's more thrown around than understood, and has become more of a buzzword than a commonly understood idea. Simply put, an intranet is a private network with Internet technology used as the underlying architecture. An intranet is built using the Internet's TCP/IP protocols for communications. TCP/IP protocols can be run on many hardware platforms and cabling schemes. The underlying hardware is not what makes an intranet-it's the software protocols that matter.

Intranets can co-exist with other local area networking technology. In many companies, existing "legacy systems" including mainframes, Novell networks, minicomputers, and various databases, are being integrated into an intranet. A wide variety of tools allow this to happen. Common Gateway Interface (CGI) scripting is often used to access legacy databases from an intranet. The Java programming language can be used to access legacy databases as well.

With the enormous growth of the Internet, an increasing number of people in corporations use the Internet for communicating with the outside world, for gathering information, and for doing business. It didn't take long for people to recognize that the components that worked so well on the Internet could be equally valuable internally and that is why intranets are becoming so popular. Some corporations do not have TCP/IP networks, the protocol required to access the resources of the Internet. Creating an intranet in which all the information and resources can be used seamlessly has many benefits. TCP/IP-based networks make it easy for people to access the network remotely, such as from home or while traveling. Dialing into an intranet in this way is much like connecting to the Internet, except that you're connecting to a private network instead of to a public Internet provider. Interoperability between networks is another substantial bonus.

Security systems separate an intranet from the Internet. A company's intranet is protected by firewalls-hardware and software combinations that allow only certain people to access the intranet for specific purposes.

Intranets can be used for anything that existing networks are used for-and more. The ease of publishing information on the World Wide Web has made them popular places for posting corporate information such as company news or company procedures. Corporate databases with easy-to-build front-ends use the Web and programming languages such as Java.

Intranets allow people to work together more easily and more effectively. Software known as groupware is another important part of intranets. It allows people to collaborate on projects; to share information; to do videoconferencing; and to establish secure procedures for production work. Free server and client software and the multitude of services, like newsgroups, stimulated the Internet's growth. The consequence of that growth stimulated and fueled the growth of intranets. The ease with which information can be shared, and with which people can communicate with one another will continue to drive the building of intranets.

A Global View of an Intranet

An intranet is a private corporate or educational network that uses the Internet's TCP/IP protocols for its underlying transport. The protocols can run on a variety of network hardware, and can also co-exist with other network protocols, such as IPX. People from inside an intranet can get at the larger Internet resources, but those on the Internet cannot get into the intranet, which allows only restricted access from the Internet.


  • Videoconferencing is an important application that requires sending massive quantities of data. Intranets can be built using components that allow the extremely high bandwidths required for transferring such information.

  • Often an intranet is composed of a number of different networks inside a corporation that all communicate with one another via TCP/IP. These separate networks are often referred to as subnets.

  • Software that allows people to communicate with each other via e-mail and public message boards and to collaborate on work using workgroup software is among the most powerful intranet programs. Applications that allow different corporate departments to post information, and for people to fill out corporate forms, such as time sheets, and for tapping into corporate financial information are very popular.

  • Much of the software used on intranets is standard, off-the-shelf Internet software such as the Netscape Navigator and the Microsoft Explorer Web browsers. And customized programs are often built, using the Java programming language and CGI scripting.

  • Intranets can also be used to allow companies to do business-to-business transactions, such as ordering parts, sending invoices, and making payments. For extra security, these intranet-to-intranet transactions need never go out over the public Internet, but can travel over private leased lines instead.

  • Intranets are a powerful system for allowing a company to do business online, for example, to allow anyone on the Internet to order products. When someone orders a product on the Internet, information is sent in a secure manner from the public Internet to the company's intranet, where the order is processed and completed.

  • In order to protect sensitive corporate information, and to ensure that hackers don't damage computer systems and data, security barriers called firewalls protect an intranet from the Internet. Firewall technology uses a combination of routers, servers and other hardware and software to allow people on an intranet to use Internet resources, but blocks outsiders from getting into the intranet.

  • Many intranets have to connect to "legacy systems"-hardware and databases that were built before an intranet was constructed. Legacy systems often use older technology not based on the intranet's TPC/IP protocols. There are a variety of ways in which intranets can tie to legacy systems. A common way is to use CGI scripts to access the database information and pour that data into HTML formatted text, making it available to a Web browser.

  • Information sent across an intranet is sent to the proper destination by routers, which examine each TCP/IP packet for the IP address and determine the packet's destination. It then sends the packet to the next router closest to the destination. If the packet is to be delivered to an address on the same subnetwork of the intranet it was sent from, the packet may be able to be delivered directly without having to go through any other routers. If it is to be sent to another subnetwork on the intranet, it will be sent to another internal router address. If the packet is to be sent to a destination outside the intranet-in other words, to an Internet destination-the packet is sent to a router that connects to the Internet


How TCP/IP and IPX Work on Intranets

What distinguishes an intranet from any other kind of private network is that it is based on TCP/IP-the same protocols that apply to the Internet. TCP/IP refers to two protocols that work together to deliver data: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). When you send information across an intranet, the data is broken into small packets. The packets are sent independently through a series of switches called routers. Once all the packets arrive at their destination, they are recombined into their original form. The Transmission Control Protocol breaks the data into packets and recombines them on the receiving end. The Internet Protocol handles the routing of the data and makes sure it gets sent to the proper destination.


  1. In some companies, there may be a mix of TCP/IP-based intranets and networks based on other networking technology, such as NetWare. In that instance, the TCP/IP technology of an intranet can be used to send data between NetWare or other networks, using a technique called IP tunneling. In this instance, we'll look at data being sent from one NetWare network to another, via an intranet. NetWare networks use the IPX (Internet Packet Exchange) protocol as a way to deliver data-and TCP/IP networks can't recognize that protocol. To get around this, when an IPX packet is to be sent across an intranet, it is first encapsulated inside an IP packet by a NetWare server specifically for and dedicated to providing the IP transport mechanism for IPX packets.

  2. Data sent within an intranet must be broken up into packets of less than 1,500 characters each. TCP breaks the data into packets. As it creates each packet, it calculates and adds a checksum to the packet. The checksum is based on the byte values, that is, the precise amount of data in the packet.

  3. Each packet, along with the checksum, is put into separate IP wrappers or "envelopes." These wrappers contain information that details exactly where on the intranet-or the Internet-the data is to be sent. All of the wrappers for a given piece of data have the same addressing information so that they can all be sent to the same location for reassembly.

  4. The packets travel between networks by intranet routers. Routers examine all IP wrappers and look at their addresses. These routers determine the most efficient path for sending each packet to its final destination. Since the traffic load on an intranet often changes, the packets may be sent along different routes, and the packets may arrive out of order. If the router sees the address is one located inside the intranet, the packet may be sent directly to its destination, or it may instead be sent to another router. If the address is located out on the Internet, it will be sent to another router so it can be sent across the Internet.

  5. As the packets arrive at their destination, TCP calculates a checksum for each packet. It then compares this checksum with the checksum that has been sent in the packet. If the checksums don't match, TCP knows that the data in the packet has been corrupted during transmission. It then discards the packet and asks that the original packet be retransmitted.

  6. TCP includes the ability to check packets and to determine that all the packets have been received. When all the non-corrupt packets are received, TCP assembles them into their original, unified form. The header information of the packets relays the sequence of how to reassemble the packets.

  7. An intranet treats the IP packet as it would any other, and routes the packet to the receiving NetWare network. On the receiving NetWare network, a NetWare TCP/IP server decapsulates the IP packet-it discards the IP packet, and reads the original IPX packet. It can now use the IPX protocol to deliver the data to the proper destination.


How the OSI Model Works

A group called the International Standards Organization (ISO) has put together the Open Systems Interconnect (OSI) Reference Model, which is a model that describes seven layers of protocols for computer communications. These layers don't know or care what is on adjacent layers. Each layer, essentially, only sees the reciprocal layer on the other side. The sending application layer sees and talks to the application layer on the destination side. That conversation takes place irrespective of, for example, what structure exists at the physical layer, such as Ethernet or Token Ring. TCP combines the OSI model's application, presentation, and session layers into one which is also called the application layer.


  • The application layer refers to application interfaces, not programs like word processing. MHS (Message Handling Service) is such an interface and it operates at this level of the OSI model. Again, this segmentation and interface approach means that a variety of email programs can be used on an intranet so long as they conform to the MHS standard at this application interface level.

  • The presentation layer typically simply provides a standard interface between the application layer and the network layers. This type of segmentation allows for the great flexibility of the OSI model since applications can vary endlessly, but, as long as the results conform to this standard interface, the applications need not be concerned with any of the other layers.

  • The session layer allows for the communication between sender and destination. These conversations avoid confusion by speaking in turn. A token is passed to control and to indicate which side is allowed to speak. This layer executes transactions, like saving a file. If something prevents it from completing the save, the session layer, which has a record of the original state, returns to the original state rather than allowing a corrupt or incomplete transaction to occur.

  • The transport layer segments the data into acceptable packet sizes and is responsible for data integrity of packet segments. There are several levels of service that can be implemented at this layer, including segmenting and reassembly, error recovery, flow control, and others.

  • The IP wrapper is put around the packet at the network or Internet layer. The header includes the source and destination addresses, the sequence order, and other data necessary for correct routing and rebuilding at the destination.

  • The data-link layer frames the packets-for example, for use with the PPP (Point to Point). It also includes the logical link portion of the MAC sublayer of the IEEE 802.2, 802.3 and other standards.

  • Ethernet and Token Ring are the two most common physical layer protocols. They function at the MAC (Media Access Control) level and move the data over the cables based on the physical address on each NIC (Network Interface Card). The physical layer includes the physical components of the IEEE 802.3 and other specifications.


How TCP/IP Packets Are Processed

Protocols such as TCP/IP determine how computers communicate with each other over networks such as the Internet. These protocols work in concert with each other, and are layered on top of one another in what is commonly referred to as a protocol stack. Each layer of the protocol is designed to accomplish a specific purpose on both the sending and receiving computers. The TCP stack combines the application, presentation, and the session layers into a single layer also called the application layer. Other than that change, it follows the OSI model. The illustration below shows the wrapping process that occurs to transmit data.


  • The TCP application layer formats the data being sent so that the layer below it, the transport layer, can send the data. The TCP application layer performs the equivalent actions that the top three layers of OSI perform: the application, presentation, and session layers.

  • The next layer down is the transport layer, which is responsible for transferring the data, and ensures that the data sent and the data received are in fact the same data-in other words, that there have been no errors introduced during the sending of the data. TCP divides the data it gets from the application layer into segments. It attaches a header to each segment. The header contains information that will be used on the receiving end to ensure that the data hasn't been altered en route, and that the segments can be properly recombined into their original form.

  • The third layer prepares the data for delivery by putting them into IP datagrams, and determining the proper Internet address for those datagrams. The IP protocol works in the Internet layer, also called the network layer. It puts an IP wrapper with a header onto each segment. The IP header includes information such as the IP address of the sending and receiving computers, and the length of the datagram, and the sequence order of the datagram. The sequence order is added because the datagram could conceivably exceed the size allowed for network packets, and so would need to be broken into smaller packets. Including the sequence order will allow them to be recombined properly.

  • The Internet layer checks the IP header and checks to see whether the packet is a fragment. If it is, it puts together fragments back into the original datagram. It strips off the IP header, and then sends the datagram to the transport layer.

  • The transport layer looks at the remaining header to decide which application layer protocol-TCP or UDP-should get the data. Then the proper protocol strips off the header and sends the data to the receiving application.

  • The application layer gets the data and performs, in this case, an HTTP request.

  • The next layer down, the data link layer, uses protocols such as the Point-to-Point Protocol (PPP) to put the IP datagram into a frame. This is done by putting a header-the third header, after the TCP header and the IP header-and a footer around the IP datagram to fra-me it. Included in the frame header is a CRC check that checks for errors in the data as the data travels over the network.

  • The data-link layer ensures that the CRC for the frame is right, and that the data hasn't been altered while it was sent. It strips off the frame header and the CRC, and sends the frame to the Internet layer.

  • On the receiving computer, the packet travels through the stack, but in the opposite order from which the packet was created. In other words, it starts at the bottom layer, and moves its way up through the protocol stack. As it moves up, each layer strips off the header information that was added by the TCP/IP stack of the sending computer.

  • The final layer is the physical network layer, which specifies the physical characteristics of the network being used to send data. It describes the actual hardware standards, such as the Ethernet specification. The layer receives the frames from the data link layer, and translates the IP addresses there into the hardware addresses required for the specific network being used. Finally, the layer sends the frame over the network.

  • The physical network layer receives the packet. It translates the hardware address of the sender and receiver into IP addresses. Then it sends the frame up to the data link layer.


How Bridges Work

Bridges are hardware and software combinations that connect different parts of a single network, such as different sections of an intranet. They connect local area networks (LANs) to each other. They are generally not used, however, for connecting entire networks to each other, for example, for connecting an intranet to the Internet, or an intranet to an intranet, or to connect an entire subnetwork to an entire subnetwork. To do that, more sophisticated pieces of technology called routers are used.


  1. When there is a great amount of traffic on an Ethernet local area network, packets can collide with one another, reducing the efficiency of the network, and slowing down network traffic. Packets can collide because so much of the traffic is routed among all the workstations on the network.

  2. In order to cut down on the collision rate, a single LAN can be subdivided into two or more LANs. For example, a single LAN can be subdivided into several departmental LANs. Most of the traffic in each departmental LAN stays within the department LAN, and so it needn't travel through all the workstations on all the LANs on the network. In this way, collisions are reduced. Bridges are used to link the LANs. The only traffic that needs to travel across bridges is traffic bound for another LAN. Any traffic within the LAN need not travel across a bridge.

  3. Each packet of data on an intranet has more information in it than just the IP information. It also includes addressing information required for other underlying network architecture, such as for an Ethernet network. Bridges look at this outer network addressing information and deliver the packet to the proper address on a LAN

  4. Bridges consult a learning table that has the addresses of all the network nodes in it. If a bridge finds that a packet belongs on its own LAN, it keeps the packet inside the LAN. If it finds that the workstation is on another LAN, it forwards the packet. The bridge constantly updates the learning table as it monitors and routes traffic.

  5. Bridges can connect LANs in a variety of different ways. They can connect LANs using serial connections over traditional phone lines and modems, over ISDN lines, and over direct cable connections. CSU/DSU units are used to connect bridges to telephone lines for remote connectivity.

  6. Bridges and routers are sometimes combined into a single product called a brouter. A brouter handles both bridging and routing tasks. If the data needs to be sent only to another LAN on the network or subnetwork, it will act only as a bridge delivering the data based on the Ethernet address. If the destination is another network entirely, it will act as a router, examining the IP packets and routing the data based on the IP address.


How Intranet Routers Work

Just as routers direct traffic on the Internet, sending information to its proper destination, and routers on an intranet perform the same function. Routers-equipment that is a combination of hardware and software-can send the data to a computer on the same sub network inside the intranet, to another network on the intranet, or outside to the Internet. They do this by examining header information in IP packets, and then sending the data on its way. Typically, a router will send the packet to the next router closest to the final destination, which in turn sends it to an even closer router, and so on, until the data reaches its intended recipient.


  1. A router has


    input ports for receiving IP packets, and output ports for sending those packets toward their destination. When a packet comes to the input port, the router examines the packet header, and checks the destination in it against a routing table-a database that tells the router how to send packets to various destinations.

  2. Based on the information in the routing table, the packet is sent to a particular output port, which sends the packet to the next closest router to the packet's destination.

  3. If packets come to the input port more quickly than the router can process them, they are sent to a holding area called an input queue. The router then processes packets from the queue in the order they were received. If the number of packets received exceeds the capacity of the queue (called the length of the queue), packets may be lost. When this happens, the TCP protocol on the sending and receiving computers will have the packets re-sent.

  4. In a simple intranet that is a single, completely self-contained network, and in which there are no connections to any other network or the intranet, only minimal routing need be done, and so the routing table in the router is exceedingly simple with very few entries, and is constructed automatically by a program called ifconfig.

  5. In a slightly more complicated intranet which is composed of a number of TCP/IP-based networks, and connects to a limited number of TCP/IP-based networks, static routing will be required. In static routing, the routing table has specific ways of routing data to other networks. Only those pathways can be used. Intranet administrators can add routes to the routing table. Static routing is more flexible than minimal routing, but it can't change routes as network traffic changes, and so isn't suitable for many intranets.

  6. In more complex intranets, dynamic routing will be required. Dynamic routing is used to permit multiple routes for a packet to reach its final destination. Dynamic routing also allows routers to change the way they route information based on the amount of network traffic on some paths and routers. In dynamic routing, the routing table is called a dynamic routing table and changes as network conditions change. The tables are built dynamically by routing protocols, and so constantly change according to network traffic and conditions.

  7. There are two broad types of routing protocols: interior and exterior. Interior routing protocols are typically used on internal routers inside an intranet that routes traffic bound only for inside the intranet. A common interior routing protocol is the Routing Information Protocol (RIP). Exterior protocols are typically used for external routers on the Internet. AĘcommon exterior protocol is the Exterior Gateway Protocol (EGP).


Intranets come in different sizes. In a small company, an intranet can be composed of only a handful of computers. In a medium-sized business, it may include dozens or hundreds of computers. And in a large corporation, there may be thousands of computers spread across the globe, all connected to a single intranet. When intranets get large, they need to be subdivided into individual subnets or subnetworks.

To understand how subnetting works, you first need to understand IP addresses. Every IP address is a 32-bit numeric address that uniquely identifies a network and then a specific host on that network. The IP address is divided into two sections: the network section, called the netid, and the host section, called the hostid.

Each 32-bit IP address is handled differently, according to what class of network the address refers to. There are three main classes of network addresses: Class A, Class B, and Class C. In some classes, more of the 32-bit address space is devoted to the netid, while in others, more of the address space is devoted to the hostid. In a Class A network, the netid is composed of 8 bits, while the hostid is composed of 24 bits. In a Class B network, both the netid and the hostid are composed of 16 bits. In a Class C network, the netid is composed of 24 bits, while the hostid is composed of 8 bits. There's a simple way of knowing what class a network is in. If the first number of the IP address is less than 128, the network is a Class A address. If the first number is from 128 to 191, it's a Class B network. If the first number is from 192 to 223, it's a Class C network. Numbers above 223 are reserved for other purposes. The smaller the netid, the fewer number of networks that can b!

e subnetted, but the larger number of hosts on the network. A Class A rating is best for large networks while a Class C is best for small ones.

To create a subnet, the demarcation line on the IP address is moved between the netid and the hostid, to give the netid more bits to work with and to take away bits from the hostid. To do this, a special number called a subnet mask is used.

Subnetting is used when intranets grow over a certain size and they begin to have problems. One problem is management of host IP addresses-making sure that every computer on the network has a proper, up-to-date host address, and that old host addresses are put out of use until needed in the future. In a corporation spread out over several locations-or across the world-it's difficult, if not impossible, to have one person responsible for managing the host addresses at every location and department in the company.

Another problem has to do with a variety of hardware limitations of networks. Dissimilar networks may all be part of an intranet. An intranet may have some sections that are Ethernet, other sections that are Token Ring networks, and conceivably other sections that use different networking technologies altogether. There is no easy way for an intranet router to link these dissimilar networks together and route the information to the proper places.

Another set of problems has to do with the physical limitations of network technology. In some kinds of networks, there are some strict limitations on how far cables can extend in the network. In other words, you can't go over a certain distance of cabling without using repeaters or routers. A "thick" Ethernet cable, for example, can only be extended to 500 meters, while a "thin" Ethernet cable can only go to 300 meters. Routers can be used to link these cables together, so that an intranet can be extended well beyond those distances. But when that is done, each length of wire is essentially considered its own subnetwork.

Yet one more set of problems has to do with the volume of traffic that travels across an intranet. Often in a corporation, in a given department, most of the traffic is intradepartmental traffic-in other words, mail and other data that people within a department send to each another. The volume of traffic outside to other departments is considerably less. What's called for is a way to confine intradepartmental traffic inside the departments, to cut down on the amount of data that needs to be routed and managed across the entire intranet.

Subnetting solves all these problems and more. When an intranet is divided into subnets, one central administrator doesn't have to manage every aspect of the entire intranet. Instead, each subnet can take care of its own administration. That means smaller organizations within the larger organization can take care of problems such as address management and a variety of troubleshooting chores. If an intranet is subnetted by divisions or departments, it means that each division or department can guide the development of its own network, while adhering to general intranet architecture. Doing this allows departments or divisions more freedom to use technology to pursue their business goals.

Subnets also get around problems that arise when an intranet has within it different kinds of network architecture, such as Ethernet and Token Ring technologies. Normally-if there is no subnetting-a router can't link these different networks together because they don't have their own addresses. However, if each of the different networks is its own subnet-and so has its own network address-routers can then link them together and properly route intranet traffic.

Subnetting can also cut down on the traffic traveling across the intranet and its routers. Since much network traffic may be confined within departments, having each department be its own subnet means that all that traffic need never cross an intranet router and cross the intranet-it will stay within its own subnet.

Subnetting can also increase the security on an intranet. If the payroll department, for example, were on its own subnet, then much of its traffic would not have to travel across an intranet. Having its data traveling across the intranet could mean that someone could conceivably hack into the data to read it. Confining the data to its own subnet makes that much less likely to happen.

Dividing an intranet into subnets can also make the entire intranet more stable. If an intranet is divided in this way, then if one subnet goes down or is often unstable, it won't affect the rest of the intranet.

This all may sound rather confusing. To see how it's done, let's take a look at a network, and see how to use the IP address to create subnets. Let's say we have a Class B network. That network is assigned the address of 130.97.0.0. When a network is given an address, it is assigned the netid numbers-in this case, the 130.97-and it can assign the host numbers (in this case, 0.0) in any way that it chooses.

The 130.97.0.0 network is a single intranet. It's getting too large to manage, though, and we've decided to divide it into two subnets. What we do is fairly straightforward. We take a number from the hostid field and use it to identify each of the subnets. So one subnet gets the address 130.97.1.0, and the other gets the address 130.97.2.0. Individual machines on the first subnet get addresses of 130.97.1.1, 130.97.1.2, and so on. Individual machines on the second subnet get addresses of 130.97.2.1, 130.97.2.2 and so on.

Sounds simple. But we have a problem. The Internet doesn't recognize 130.97.1.0 and 130.97.2.0 as separate networks. It treats them both as 130.97.0.0 since the "1" and "2" that we're using as a netid is only known to the Internet as a hostid. So our intranet router will not be able to route incoming traffic to the proper network.

To solve the problem, a subnet mask is used. A subnet mask is a 32-bit number in IP form used by intranet routers and hosts that will help routers understand how to route information to the proper subnet. To the outside Internet, there is still only one network, but the subnet mask allows routers inside the intranet to send traffic to the proper host.

A subnet mask is a number such as 255.255.255.0 (the built-in default for Class C addresses; the Class B default is 255.255.0.0 and the default for Class A is 255.0.0.0). A router takes the subnet mask and applies that number against the IP number of incoming mail to the network by using it to perform a calculation. Based on the resulting IP number, it will route mail to the proper subnet, and then to a particular computer on the subnet. For consistency, everyone in a particular intranet will use the same subnet mask.

Subnetting an Intranet

When intranets are over a certain size, or are spread over several geographical locations, it becomes difficult to manage them as a single network. To solve the problem, the single intranet can be subdivided into several subnets, subsections of an intranet that make them easier to manage. To the outside world, the intranet still looks as if it's a single network.


  1. If you're building an intranet and want it to be connected to the Internet, you'll need a unique IP address for your intranet network, which the InterNIC Registration Services will handle. There are three classes of intranet you can have: Class A, Class B, or Class C. Generally, a Class A rating is best for the largest networks, while a Class C is best for the smallest. A Class A network can be composed of 127 networks, and a total of 16,777,214 nodes on the network. A Class B network can be composed of 16,383 networks, and a total of 65,534 nodes. A Class C network can be composed of 2,097,151 networks, and 254 nodes.

  2. When an intranet is assigned an address, it is assigned the first two IP numbers of the Internet numeric address (called the netid field) and the remaining two numbers (called the hostid field) are left blank, so that the intranet itself can assign them, such as 147.106.0.0. The hostid field consists of a number for a subnet and a host number.

  3. When an intranet is connected to the Internet, a router handles the job of sending packets into the intranet from the Internet. In our example, all incoming mail and data comes to a router for a network with the netid of 147.106.0.0.

  4. When intranets grow-for example, if there is a department located in another building, city, or country-there needs to be some way to manage network traffic. It may be impractical and physically impossible to route all the data necessary among many different computers spread across a building or the world. A second network-called a subnetwork or subnet-needs to be created.

  5. In order to have a router handle all incoming traffic for a subnetted intranet, the first byte of the hostid field is used. The bits that are used to distinguish among subnets are called subnet numbers. In our example, there are two subnets on the intranet. To the outside world, there appears to be only one network.

  6. Each computer on each subnet gets its own IP address, as in a normal intranet. The combination of the netid field, the subnet number, and then finally a host number, forms the IP address.

  7. The router must be informed that the hostid field in subnets must be treated differently than non-subnetted hostid fields, otherwise it won't be able to properly route data. In order to do this, a subnet mask is used. A subnet mask is a 32-bit number such as 255.255.0.0 that is used in concert with the numbers in the hostid field. When a calculation is performed using the subnet mask and the IP address, the router knows where to route the mail. The subnet mask is put in people's network configuration files.


Overview of an Intranet Security System

Any intranet is vulnerable to attack by people intent on destruction or on stealing corporate data. The open nature of the Internet and TCP/IP protocols expose a corporation to attack. Intranets require a variety of security measures, including hardware and software combinations that provide control of traffic; encryption and passwords to validate users; and software tools to prevent and cure viruses, block objectionable sites, and monitor traffic.


  • The generic term for a line of defense against intruders is a firewall. A firewall is a hardware/software combination that controls the type of services allowed to or from the intranet.

  • Proxy servers are another common tool used in building a firewall. A proxy server allows system administrators to track all traffic coming in and out of an intranet.

  • A bastion server firewall is configured to withstand and prevent unauthorized access or services. It is typically segmented from the rest of the intranet in its own subnet or perimeter network. In this way, if the server is broken into, the rest of the intranet won't be compromised.

  • Server-based virus-checking software can check every file coming into the intranet to make sure that it's virus-free.

  • Authentication systems are an important part of any intranet security scheme. Authentication systems are used to ensure that anyone trying to log into the intranet or any of its resources is the person they claim to be. Authentication systems typically use user names, passwords, and encryption systems.

  • Server-based site-blocking software can bar people on an intranet from getting objectionable material. Monitoring software tracks where people have gone and what services they have used, such as HTTP for Web access.

  • One way of ensuring that the wrong people or erroneous data can't get into the intranet is to use a filtering router. This is a special kind of router that examines the IP address and header information in every packet coming into the network, and allows in only those packets that have addresses or other data, like e-mail, that the system administrator has decided should be allowed into the intranet.


All intranets are vulnerable to attack. Their underlying TCP/IP architecture is identical to that of the Internet. Since the Internet was built for maximum openness and communication, there are countless techniques that can be used to attack intranets. Attacks can involve the theft of vital company information and even cash. Attacks can destroy or deny a company's computing resources and services. Attackers can break in or pose as a company employee to use the company's intranet resources.

Firewalls are hardware and software combinations that block intruders from access to an intranet while still allowing people on the intranet to access the resources of the Internet. Depending on how secure a site needs to be, and on how much time, money, and resources can be spent on a firewall, there are many kinds that can be built. Most of them, though, are built using only a few elements. Servers and routers are the primary components of firewalls.

Most firewalls use some kind of packet filtering. In packet filtering, a screening router or filtering router looks at every packet of data traveling between an intranet and the Internet.

Proxy servers on an intranet are used when someone from the intranet wants to access a server on the Internet. A request from the user's computer is sent to the proxy server instead of directly to the Internet. The proxy server contacts the server on the Internet, receives the information from the Internet, and then sends the information to the requester on the intranet. By acting as a go-between like this, proxy servers can filter traffic and maintain security as well as log all traffic between the Internet and the network.

Bastion hosts are heavily fortified servers that handle all incoming requests from the Internet, such as FTP requests. A single bastion host handling incoming requests makes it easier to maintain security and track attacks. In the event of a break in, only that single host has been compromised, instead of the entire network. In some firewalls, multiple bastion hosts can be used, one for each different kind of intranet service request.

How Firewalls Work

Firewalls protect intranets from any attacks launched against them from the Internet. They are designed to protect an intranet from unauthorized access to corporate information, and damaging or denying computer resources and services. They are also designed to stop people on the intranet from accessing Internet services that can be dangerous, such as FTP.


  1. Intranet computers are allowed access to the Internet only after passing through a firewall. Requests have to pass through an internal screening router, also called an internal filtering routeror choke router. This router prevents packet traffic from being sniffed remotely. A choke router examines all pack-ets for information such as the source and destination of the packet.

  2. The router compares the information it finds to rules in a filtering table, and passes or drops the packets based on those rules. For example, some services, such as rlogin, may not be allowed to run. The router also might not allow any packets to be sent to specific suspicious Internet locations. A router can also block every packet traveling between the Internet and the internal network, except for e-mail. System administrators set the rules for determining which packets to allow in and which to block.

  3. When an intranet is protected by a firewall, the usual internal intranet services are available-such as e-mail, access to corporate databases and Web services, and the use of groupware.

  4. Screened subnet firewalls have one more way to protect the intranet-an exterior screening router, also called an exterior filtering router or an access router. This router screens packets between the Internet and the perimeter network using the same kind of technology that the interior screening router uses. It can screen packets based on the same rules that apply to the internal screening router and can protect the network even if the internal router fails. It also, however, may have additional rules for screening packets specifically designed to protect the bastion host.

  5. As a way to further protect an intranet from attack, the bastion host is placed in a perimeter network-a subnet-inside the firewall. If the bastion host was on the intranet instead of a perimeter network and was broken into, the intruder could gain access to the intranet.

  6. A bastion host is the main point of contact for connections coming in from the Internet for all services such as e-mail, FTP access, and any other data and requests. The bastion host services all those requests-people on the intranet contact only this one server, and they don't directly contact any other intranet servers. In this way, intranet servers are protected from attack.


Pawan Bangar, technical Director, Birbals, India.


www.birbals.com


www.seobirbals.com


www.hbirbals.com


www.ebirbals.com


pawan@ebirbals.com


 

Tom's Hardware
: Tom's Hardware Guide is the Internet's premiere resource for hardware news and reviews.
www.tomshardware.com
 
HardwareCentral - Your source for in-depth computer hardware info.
HardwareCentral is the #1 Hardware Information Resource on the 'Net. Featuring over 600 pages of Hardware information, including advice on System ...
www.hardwarecentral.com
 
Apple - Hardware
Find your favorite Mac, iPod and other Apple accessories.
www.apple.com
 
Ace Hardware
Nationwide (United States) hardware and home improvement retailer. Includes products, dealer locator and corporate information.
www.acehardware.com
 
Computer hardware - Wikipedia, the free encyclopedia
The hardware of a computer is infrequently changed, in comparison with software and ... Personal computers, the computer hardware familiar to most people, ...
en.wikipedia.org
 
Hardware - Wikipedia, the free encyclopedia
Hardware is the general term that is used to describe physical artifacts of a technology. ... In a looser sense, hardware can be major military equipment, ...
en.wikipedia.org
 
Open Directory - Computers: Hardware
Hardware Central - Computing-centric community providing vital information, support, tools and interaction facilities for power computer users and ...
dmoz.org
 
Microsoft Hardware – Home Page
Learn about Microsoft mice, keyboards, desktop sets, webcams, media center peripherals, gaming products, fingerprint readers and presentation tools.
www.microsoft.com
 
AnandTech: your source for hardware analysis and news
Independent hands-on reviews of computer hardware such as motherboards, graphic cards, and CPUs.
www.anandtech.com
 
hardware.com - Routers, switches, firewalls, servers, memory ...
Supplier of new and refurbished networking hardware and approved and compatible network accessories. Located in the United Kingdom.
www.hardware.com
 
Slashdot: News for nerds, stuff that matters
From the article: "Although the news caused barely a ripple of reaction in the audience of software and hardware engineers, there are industry analysts who ...
hardware.slashdot.org
 
InformationWeek HardwareTech Center
Our hardware coverage ranges from mobile computers and PDAs to servers and supercomputers, and the infrastructure issues enterprises deal with every day. ...
www.informationweek.com
 
What is hardware? - A Word Definition From the Webopedia Computer ...
This page describes the term hardware and lists other pages on the Web where you can find additional information.
www.webopedia.com
 
Google Directory - Computers > Hardware
Hardware Central - http://www.hardwarecentral.com/ Computing-centric community providing vital information, support, tools and interaction facilities for ...
www.google.com
 
Gifts: Unique Gifts & Gift Ideas at Restoration Hardware
At Restoration Hardware, you'll explore an exceptional world of high quality unique gifts. Browse our products to find gift ideas & more at Restoration ...
www.restorationhardware.com
 
HwB: The Hardware Book
HwB provides you with circuits, pinouts, cable/adapter descriptions and other technical information.
www.hardwarebook.net
 
Reg Hardware: Product News and Gadget Reviews from The Register
More Gadgets Stuff. 5th December 2006 12:09 GMT. Author: Reg Hardware ... 27th November 2006 15:31 GMT. Author: The Hardware Widow ...
www.reghardware.co.uk
 
red hat hardware compatibility lists
hardware.redhat.com/ - Similar pages
 
TrueValue.com
Here's our tip to hang strands of lights with ease. Jeanenne & Jim Tucker Plantation True Value Hardware Richmond, TX ...
www.truevalue.com
 
A complete illustrated Guide to the PC Hardware
A complete illustrated Guide to the PC Hardware, Logic and Architecture. 500 easy-read articles about the modern PC. Understand the basic architecture of ...
www.karbosguide.com
 
 

 

Content Menu
  • 10 easy steps to speed up your computer without upgrading

  • 1 simple step towards improved customer satisfaction for web hosts

  • 4 ways to get your opt in subscribers to trust you quickly

  • 5 desktop computer hardware myths exposed

  • 5 minute guide to video editing for beginners

  • 5 simple tips to prevent ms access database corruption

  • 5 steps to choosing a great host

  • 5 sure fire tips for buying a new computer

  • 5 ways to give your web site a big company look and feel

  • 7 barebones computer buying tips

  • 7 reasons not to take your laptop on holiday

  • 7 simple reasons why you need a network security camera for your home

  • 7 steps to cleaning the laser toner from your laser printer

  • adult web hosting the all you need to know

  • advancement in computer technology

  • advantages of buying used servers

  • all about the new scmad certification exam

  • alternatives to tape backup

  • another title by atari released on starforce protected dvds

  • anti spam at the enterprise level

  • are they watching you online

  • are you waiting for microsoft longhorn

  • are you well protected

  • a beginner guide to web hosting

  • a brief history of tablet pcs

  • a business center in your hotel curse or blessing

  • a computer and internet glossary

  • a hacker inside your computer

  • a review of refurbished toshiba laptops

  • a simple guide to web hosting

  • backing up your stuff part 2 a solution

  • backing up your stuff part 3 software

  • backing up your stuff part 7 where is it 3

  • basic computer maintenance

  • basic diagnosis guidelines for your pc

  • basic problem in a pc

  • beginners guide to pc video editing

  • beware of spyware

  • be informed when you purchase a computer

  • be prepared in the event computer disaster strikes

  • bios term

  • boost your websites search engine rankings in 5 simple steps

  • boot camp troubleshooting hardware bootup problems

  • build your first computer from hardware scratches

  • build your own computer or buy

  • burning bridges is bad but firewalls are good

  • buying a computer ask these 3 questions

  • buying a used laptop computer

  • buying e books on e bay e bay the one stop e book shop

  • cad

  • can i hear your web site

  • can you restore data from your backup

  • carnivore

  • chicken little entrepreneurs

  • choose your email marketing software wisely

  • choosing a web host

  • choosing the right host for your site

  • choosing the wrong server will literally make or break you

  • cisco ccna ccnp home lab why you need an isdn simulator

  • cisco certification suggested topologies for your ccna ccnp home lab

  • clustering solutions and zero downtime hosting pitfalls

  • colors for your website

  • combat computer spyware an antispyware program isnt enough

  • computer buying advice for novices

  • computer case modding

  • computer consulting 101 hiring tips part 1 of 2

  • computer data backup data backup solution will give you a peace of mind

  • computer hardware preventive maintenance software

  • computer hygiene take out the trash

  • computer network designing

  • computer network installation

  • computer rentals the best classroom computer training solution

  • computer sos inc release of upgraded league management software package

  • computer tips that help small businesses operate profitably

  • congress taking a fresh look at online sales taxes

  • coping with a serious data loss from your computer hard drive

  • credit card processing on the internet

  • crying for help online

  • cure for illegal operations sydrome

  • custom error pages

  • cyber warfare

  • data backups one key to business survival

  • data backup for beginners

  • data backup solution why you need a backup plan in place part 1

  • data backup solution why you need a backup plan in place part 2

  • death before birth the life cycle of a search engine

  • declarative programming strategies for solving software problems

  • dedicated co location inside a securely monitored bank vault at lasvegas net

  • dedicated server price check by www vipwh com

  • dedicated server vs co location web hosting by www vipwh com

  • dedicated web hosting the executive summary

  • defining olap solutions and data warehouse design

  • denial of service attack

  • desktop security software risks part 1

  • desktop security software risks part 2

  • device driver basics

  • dhcp

  • did i hear you say mama help me i lost my websites

  • different categories of computer games

  • digital dispatch is the internet safe

  • digital rights management

  • does it worth to backup emails from clients like outlook express

  • dont allow hackers to take out money from your bank account

  • do we really need the internet

  • do you need a web site monitoring service

  • d bust your computer part 5

  • easy to execute

  • edit able art

  • email anti spam and virus protection for businesses there is hope

  • esecurity

  • esolution software developments

  • exchange disaster recovery with sanrad v switch planning guide

  • finally an understandable introduction to computers

  • finding a physical phone tap

  • finding a quality and affordable web host

  • finding the right performance optimizer

  • find the host with the most

  • firewalls what they are and why you must have one

  • firewall protection does your firewall do this

  • five things to try if you are having wireless troubles

  • free detailed pc analysis

  • freight broker software

  • freight software

  • getting help using mailing lists

  • getting more bang for the storage buck

  • getting patched with windows service pack

  • get familiar with msdos sys

  • get your multimedia cbt educational cd educational software

  • got virus

  • got virus your data is not lost forever

  • great plains dexterity history and programming overview

  • guarding against email scams

  • hacking in cyberspace

  • hard drive crash the essential data recovery report

  • hard drive selection

  • helpdesk asset management software top questions to ask before you buy

  • help me choose linux vs windows web hosting

  • history of linux

  • home audio recording for everyone

  • how a security specialist fell victim to attack

  • how do wireless networks work

  • how multiple server hosting impacts your websites uptime

  • how multiple server hosting impacts your web sites uptime

  • how to become an information superstar

  • how to become a dot com millionaire part 2

  • how to buy a laptop buyers guide notes

  • how to change upgrade or remove and ide hard drive

  • how to choose a reliable web host

  • how to consider a web host

  • how to fight cyberterrorism

  • how to get the case off your pc

  • how to get the computer you want without spending a fortune

  • how to install cable dls and dialup modems fast

  • how to never pay a hotel phone bill again

  • how to overclock a processor

  • how to prevent spyware attacking your computer

  • how to quickly fix nagging dvd drive problems

  • how to really backup the windows registry

  • how to really create a startup disk

  • how to really install a modem

  • how to re record other video files

  • how to rip shrink a full dvd movie backup a dvd dvd shrink dvd decrypter tutorial

  • how to shop online safely

  • how to speed up your pc

  • how to start a tech support business

  • how to tame your mouse

  • how to tell you are infected with spyware ad ware or viruses

  • how to troubleshoot dvd drives fast

  • how to upgrade your pc

  • hpc systems inc announces first 8 way processor amd opterone server

  • ibm lotus domino or microsoft exchange

  • ie firefox opera netscape mozilla and more

  • if you had problems in the past with a computer virus then youll want to know how easy it is to setup firewall protection

  • image conversion in computers

  • implementation of asp application services provision

  • implementing a secure password policy

  • importance of backups

  • important steps to protect your computer from hurricanes

  • improve pc performance 6 tips you must know

  • improving sql performance

  • im guilty until proven innocent

  • index

  • inkjet printer tips to select proper printer

  • internet communication

  • internet faxing service review

  • internet security backups

  • intranet

  • intranet portal business case roi

  • introduction to dedicated servers

  • introduction to visual basic

  • invest wisely when buying a laptop

  • iscsi vs fc for meeting mission critical requirements

  • is it still good to share

  • is my pc vulnerable on the internet

  • is that pc still worth keeping

  • is voice over ip right for me

  • is your computer infected with spyware

  • is your laptop or home computer wireless enabled

  • its war i tell you

  • jungo joins texas instruments third party dsp network to provide software hardware connectivity solutions

  • keeping the windows registry operational

  • keep a diary of your computer

  • know linux

  • lay out tips

  • linux display settings

  • linux for home users

  • linux web hosting

  • linux web hosting the all you need to know

  • longer term play

  • lost your usb flash dont panic

  • low budget horror stories

  • managed and unmanaged dedicated hosting

  • managed hosting whats it all about

  • managed vs unmanaged dedicated hosting by www vipwh com

  • mcse 70 290 certification primer

  • memory bandwidth vs latency timings

  • microsoft class action settlement in minnesota submitting a claim

  • microsoft great plains if you are orphan client what to do and faq

  • microsoft sql 2000 disaster recovery with sanrad v switch planning guide

  • microworld antivirus mwav toolkit utility

  • more computer consulting 101 hiring tips part 2 of 2

  • more dvd burning tips

  • more free tools increase security for your pc

  • mpeg encoder for burning dvds

  • ms sql mysql a case study

  • music cd r vs data cd r is there a difference

  • need of document management system dms

  • network performance management the 6 pillars of network management system

  • network wiring standards

  • net words by nick usborne a book review

  • new olap concept

  • new software suite improves productivity and slashes costs for small and medium size businesses

  • no computer sound

  • no operating system

  • on reconditioned or refurbished notebooks

  • o software livre realmente nos libertar  dos custos

  • passwords or pass phrase protecting your intellectual property

  • pc gaming video meeting the demands

  • pc owners the largest criminal gang ever

  • pdf faster delivery lowered costs

  • physical topology of a network refers to the configuration of cables computers

  • plug and play resource allocation

  • plug ins and xtensions indesign indexers quarkxpress catalogers photoshop fixers

  • podcasting trend

  • printing troubleshooting guide

  • protecting your identity on the internet

  • protect your computer and internet privacy

  • protect your pc from viruses worms trojans

  • provisioning user management system upgrades part one ten reasons why not to do an upgrade or the gentle art of not doing when good systems go bad

  • provisioning user management system upgrades part two building awareness and building approval

  • p c security housekeeping basics

  • raid disk recovery

  • refurbished computers on the internet

  • registry cleaners why do you need one

  • remote deployment of surveillance spyware software

  • remove rogue desktop icons created by spyware

  • report on growth and economic impact of the it industry

  • reseller hosting explained

  • reseller web hosting

  • review on paint shop pro 7 solutions book

  • reviving old computer games

  • rotator

  • save your software

  • screenshots vista windows

  • script kiddies ii an advice to parents

  • secrets to spyproofing your computer in four easy steps

  • security firewalls

  • security in todays world

  • seecrets on security a gentle introduction on cryptography part 2

  • seecrets on security a gentle introduction to cryptography

  • see how to revive a dead computer

  • see how to troubleshoot pc mouse problems fast

  • setting up an internet connection

  • setting up a linux modem

  • setting up a tape backup strategy for your business

  • should i use windows update

  • should you build your own pc

  • should you upgrade your hardware pc

  • simplenet director of marketing

  • small wonders single board computers

  • software consulting

  • software for hard jobs contractors have some powerful tools in todays software

  • software piracy global increase

  • software that takes care of other software

  • special rules for selling software on ebay

  • spyware versus adware the difference impacts your privacy

  • spyware what it is and how to combat it

  • starforce protection solutions at games convention 2004

  • static discharge causes flaky damage

  • step by step troubleshooting ram

  • sticky sites rule the internet

  • streaming audio made easy

  • surge protector a simple mechanism description

  • system downtime

  • system restore the big undo

  • talking rugged notebook

  • ten great careers for computer geeks

  • ten percent of jimmy stewart

  • that darned old internet gateway

  • the art of display

  • the basics of hosting

  • the complete guide to spotting computer spies recording devices

  • the cost of spyware on your computer

  • the cycle of windows life

  • the database design alalysis business perspective

  • the economics of spam

  • the essential data recovery report

  • the hidden tiger

  • the host with the most

  • the important steps to protect your kids on the internet

  • the metaphors of the net

  • the metaphors of the net part ii

  • the metaphors of the net part iii

  • the metaphors of the net part iv

  • the never ending spywarestory

  • the never ending spyware story

  • the problems with passwords

  • the pros cons of hosting the site yourself

  • the seamless internet

  • the secret computer virus that is virtually undetectable

  • the security risks and ways to decrease vulnerabilities in a 802 11b wireless environment

  • the seven deadly habits of a dba and how to cure them

  • the spyware who loved me

  • the trials and tribulations of a confused computer

  • the two most important things you need to run a wildly successful web site

  • the universal serial bus

  • the worst case scenario how to protect your data

  • the xbox 360 a parental guide to this game console

  • things newbies need to know

  • tips about low cost web hosting services

  • tips for finding the perfect portable mp3 player

  • tips for turning cd duplication into a profitable side business

  • tips on finding a web host

  • tips to select proper hard drive

  • tips to select proper motherboard

  • top 7 reasons you should back up your data online

  • transportation management software

  • transportation software

  • trouble shooting mouse problems

  • tucsons nextwest inc announces partnership with dialresults inc

  • two enter internet battle

  • ultimate checklist on how to revive a dead computer

  • understanding the components of a home network

  • understanding the software layers of a computer

  • unleash the dragon inside your computer

  • unlimited bandwidth in web hosting

  • unlimited wealth creation through reseller hosting

  • unrelated inventiions catering for the uncommon denominator

  • ups technologies explained

  • usb hubs and ports explained

  • using a bluetooth headset with your pc

  • using sanrad v switch as the vss hardware provider for windows backups

  • video game rental pros of renting video games

  • virtual hosting the affordable hosting solution for reseller web hosting companies

  • virtual hosting vs dedicated hosting

  • virtual it anyone

  • virtual private server web hosting

  • voice over internet protocol

  • voip questions and answers

  • wealth for free

  • webfarms the only way to host

  • website and network stress monitoring

  • web hosting guide for beginner

  • web hosting reviews can you trust them

  • web hosting server what to look for

  • web hosting web development for beginners

  • web hosting web development understand and create great websites

  • web hosts the basics

  • welcome to the world of knoppix

  • we know why you havent decided yet to purchase a security product

  • whats in a name

  • whats your right photo shade

  • what are international isp global isp

  • what does your john hancock look like

  • what do customers really want

  • what is a server

  • what is computer programming anyway

  • what is data recovery a brief introduction

  • what is tcp ip

  • what is vsat broadband

  • what makes a good web hosting provider

  • what to consider when taking your cmms mobile

  • what to do once you are infected with spyware ad ware or viruses

  • what to look for in an assembled pc

  • when to rent a laptop computer

  • which web host is right for you

  • which web host should i choose to host my business site

  • which web server

  • why build your own gaming computer

  • why network documentation is so important

  • why slow access to your site is killing your business

  • why your online advertising traffic leaves as soon as it arrives

  • wifi range what are the limits

  • wilibox launches embedded linux wireless platform with industrys first 802 11 stack supporting access point and client modes simultaneously

  • will adobe manage to replace industry work horse quark express by giving adobe indesign for free

  • will voip be a mass market product

  • windows hosting versus linux hosting

  • windows ou linux

  • windows vs linux a comparison

  • wiping a hard drive how to ensure your data is gone

  • wireless home networking choosing the right one

  • wireless network

  • wireless networks how do they work

  • wireless network security

  • working with the registry

  • worms horses bugs and thugs

  • your affiliate business peripherals software computers

  • your fingertips and a phone line perhaps

  • you dont have to be rich to be a pc gamer

  • you do have an email list dont you

  • zero duty channel seeks clarity