Home Networking Tips Advice

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Home Networking Tips & Advice What Is a Home Network?...........................................................................................2 Home Networking Is For You .....................................................................................3 Networking 101 .....................................................................................................5 How Does Home Networking Work? ...............................................................6 Networking Options..............................................................................................7 Wireless Network Pros and Cons .....................................................................8 Protocols Made Easy ..........................................................................................10 Essential Home Networking Equipment.......................................................11 Connecting to the Internet ..............................................................................12 Guidelines For Building A Simple Home Network .....................................14 Setting Up and Using a Shared Printer........................................................15 File Sharing...........................................................................................................17 Security Issues and Guidelines ......................................................................18 Firewalls .................................................................................................................19 Troubleshooting a Home Network .................................................................20

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What Is a Home Network? A home network is a computer network you have in your home. True, but not very helpful, eh? So, let’s dig a little deeper. Most people know by now that in order for one computer to share information with another, it’s necessary to connect them together in some way. Those connections and the computers that are part of them form a network. Just like a spider web, when the trapped fly tugs on one part, a signal is sent to the spider at the other end. In the case of a home network, the web is made up of either cables or radio beams. Those two basic options make up the difference between what is called a cabled or wired network versus a wireless network. As recently as five years ago, a lifetime in the computer world, the wireless option was complicated and expensive. Today, wireless home networks are often less expensive and easier to create. At different points along the web there are junctions called nodes. Those nodes can be in the form of computers, switches or routers.

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Switches provide a place to plug the cables in that allow a physical connection between communicating computers. Routers perform a similar purpose but with more functions, such as the ability to connect multiple networks together and (as the name suggests) route traffic intelligently between them. In many cases, computers themselves can perform those functions. Software within the system can use the network cards in each computer, with a simple switch in between, to allow communication between them. Though routers have become commonplace, that’s still possible and if your needs are fairly simple it can be the cheapest, easiest way to create a home network. But computers, switches and routers aren’t the only possible components of a home network. Familiar devices that go under the general name of peripherals are often part of the home web. One of the reasons for undertaking the expense and effort of creating a network is often to share folders, printer, fax or scanner among multiple computers. If you splurged for a color laser printer or a fax machine at home, you save money by only needing to purchase one device each, instead of multiple printers and faxes for each computer. A home network allows sharing those devices. As part of the basic home network system, you’ll often want to include software and/or hardware known as a firewall. A firewall allows for passing some information sent by trusted sources, but blocks other types of data, or that sent from any other source.

With wireless networks or any home network connected to the Internet, they are a must. Fortunately, routers typically contain some inherent firewall functions. Even software within the OS today can usually perform that function. Putting all these different pieces together in a coherent way that allows you to send and receive files, share printers and more is the process of creating a home network. Of course, doing it in a way that doesn’t get you tangled up in a sticky web requires a bit of homework.

Home Networking Is For You Not too many years ago building a home network was strictly for professionals and true computer geeks. The cost, the complexity and other factors made it a very rough road for anyone else. But the situation has changed.

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Today, the costs have come down on every component. Wireless is not much more expensive, and sometimes less, than cabled gear. A bit of Cat 5 Ethernet cable costs not much more than plain stereo equipment wire. A hub costs a few dollars. Even routers, once $200 or more are now available for little more than the cost of an ordinary switch. At the same time, speeds have increased. Reliability has improved for both cabled and wireless networks. The latter were once just for experiments by hobbyists. A cordless phone call, a wall or just a solar flare hiccup could easily knock your network offline. Distances were limited to a few meters, making wireless networks much less attractive for networking the whole home. Now, they can cover the whole of a large, two story home with ease. But perhaps best of all, besides the lower cost and better performance, home networking is now simpler than ever. Today’s gear comes with better instructions, ones that don’t assume you are a computer or networking expert. The software and hardware both are simpler to configure. The diagnostic tools are easier to use than in times past. At the same time, most people have increased their basic computer knowledge by leaps and bounds. With the Internet, cell phones, iPods being a daily part of everyone’s lives, the intimidation factor is at an all time low. Everyone today knows how to use email. Most people know what HTTP is, how to ping something and other things once considered esoteric. Discussing routers, IP addresses and other aspects is no longer just for wild eyed guys with glasses. Security consciousness has been raised, too. As a result of thousands of articles on credit card or identity theft and other computer related issues, people are much better informed and more cautious. They may not follow all the standard recommendations touted by security professionals, but they’re no longer indifferent. Anyone who has ever been hit by a computer virus, which is just about everyone today, has seen first hand the need for some efforts in this area. There are still a few minor hurdles to overcome. The biggest one is usually just absorbing a fair number of unfamiliar terms, such as protocol, NIC (Network Interface Card) and other related words. Once that wall is breached, the rest is pretty straightforward. Even adding an Internet connection to the home network, so that it can be shared by all systems instead of just one, is very simple today. A little bit of homework, sometimes a modest amount of troubleshooting, and you’re in business. So get in gear and start hooking together those computers owned by each member of the family. You’ll find that printer sharing is easy. You’ll be able to pass files without emailing them from one system and downloading them from another. You’ll find your security enhanced. Most of all, you’ll have the same kind of fun that used to be limited to computer experts. Who wouldn’t want that?

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Networking 101 A network is like a spider web, the basic reason that the Internet (WWW – World Wide Web) is often called that. It’s a series of lines (called routes) that have intermediate and end points (called nodes) that connect devices together. Those connections and routes are what allow the devices to share, input or output information across the network. Along those routes, signals flow that contain information of interest to the network users. Like a trapped fly that tugs on a part of the web, the disturbance is sent down the line, through nodes, to the spider at another point on the web. Unfortunately for the fly, the spider often sends back a reply. Unlike a spider web, though, a computer network sends and receives those disturbances in the form of something called packets. There are other ways to perform the same function, but today almost all networks operate as explained below. Software and hardware on the network cooperate to pass those packets. Packets are chunks of information containing your data wrapped in control information. That control data at the front and back of your data allows routers and computers to know where and how to send your data. In most commercial and home networks, the method uses something called IP, or Internet Protocol. Every device on the network gets assigned an address in the form of what is called a dotted octet, such as 209.131.36.158. In the home, those addresses are usually in a range of: 10.0.0.0 through 10.255.255.255, or 172.16.0.0 through 172.31.255.255, or 192.168.0.0 through 192.168.255.255 Those constitute what are called Private Addresses, since they can’t be sent unmodified over the public networks that form the Internet. They’re used by routers, computers and peripherals in your home network. Private commercial networks, such as those inside companies large and small also use these same address ranges. Something called network address translation, NAT, at a device called a boundary router allows many companies and homes to use the same range without accidentally passing information to and from one another over the Internet. Note that your home computer may have a very different address, such as 70.31.192.243. This is often the case because a single computer connected to the Internet gets an address assigned by the ISP, Internet Service Provider. You then don’t really have just a home network, but are a paying customer of a commercial network.

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When each device - each computer, router, printer - is assigned its own address, the software and hardware can figure out where data is coming from and should go to. It’s what makes possible communication without confusion. The router software and/or hardware, in cooperation with networking hardware and software in each device, routes the data to and from the proper devices using those addresses. The method is in principle the same as that used by the postal system to route letters from one home or business to another.

How Does Home Networking Work? A home network is a set of hardware and software that allows computer-based communication. File sharing, printer sharing and other input and output is a typical part of the home network. But how does it perform those functions? A home network functions in a nearly identical way to that used by private companies when they create what is known as a Local Area Network (LAN). Designations called IP addresses, and some associated easy-for-humans-to-remember names (often called host names) are used to know who and where everything is. For example, when 10.1.1.5 (Computer-Jack) sends a file to 10.1.1.6 (ComputerJill), the software and hardware cooperate to know where and how to send the file from Jack to Jill. The idea is, in principle, the same as that used by the post office. Each home has an address and a letter sent from one home is routed to another by using that address. The return address on the envelope makes it possible to know where to respond. Home computer networks operate the same way, even calling the routing data used ‘an envelope’ that surrounds the data (the words on the letter). Physically, a home network comes in two basic types: cabled and wireless. In a cabled network, wire bundles called Ethernet cables with connectors on each end plug into either a NIC (network interface card) in the computer, printer, fax, … or into a switch/router. Switches or hubs are simplified devices that allow physical connections between components of the network. Routers contain additional software and circuitry to perform more complex functions, such as connecting to the Internet. A wireless network operates the same way, except there is no need for cables. Instead, small devices called transceivers (transmitter-receiver) send and accept information by radio signals. Suppose for example that you want two computers within a home network to both be able to print to the same printer. There are two basic ways to make that possible. In one set up the printer is physically attached to one of the computers. The alternate set up connects the printer to the network itself, not to any individual computer.

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In the first arrangement, the printer is called local, but shareable. Just as you might make files on one computer accessible to another, so it’s possible to allow a remote computer to print to the locally attached device. Computer-Jack then simply shares the printer by using software on the hosting system, Computer-Jill. In the more typical case today, the printer has its own NIC and is attached to a switch or router via Ethernet cables or a wireless transceiver. Each computer on the network then ’sees’ the printer as a device it can use. Scanners, fax machines and even other computers (file servers, for example) operate essentially the same way. Each device gets an address and a name. Software on the device allows it to be configured to make its function accessible to multiple computers on the same network.

Networking Options When you start to design your home network, you’ll be immediately faced with a wide array of choices. Many of them have cryptic names and obtuse descriptions. But don’t be put off by all the techno-babble. Make an effort to get familiar with some of the names because they’re associated with options that affect the design and value of your home network. The first, basic choice is between a cabled network and a wireless one. The choice used to be made for most everyone, given the once high prices and complexity of wireless equipment. But costs have come down and putting a wireless network together today is no more complicated than the more traditional type. Cabled networks today usually run along Ethernet cables. Most Ethernet cabling used is designated by the name: Cat-5. There is another option, though, and that’s to use fiber optic cabling. For home network designers, the extra cost and potential reliability issues aren’t worth the benefits. Ethernet cables will support speeds ranging from the traditional 10 Mb or 100 Mb up to 1 Gb or more. (Here, 10 Mb = 10 megabits/sec = 10/8 megabytes per second.) 10 Gb is not unknown and one company has now produced a wired device that operates at a theoretical speed of 100 Gb. (1 Gb = 1 gigabit/sec = 1/8 x 1024 megabytes per second = 128 MB/s.) The speed is theoretically limited by the cable, but in practice the attached devices are more of a limiting factor. Other factors, such as number of simultaneous users, protocol used and other factors are often even more important in real-world applications. The faster speeds are typically found only in professional networks, however. Wireless devices are often 802.11b or 802.11g type today. The technical definitions are complex, but the practical meaning for the home network

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designer is simple: 802.11b operates at 2.4 GhZ and 11 Mb and 802.11g at 2.44 GHz/54 Mb. Both numbers are important, the frequency (measured in Ghz or 1,024 million cycles per second) and the throughput, in megabits. (1 Byte = 8 bits) The frequency gives you a clue about the likelihood of interference. Some cordless phones and other popular home devices can interfere with your network. That means that when the phone rings and you answer it, your network may see a hiccup. The problem tends to occur more often with wireless cards in laptops, however. The throughput is important, since the numbers are theoretical ratings. The real data transfer rate of, for example, 802.11b tends to be between 6-7 Mb/s, despite the rated speed of 11 Mb/s. For comparison, that’s roughly 1/5 to 1/2 the speed of a DSL or cable Internet connection. So, if you know how long it takes you to download, say, a 10 megabyte file off the Internet, you can easily estimate how fast data will get around your home network. Other systems have been in the experimental stage for several years. One uses the wiring in your home to carry network signals. All you would have to do is plug a special device into an electrical outlet then plug your computer, printer into that via a short cable. Though, some use wireless technology as part of the system. It’s possible to obtain the equipment, but major vendors don’t yet offer this option. For now, it’s best for most home network designers to stick to the standard choices.

Wireless Network Pros and Cons Five years ago, a lifetime in the computer world, the decision of whether or not to go wireless would have been made for most home network builders. The cost and complexity, relatively low reliability and lower speed would have made a wireless network valuable only for the hobbyist. Someone who wanted to build one could have a lot of fun from the exercise. But for practical use, it was a second choice at best. Today, the situation has changed. Wireless equipment has come down considerably in price, relatively speaking. The cost of standard Ethernet cables, switches, routers is typically still less than their wireless counterparts. But the difference has shrunk quite a lot. At the same time, the performance and reliability cost/benefit ratio has shifted. Even five years ago it was easily possible to build a home network that used 100 Mb technology. (100 Mb = 100 megabits/s = 100 x 1 megabits/8 bits/byte = 12.5 megabytes per second.) For more money, then or now, you could build a 1 Gb Ethernet network if you needed the extra bandwidth and speed. That would comfortably support several computers transferring data

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simultaneously. Now, wireless products are very competitive in terms of speed and overall performance. Even a slower 802.11b wireless router is rated at 11 Mb, while delivering real-world throughput of about 6-7 Mb. For only a slightly higher price, on average, you can now get an 802.11g router with a rated speed of 54 Mb and newer, faster models are not far off. Wireless networks offer the maximum in convenience with, in some respects, simplified construction. It’s commonplace for there to be multiple computers in the home today. Most people will not want to have their home look like a computer room. Yet, stringing Ethernet cable around the house inside walls, under carpets or along the floor boards, is a task. Confined to the home office, it may not be a big deal. Wiring the entire house is another matter. With a wireless network, you simply place the wireless router in some location that is sensible for the devices it is going to support. Then, follow the configuration instructions, and you’re in business. The teenager in college upstairs in her bedroom works just fine at the same time as Mom in the home office or Dad in the living room. No need to string a wire to the couch or bed. But there are some limitations and potential downsides. Apart from the higher cost and slower speeds, wireless networks may introduce configuration, security and reliability issues. Though they’ve improved vastly, wireless networks can be more difficult to configure. Wireless routers sometimes have cryptic configurations. Wired routers can too, but it tends to be more so in the case of wireless networks. You’re sometimes unsure whether the issue is software or simply a signal not being sent/received. Security has improved too, though there is an inherent hurdle with wireless networks. Since they don’t require a physical connection, anyone with a wirelessenabled laptop or cell phone who is nearby can, in theory, access your network. But if you follow the directions carefully when configuring the router, this problem can be overcome. Reliability is another area that has gotten much better, though it can’t always match a cabled network. Cable networks can have hiccups, usually when plugging in new devices. Bad cables or connectors are rare, but they do exist.

But wireless network devices are much more subject to possible interference. Microwave ovens, cordless phones, Bluetooth-enabled devices and other common home technology send and receive signals in the same frequency range. Sometimes

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they clash. Charged particle streams from solar flares and other natural phenomenon can interfere with your signal. All in all, though, wireless networks offer flexibility and speed that suits the needs of home network builders well at affordable prices.

Protocols Made Easy Home networking throws novices immediately into a pool of cryptic names and acronyms. Fortunately, home networks are actually fairly easy to build. The first hurdle is little more than becoming familiar with many of those names and letters. Once you learn a little terminology, the rest is often just common sense and carefully following some directions. One of the first terms you’ll encounter, along with a great many associated acronyms, is the word ‘protocol’. The technical definition of the word and the acronyms can become very complex. But, the meaning for your purposes is really very straightforward. A protocol is just a set of rules that have been adopted as a standard method for devices to communicate. For example, the HTTP protocol used by Internet browsers specifies a detailed list of methods for passing Internet data back and forth. More fundamentally, TCP/IP (Transmission Control Protocol/Internet Protocol) is a method dictating how packets get defined and transported on a TCP/IP-based network. Note that there are various ways, involving other protocols, to establish networks and their rules. IBM was one of the earliest with its SNA network philosophy, which was in wide use in business for decades. Though commonly replaced now by TCP/IP, it is still in use around the world. And these two are not the only ones that have been widely adopted at one time or another. While the details are of interest only to professionals and geeks, there are aspects that affect how a home network builder has to proceed. Knowing some of them will help you choose equipment and design your network intelligently. For example, one of the central pieces of home network gear (as it is for professional networks) is the router. But routers come in various types, each associated with a particular protocol. Wireless routers, for example, may use the 802.11b or 802.11g protocol. The technical definition isn’t important, but knowing that the first is rated at 11 Mb (11 megabits/sec transfer rate) versus 54 Mb throughput impacts your network. Though the first is rated at 11 Mb, like many things, that’s the rate under idealized conditions. The real throughput is about 6-7 Mb. And keep in mind that there are 8 bits per byte (equivalent to one character of data). So the actual transfer rate, even ideally, is already only 1/8th of what you actually tend to think of when transferring

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files. Even faster gear that follows the 802.11n standard running at 100 Mb should be available soon. Similarly, most people have no reason to care about the details of the Ethernet protocol. But knowing that 802.3 is the standard protocol used in Ethernet networks helps remove some of the strangeness from yet another cryptic computer number. At the same time, it’s helpful to know that 10BaseT is more or less a synonym for wired Ethernet networks that run at 10 Mb (10 megabits/sec). 100BaseT is the standard for cabled Ethernet networks that use equipment running at 100 Mbps. Every week there will be a new acronym and a new unfamiliar set of numbers created. That’s the computer business and network designers are among the geekiest in the biz. But get familiar with a few of these protocols and related items and you’ll soon be barking them out with the best of them.

Essential Home Networking Equipment There are two basic types of home network, cabled (or wired) and wireless. Either type you choose will have some basic equipment in common, though the specific type will vary. First and foremost, in order for any two devices on the network to communicate, some path has to be established. In a cabled network, that’s done physically by means of wire strands, usually Ethernet cables. They can be any length up to several hundred feet. There are physical limitations before a switch or router has to be introduced between cables, but the length is far greater than most home network builders will have to worry about. In a wireless network, the path may be invisible, but it’s just as real. In this case, radio waves are used to send and receive signals. In principle, they are subject to interference just as broadcast TV signals may be. But in practice, within the home, that’s rarely a problem. Rarely, but not never. Things that generate or interfere with radio signals such as microwave ovens, streams of charged particles from solar flares, metal inside walls can be a problem. Sometimes, a wall is enough to lessen the effectiveness of the wireless signal. Next, you need devices that can send and receive the signals that those wires or beams will carry. A NIC (network interface card), usually in the form of an Ethernet card, is a now familiar part of home networking equipment. They’re often as inexpensive as a few dollars and come in a range of speeds. Today, 10Mb, 100Mb and 1Gb are commonplace.

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There are other speeds as well. An 802.11g wireless network, for example, transmits at 54Mb/s, while 802.11b operates at 11Mb/s. As time progresses and costs come down, the higher speeds are more and more dominating the market. Higher speeds are available and becoming more common. A NIC can be the more traditional type that connects to Ethernet cables, or it can be a wireless card that has a transceiver built-in to send and receive radio signals. But the NICs in different devices (such as two computers on the network) are rarely connected by the cables directly. In almost all cases they run to a switch or, these days more often, a router. A switch or hub is a small device with ports (holes) that cables can be plugged into. They’re ultra low cost (often just a few dollars) and adequate for simple networks that don’t require a connection to the Internet. More often today, home network builders will use one or more routers.

A router is just what it sounds like, a device that routes traffic. It determines how and where to direct data by using a series of IP addresses (such as 10.1.5.142) and software/hardware designed to receive data from some devices and send data to others. Routers come in two basic ‘flavors’ today, cabled and wireless. Each type comes in a variety of models from different vendors. They have different software, which is usually proprietary and offer different functions. Some for example, may have virus protection built in. They may vary according to the number of ports, which determines how many devices can be plugged in. They’ll vary according to how fast they actually operate at, along with variations in rated speed (54Mb rated ~ 6 Mb actual). There are other devices that may, and usually do, form part of a home network such as a cable modem, DSL or satellite modem for connecting to the Internet. But those listed above are the bare essentials to get started.

Connecting to the Internet Most home network builders will not be satisfied just to trade files among the computers on the home network. That means they will want to connect at least one system to the Internet. In the usual scenario, network builders will want all systems on the home network to have access to the Internet as well. There are multiple ways to do that, each with pros and cons in terms of cost, complexity, performance, reliability and security.

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Independent Connections The first, and almost always the most expensive, option is to have multiple, independent connections to the Internet. Few will want to absorb the cost of having multiple DSL, cable or satellite modems. Few will want to pay their ISP for double, triple or more connections to the Internet. But this method does have some advantages. Each computer that connects will have a completely independent connection, even though as part of the same home network they can still share files, printers and other devices. Each computer gets the full security features offered by the ISP without any complex configuration on the part of the home network designer. Each computer gets the full bandwidth, so performance is optimal. And you have built-in redundancy. If one connection goes down, you have another that can still access the Internet. Alternatively, it’s possible to use one DSL or cable modem, insert a hub inline, and plug multiple computers into the hub. Then purchase independent IP addresses from the ISP. This only costs one DSL or cable modem, but extra IP addresses are usually a bit pricey. Performance is still usually very good for each system, provided the router can handle your average traffic without a big slow down. Internet Connection Sharing Another option several steps down in terms of cost comes at the price of a little bit of complexity. It’s possible to use one computer as a router and to use Internet Connection Sharing software in Windows or Linux to make the connection available to other computers on the network. In this scenario, one computer connected to the Internet and assigned a public IP address by the ISP gets an extra NIC installed. To that second adapter is plugged a cable that runs to a NIC in a second computer. Using Internet Connection Software that comes with Windows or Linux, it’s possible to configure both systems to share the single Internet connection. Cheap and semi-reliable. But it has some drawbacks. Any network use on the part of the second computer will impact the first one, the one that has the direct connection. All network traffic for the second computer has to be managed by the hardware and software in the computer with the direction connection, so its performance slows down. Also, if the first computer fails, or even is just rebooted or shut down, the Internet connection goes away for the second computer. Router and Hub With decreasing costs and ease of configuration, another option is becoming the best for most people. In this case, a router is connected to the DSL, cable or satellite modem. It acts as a gateway for all network traffic to and from the Internet by any system on the home network.

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Sometimes routers will allow multiple connections, in some cases a hub may be required in order to provide enough ports for all the home network connected devices. But hubs are reliable and cheap, so it adds only a tiny amount of complexity to the design. With this setup, each user gets the full security available from the ISP and the router acts as a common firewall to add to that. Most routers will handle the traffic from all users pretty well, provided no single user is constantly downloading large files from the Internet. File sharing between each computer is safer since each is behind the firewall. Network configuration is marginally simpler since you can use DHCP-assigned IP addresses using the DHCP-server function found in most routers. That way, as you swap laptops and other devices in and out of the network, there’s no need to make sure you haven’t assigned a duplicate static IP address. Only a short period of ‘homework’ is required for most home network builders to catch on how to implement this scenario. The instructions that come with most routers will provide enough information to set it up. The cost is modest today and provides the best alternative for most situations.

Guidelines For Building A Simple Home Network For many people, their computing needs at home are fairly simple. Even today when it’s more commonplace for multiple family members to have their own computer, the systems are often stand alone devices. They have little or no need to share data. ‘Sneaker net’, or sharing data by passing a CD from one to the next, is often good enough. Emailing over the Internet is, of course, another now-common method. But for those who want to take the next step and build their own home network, the timing is good. Costs have come down and complexity is less than ever. The initial hurdle for most home network wannabees is simply to get over the techno-babble barrier. Familiarity can help. The basic equipment needed is fairly simple to understand. You’ll need something called Ethernet Cat-5 cable if you plan to build a wired network. Just estimate how much you need by planning out where you want to connect devices to/from and then add about 20% more. You always need more than you think you do. For wireless networks, which sometimes cost more, you can skip that requirement. Those cables or, in the case of wireless networks the radio beams, have to have something to connect to. So, you’ll need a hub or switch or router. A hub is the simplest and cheapest device. It’s just a small device with ports (holes) to plug cables into. A switch looks the same but has slightly more function. A router is more costly, but has the most features. For connecting to the Internet, it is almost a must.

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‘Almost’ because it is possible to use one of the computers to do Internet Connection Sharing. But it’s often better to have a dedicated router, rather than consuming resources on one of the computers in the network. Lastly, you need devices - called adapters - inside the computers, printers, fax machines that you want to connect to the network. They can be standard 10/100 Ethernet NICs (network interface cards) or 802.11 (b or g) wireless cards that perform the same function in a cable-free network. There are other possbile methods and associated gear, as well. With Ethernet, you have two basic choices of speed 10 Mb or 100 Mb. But the price difference is so little these days, that it’s usually pointless to get anything less than 100 Mb gear. They typically support older devices that will run only at the slower speed. Gigabit Ethernet is an option, but it’s more expensive than most home network builders may want to pay. Install, attach and/or setup all hardware according to the manufacturers’ directions. Each device on the network will need at least one IP address. These are the dotted octet numbers you may have seen when accessing the Internet, such as 70.1.2.125. In your home network, they will have numbers like 192.168.0.1 or 10.121.0.1. Focus your numbering scheme starting at the router. Consider that device the central hub by imagining a star with rays coming out. The router is at the center and each cable or radio beam is a ray. The endpoints are where your connected devices will be. If the router is assigned a number such as 192.168.0.1 then computers, printers and other devices on the network may have numbers like 192.168.0.2, 192.168.0.3, etc. Never assign the same number to two different devices.

For specific instructions on how to assign these addresses, you’ll need to read the directions for your router and your computer. Each one is different.

Setting Up and Using a Shared Printer One of the reasons many home network builders go through the expense and effort in the first place is to share a printer. If someone splurges several hundred to several thousand dollars for a color laser printer, they don’t want to shell out that money for each computer in the home. Fortunately, sharing a printer in a Windows-based home network is easy. It isn’t much more difficult in Linux. There are two related steps: setting up hardware and configuring software. Whether wireless or cabled, the hardware connections need to be established first.

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The hardware set up is generally very straightforward. There are two ways to go about it. Either the printer is attached locally to one computer on the network, or it has a NIC (a network interface card, an adapter) of its own. In the second case, the printer plugs into the network just as a computer does. It gets an IP address just as any computer on the network does. In the first case, the printer doesn’t require a separate IP address since it’s accessed via the computer to which it is locally attached. Next, the software configuration has to be done. First, for a network attached printer, it will need to be assigned an IP address. Select one in the range associated with your home network. For example, suppose your main computer or router is 192.168.0.1 and you have two other computers on the network Jack/192.168.0.2 and Jill/192.168.0.3. You could select then the next available IP address, 192.168.0.4 or skip a few to allow extra numbers for more computers. It doesn’t matter, since all IP addresses are equal, provided they’re in the proper range and don’t start with the gateway address, 192.168.0.1. The specifics of how to assign the IP address vary from printer to printer. Consult the manual. Just ensure that you don’t accidentally assign the same IP address twice on your network. That will invariably cause problems since the router and other systems won’t be able to correctly direct traffic on the network. The following instructions may vary slightly depending on which Windows version you are using. For a locally attached printer, all it needs is a name. Use Control Panel/Printers. Select the printer you want to share. Then, in the tasks pane, click Share This Printer. Open the Properties dialog box and click on the Sharing tab. Enter a name and click OK. The printer is now shared. Now that you have a network printer, you can connect to it from all computers on the network. To add a network printer to your computer, use Control Panel/Printers again. Click in the tasks pane Add a Printer. Instead of adding a local printer choose for network printer and browse the network for the right printer. Be sure to place the printer in some appropriate location. You may want to hide it in a closet to reduce noise, or put it in a hallway for easy access around the house. Or, you may want to centralize your printer, fax, scanner in the home office. The physical location makes no difference to the network hardware or software, only the IP address and/or name is important.

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File Sharing Once you have a home network established, there are several ways to make use of it. One popular goal is to share files between one computer and another without having to use ’sneaker net’, like trading files by a CD/DVD or, yikes!, by using a floppy disk.

A lot of file swapping goes on via email over the Internet, of course. That’s not technically sneaker net. But it’s still a roundabout method. Your email provider may put a low limit on file attachments, so for larger files you have a problem. Also, your Internet connection may be (and often is) a lot slower than the local speeds obtainable on a home network. Fortunately, for computers on a Windows-based home network, file sharing is very simple. In Linux, it isn’t much more difficult. Here are two different methods: If you have a computer with an adapter that shares an Internet connection, that system is often a kind of hub for your home network. It often, therefore, serves multiple duty as a file server. It performs that function in at least two ways: FTP or Shares. FTP is now decades old, but still a highly useful means of copying files from one system to another. One system must be an FTP server, the other is the FTP client. Most web servers, for example, have FTP server software installed. You can use one of the many FTP client software packages available on the Internet. Or, you can use the command line (DOS window) built into Windows. Click Start/Run, then type ‘cmd’ into the dialog box (without the quote marks). Type ‘ftp -?’ (again without quote marks) and it will show you different parameters you can specify, different ways to execute the command. The different methods/parameters are there so you can send/receive to/from different systems and more. The other method consists of using something called File Shares. Simple File Sharing is always turned on in Windows XP Home edition based computers. To turn Simple File Sharing on or off in Windows XP Professional, simply double click My Computer. On the Tools menu, click Folder Options. Click the View tab, then select or deselect the Use Simple File Sharing check box. You should set the security appropriately for the level of access you want to grant for folders and files. You can make the files available as Read Only, which prevents anyone from accidentally deleting them. But to transfer files to the other system, you will have to have Write access. To grant complete control, Full Control is the correct choice. Right-click a folder, and click Sharing and Security to set the appropriate level. It can be cumbersome, at first, to go through all the effort of either method when emailing through the Internet is so simple. And, for occasional file sharing, that may

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well be true. But if you share files regularly, a little time spent learning these methods will save you a lot of time over the long run.

Security Issues and Guidelines Home networks are less expensive and easier to set up than ever. But sometimes the knowledge needed for building them isn’t accompanied by guidelines on how to secure them. In some cases, those guidelines are simply ignored. In either case, that’s a data disaster waiting to happen. It’s certainly possible to be paranoid about security. That excessive concern is just that, excessive. But a certain amount of caution is wise, not paranoid. Security is like medical insurance. You don’t need it often, but when you do you’ll need it badly. If you don’t have it, the consequences can be severe. Wireless home networks, which are becoming the more popular option thanks to their flexibility and lowered costs, are particularly prone to security issues. In theory, and often in practice, someone with a wireless-enabled laptop can simply drive by your home and tap into your network. If all they do is steal a little bit of bandwidth that’s not much of a problem. But if they happen to be clever and malicious, they can now more easily implant a virus into systems on your home network without your knowledge. Internet use has similar risks, but in that case you typically have to download an attachment from someone you don’t know to get infected. That’s easy to avoid. But in the case of a wireless home network, no action is required on your part to get infected. Even if you’re following good Internet file sharing practices, you are still vulnerable. Even in a cabled network, it’s possible of course, for someone to break in while you’re away. Most such incidents will revolve around stealing property. But computer infection is one way for a disgruntled employee, a party to a lawsuit or other angry person to take revenge undetected. In either type of network, the solution is essentially the same. Practice the same good habits you use for Internet data sharing and amplify them. Make sure every computer on the network has a password that is required in order to access the system. Leaving a system unprotected to save a few seconds of inconvenience at home exposes your whole network to unnecessary risk. Always change the password on your router. The defaults for most popular vendors’ products (often the same from one to another) are known by just about everyone with the skills to do harm. Make it harder for them to do damage by this simple step.

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Configure wireless routers according to the manufacturers’ instructions, in order to prevent unauthorized access. All wireless routers today use WAP (Wireless Authentication Protocol) to prevent drive-by’s from accessing your system. Use it. Monitor activity on your network and the systems connected to it. Don’t allow friends of your children, neighbors and others to use your network until you know them well. The computer knowledge of most teenagers would astound most adults today. Most are well meaning, but some haven’t yet learned how to use a home network in a secure way. Treat your home network much the same way you treat your credit cards. Don’t provide physical access or pass out information to anyone that you don’t want to have access to it. It’s often a short step away from giving them access to your money. It’s an even shorter step to your valuable data.

Firewalls In building construction, a firewall is a physical barrier to help prevent the spread of a fire from one room to another. The home network equivalent is well named. The software and/or hardware that constitutes a firewall makes it more difficult for dangerous programs or unauthorized users to access your system. Firewall protection has two directions. In some cases, you want to prevent data and/or programs from leaving your computer. This helps prevent any virus you contract from spreading to other systems on the network or the Internet. In the more usual case, your firewall is configured to prevent unauthorized programs and visitors from accessing your system from the outside. That unauthorized access can come from different sources, typically the Internet, but also other machines on your home network. A driveby hacker with a wireless enabled laptop, for example, can access your network and implant a virus. Blocking certain types of access can make his job harder, even though his system is temporarily inside your network. But blocking all types of traffic from all sources in both directions would defeat the purpose of having a network at all. So, network security always strives for a compromise between locking out and opening up. Where to strike that balance is sometimes a gray area. However, there is a fairly standard list of items that anyone will want to focus on. Keep in mind, the two most common protocols used: TCP and UDP. TCP is bidirectional, UDP is a broadcast that doesn’t require a two way connection. Though, UDP traffic can travel in either direction, such as when you ping. Opening up a port on your firewall often involves specifying both the number and the protocol. The default idea should be to close anything you don’t know you will need. This means only open a port or protocol in the direction you need and only once you’re sure you need it. The default should be ‘closed in both directions’.

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HTTP - This is the protocol used for all standard Internet data requests, whether sending (uploading, for example) or receiving (such as accessing a web page). Configure your firewall to leave open Port 80. For secure transactions that use HTTPS, such as many banking sites, open Port 443. 8080 is also often used. FTP - Many people still use FTP to transfer files to and from computers over the network. That requires opening Port 20. SMTP - Most email programs use SMTP to send and receive emails. Thus, open Port 25 to allow this function to operate. POP3 - POP3 is also part of many email functions, so open Port 110 for incoming traffic. DNS - In order to translate names to IP addresses, DNS has to be able to send and receive packets. That requires opening Port 53 for traffic in both directions. DHCP - For Internet access in which your IP address is dynamically assigned and if you use this feature in your home network, open Port 68. DOOM - The popular networking game Doom requires Port 666. If you don’t play it, don’t open it. Remember, the default should always be ‘closed in both directions’ for any service you don’t use. There are many other standard ports, such as 1433 for Microsoft SQL Server use. Each program should provide documentation about any and all ports it needs, the protocol used and the direction. Proceed with care.

Troubleshooting a Home Network Troubleshooting a network can take myriad forms. But most problems tend to repeat themselves. The first step is usually distinguishing between a software problem and a hardware problem. Unless you have specific reasons to question some other aspect, start troubleshooting by checking the hardware on your network. One of those reasons might be that you’ve just installed some new software that affected network settings. How you do that in detail depends on how your network is arranged. Assume, for simplicity, that you have three computers connected to a simple hub or switch. Suppose one computer is connected to the Internet, and uses Internet Connection Sharing. It will form the focus of the network. Check its IP address, which might look like 192.168.0.1. This may be the address of the router instead. See the instructions of your router for details.

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To check an IP address, you can use Control Panel/Network Connections (Windows XP). But it’s a good idea to get used to executing command line utilities to diagnose network issues. Click Start/Run, then type ‘cmd’ into the dialog box, leaving off the quote marks. This opens a ‘DOS window’. Type: ipconfig/all. You’ll see the IP address and related information. Next, ping the IP address of the second or third computer on your network. If you get back ‘Request timed out’ you have a loss of connectivity between the computer executing the ping and the one you are pinging. Ping from 192.168.0.1 to 192.168.0.2, then from the second to the reverse. By using different computers to ping to and from you can often isolate where the problem is. Check the lights on the network adapter (NIC or network interface card) on both computers. They should be green and blinking when doing the ping. Check the hub or switch to which they are attached. The light should be lit continuously. Similar considerations apply if you are using a router. If one of the lights is not lit, check the cables attached to that port. It’s rare, but not too rare, for a cable or connector to go bad. What’s less rare is for a newly attached device’s cable or connector to malfunction. Cables get bent, crimped and subject to a number of physical stresses that can cause the wires inside to come loose. It only takes one to cause the whole cable to be bad. Similarly, if you have a wireless network, check the lights on the adapter(s) and the router. Most routers will come with diagnostic software that will help you trace down the source of the problem. For cabled or wired networks, a cable diagnosis meter is a handy device. If you can afford one, something called a sniffer is very handy for either type of network. With it, you can see packets being passed back and forth and gather other useful information. If your network is built in sections, the ‘tracert’ command can be a great adjunct to the ping utility. It will allow you to gather information about packets as they travel from one hop to another. Execute: tracert -? from within a DOS window to get more details.

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