7.1. Networking 101 A network allows two or more computers to connect to each other to share files and printers, exchange data, and share an Internet connection. Networks have been common in large companies for decades, are ubiquitous in small businesses, and have become extremely common in homes as well. Home networks have become inexpensive and easy to set up, and as more homes have multiple PCs, networks are commonly used to share a broadband Internet connection, such as a DSL or cable modem. Among the things you can do with a simple network are the following:
File sharing Documents and even some applications stored on one computer can be accessed by another computer on the network, as though they were on the remote computer's hard disk.
File synchronization Files can be automatically synchronized between several computersfor example, between a PC and a laptop. When the laptop is disconnected from the networkfor example, to take on a tripthe files can be altered on the laptop, and when it plugs into the network, those files are automatically copied to the PC, where they can be worked on.
Device sharing Printers connected to one computer can be used by any other computer on the network. The same goes for many scanners, backup devices, and high-speed Internet devices, such as DSL and cable modems.
Online gaming Networkable games can be played against other users on your local network or even over the Internet; after all, it's more fun blowing up your friends than computer-generated characters.
Communication and collaboration Send and receive email, chat, and even videoconference across the room or across the country in seconds, over any type of network connection. Windows Vista includes a slew of new collaboration features, including the ability to give live presentations over a network.
Web exploration The Web has become ubiquitous. Using Internet Explorer or the web browser of your choice, you can retrieve information from the other side of the world as easily as you can from the other side of town.
Data collaboration A network connection allows two or more users to simultaneously access the same database, which is useful for patient tracking in a doctor's office, parallel development of an application in a software company, or keeping track of bills and expenses at home.
Administration Maintain and troubleshoot multiple computers over a network more easily. Using Remote Desktop sharing (or a third-party alternative), control a remote computer as though you were sitting in front of it. Rather than spending several hours over the phone helping someone far away fix a problem with his computer, fix it yourself in a few minutes. The ability to perform these tasks depends only on your software and the speed of your connection. Because Windows Vista includes built-in support for networking, as well as starter applications that provide all of the functionality just described, all you have left to do is to set it up. It's important to note at this point that when you connect your computer to a network, you can dramatically increase its exposure to hackers and viruses. See the "Implementing Network Security" section, later in this chapter, as well as the security advice in Chapter 8, for more information on safeguarding your computer. 7.1.1. Networking Terminology Understanding networking terminology is essential to making sense of the software and hardware used to assemble a network. The following terms are used throughout this chapter, as well as in just about any conversation about networking:
Bandwidth The capacity of a network connection to move information. If a network is capable of transferring data at 100 Mbps (megabits per second) and two users are simultaneously transferring large files, they will have only about 50 Mbps of bandwidth apiece at their disposal. See "Hubs and switches," later in this list, for limitations.
Bluetooth A short-range radio frequency (RF) wireless standard used to connect handheld devices and peripherals at speeds from 1 to 2 Mbps. It has mostly shown up in mobile phones, although Bluetooth-capable GPS units, printers, mice, keyboards, and other devices that need to transmit modest amounts of data over short distances are on the market and gaining in popularity. Windows Vista supports Bluetooth natively. Bluetooth devices use a passkey to connect to your computer. This is usually used only when two devices meet (the "handshake") for the first time. During this time, the two devices set up a trust relationship based on stronger security keys than the short password used for the initial handshaking procedure. From that point on, the computer and Bluetooth device can be sure of each other's identity, which is why your mouse won't suddenly start controlling your office mate's cursor. One security measure: before you connect any Bluetooth device to your PC, you must check the "Allow Bluetooth devices to find this computer" box in the Bluetooth Control Panel and then configure your Bluetooth device to be "discoverable." Once you add the new device, it can connect to your PC at any time, even if the "Allow Bluetooth devices to find this computer" box is later unchecked. Your connections can be encryptedif your applications and drivers provide it. Due to Bluetooth's relatively short range, there's not a lot that passersby can do, although hackers have risen to the challenge with bluejacking, or sending usually harmless messages to victims' phones (there are rarer activities in which malicious hackers use specially crafted messages to exploit vulnerabilities in certain models of phones). You can limit your exposure to unwanted messages by turning off discovery mode, thereby ensuring that only devices you've specifically configured to work with your device can talk to it.
Dynamic Host Configuration Protocol (DHCP) A protocol used to assign a unique Internet Protocol (IP) address to each computer on a network. The IP address is assigned dynamically every time a PC connects to the network so that the PC may receive a different IP address every time it connects. A PC that has a static IP address, on the other hand, has the same IP address every time it connects, and a DHCP server does not need to assign it the address. Windows Vista lets you configure PCs for either dynamically assigned addresses or static addresses. (See "Network Connection Properties (Includes Wired and Wireless Connections)," later in this chapter, for details.)
Domain A network that uses the client/server model so that one or more servers provide central resources for the network, such as file sharing, printer serving, and email. PCs (called clients) connect to servers in order to connect to the network. Domains are common in large organizations, and multiple LANs, spread across the globe, can be connected to a single domain. Don't confuse these domains with Internet domain names (such as oreilly.com).
Ethernet The technology upon which the vast majority of LANs are built. A basic Ethernet connection is capable of transferring data at a maximum of 10 Mbps, and a Fast Ethernet connection can transfer data at 100 Mbps. A device capable of communicating at both speeds is typically labeled "10/100." There are also gigabit Ethernet connections, which, as the name suggests, transfer data at 1 Gbps.
Firewall A layer of protection that permits or denies network communication based on a predefined set of rules. You can use a firewall to restrict unauthorized access from intruders, close backdoors opened by viruses and other malicious applications, and eliminate wasted bandwidth by blocking certain types of network applications. Windows Vista includes a firewall. For details, see Chapter 8.
Gateway A piece of hardware that ties together two networks that use different protocols or connects two IP networks. For example, a gateway may connect a local wireless or wired network to the Internet. Gateways are commonly built into home routers, which allow PCs in a home to communicate with one another and connect to the Internet.
Hubs and switches Devices on your network to which multiple Ethernet connections (called nodes) are made. See Figure 7-2 for an example. The main difference between a hub and a switch is a matter of performance (and cost). A switch is capable of handling multiple, simultaneous, full-bandwidth connections, and the less expensive hub throttles all connections such that, for example, three simultaneous connections can each use only one-third of the total bandwidth.
Hotspot A public wireless network, available at many cafes, coffee shops, libraries, airports, and other locations. It allows anyone to connect to the network using WiFi in order to get Internet access. Some hotspots are for-pay, and others are free. Some cities have turned entire downtown areas into giant hotspots so that anyone can connect, often for free. For hotspots near you, check out http://www.wi-fihotspotlist.com. For a list of free hotspots, see http://free-hotspot.jiwire.com. Note, though, that hotspots often appear and disappear frequently, so those sites may be out-of-date.
IP address A number composed of four bytes (e.g., 207.46.230.218) corresponding to a single computer or device on a Transmission Control Protocol/Internet Protocol (TCP/IP) network. No two computers on a single network can have the same IP address, but a single computer can have multiple IP addresses (for example, a gateway server has two IP addresses: one for each network that it bridges). Most elements of the address can range from 0 to 255, providing approximately 2564 or nearly 4.3 billion possible combinations. Network Address Translation (NAT) is used to translate an address from one network to another. This is useful, for example, when a firewalled LAN is connected to the Internet (for example, this translation is what makes it possible for web servers to send responses back to the correct machine on your network, even though all the Internet traffic is funneled through a single cable or DSL modem). On the Internet, dedicated machines called nameservers are used to translate named hosts, such as www.microsoft.com, to their respective numerical IP addresses. See "Windows IP Configuration" and "NSLookup," later in this chapter, for more information. The four-byte addressing scheme is employed by the currently used version of networking, called IPv4. But Windows Vista also supports IPv6, which greatly expands the number of IP addresses available, as well as adds security and Quality of Service (QoS) features. An IPv6 address looks like this: fe80::28ff:b329:f8b3:a44e. IPv6 is not yet in widespread use; when it is, it will be used more for large corporate networks than for home or small-business networks.
LAN Local area network, a designation typically referring to a network contained in a single room or building.
Mbps Megabits per second, the unit of measure used to describe the speed of a network connection. Ethernet-based networks can commonly transfer data either up to 10 or 100 Mbps, although now gigabit networks (1,000 Mbps) are becoming common as well. High-speed leased-line, DSL, and cable modem connections typically transfer data at up to 15 Mbps and faster; the fastest analog modems communicate at a glacial 56 kbps, or 0.056 Mbps. Because there are eight bits to a byte, you can determine the theoretical maximum data transfer rate of a connection by simply dividing by 8. For example, a 384 kbps connection transfers 384 / 8 = 48 KB of data per second, which should allow you to transfer a 1 MB file in a little more than 20 seconds. However, more is going on than just data transfer (such as error correction), so actual performance will always be slower than the theoretical maximum.
NIC Network interface card, commonly known as an Ethernet adapter or network adapter. If your computer doesn't have built-in Ethernet, you'll need a NIC to connect your computer to a network. For desktops, your NIC should be built into your motherboard; for laptops, your NIC should also be built-in, but it may also be a PCMCIA (PC Card) card. Most laptops also include built-in WiFi NICs. Universal Serial Bus (USB)-based NICs can also be used with both desktops and laptops.
Peer-to-peer network A network in which there is no central server, and PCs communicate directly with one another and share their resources. Home networks, such as those built on home routers bought from retail stores or online, are peer-to-peer networks, as are many small-business networks. Larger networks commonly use central servers instead of peer-to-peer networking. The term peer-to-peer is sometimes used in another sense, to refer to applications, such as BitTorrent, that directly connect computers over the Internet or a network to allow them to share files.
Ports A number representing the type of communication to initiate. For example, web browsers typically use port 80 to download web pages, so web servers must be "listening" at port 80. Other commonly used ports include port 25 for sending email (SMTP), port 110 for retrieving email (POP3), port 443 for accessing secure web pages, port 21 for FTP, port 23 for Telnet, port 22 for SSH, port 53 for Domain Name System (DNS), port 119 for newsgroups, and port 6699 for peer-to-peer file-sharing applications.
PPP Point-to-Point Protocol, a protocol used to facilitate a TCP/IP connection over long distances. Windows uses PPP to provide an Internet connection over ordinary phone lines using an analog modem. Some DSL connections use PPPoE, a related technology.
PPPoE Point-to-Point Protocol over Ethernet, which encapsulates PPP frames inside Ethernet, is used primarily for DSL modems.
Protocol A protocol is the language, so to speak, that your computer uses to communicate with other computers on the network. The TCP/IP set of protocols is the de facto standard for LANs and WANs and is required for Internet connections.
Router Transfers data packets among networks and inside a network, as well as routes the packets to their proper locations. A router, for example, handles the work of examining data packets on a network, seeing their destination, and then sending them on their way. On the Internet, routers commonly send data packets to other routers, which send them to other routers, until the packets reach their final destination. Many people confuse routers with switches. A switch is a passive device that connects devices to form a network, and a router actively routes packets. A home or small-business router actually has more hardware in it than just a router, and it typically includes a hub (or a switch) and a gateway so that a single device can form the basis of an entire network. If you use the Network Map feature of Windows Vista to map your home wireless router, it will show a switch, the router itself, and a gateway as separate devices (see Figure 7-1), even though they are all combined into a single piece of hardware. You can create your own network map by opening Control Panel  Network and Internet Network and Sharing Center and then clicking "View full map." Figure 7-1. Windows Vista's Network Map, which shows a switch, router, and gateway on a home wireless network 
Server A computer in a network that performs a service of some kind, such as handling email, storing and serving files, running a database or other application, and so on. Home networks commonly do not use servers, and corporate networks do.
Service set identifier (SSID) A name that identifies your wireless network. Routers come preconfigured with SSIDs (for example, Linksys routers all have the SSID "Linksys"), but you can (and should) change them in the router's setup software.
TCP/IP Shorthand notation for the collection of protocols that includes Transmission Control Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), and Internet Control Message Protocol (ICMP). TCP/IP is required for all Internet connections and is the standard protocol for most types of modern LANs.
Topology The physical layout of your network. See the next section, "Planning Your Network," for more information on how topology comes into play.
Virtual Private Network (VPN) A virtual network that allows private, encrypted information to be sent across the Internet. Companies often use VPNs to allow their employees to connect to a corporate network remotely from home or while traveling. Employees use the Internet to connect to the corporate network, but all of their communications are encrypted and travel inside a virtual "tunnel" so that they are private and secure. Windows Vista includes built-in capabilities to create VPN connections. For details, see "Set Up a Connection or Network," later in this chapter.
WAN Wide area network, or a network formed by connecting computers over long distances. The Internet is an example of a WAN. On a home router, several ports are typically used to connect computers to the home network, and a single WAN port connects the home network to the Internet.
WiFi (802.11x) The current standard(s) for wireless networking. The 802.11x series isn't one technology, but several. But when we talk about WiFi connections, we usually mean 802.11gthe current worldwide standard, especially for home networks, which offers transmission speeds up to 54 Mbps (with typical throughput of 20 Mbps). The previous commonly used WiFi standard was 802.11b, which offers speeds of 11 Mbps (5.5 Mbps real-world speed). Many public hotspots still use 802.11b rather than 802.11g, and older networks use 802.11b as well. 802.11g networking gear is backward-compatible with 802.11b networks and can connect to them, although obviously at the lower network speeds. The next generation of WiFi, 802.11n, is just being introduced and can theoretically offer speeds of up to 540 Mbps, although as a practical matter in the real world it will rarely, if ever, give that real speed. In fact, wireless networks do not transmit data at their maximum possible speeds because of interference, distances between transmitters and receivers, and so on. (Also on the market is 802.11a, although its limited range and lack of compatibility with the "b" and "g" standards generally make it a poor choice. It is not in widespread use.) These standards include encryption to keep your data secure and to make sure that only authorized computers are able to connect. The most common methods are WiFi Protected Access (WPA), WPA2 (also known as 802.11i), and the older Wired Equivalent Privacy (WEP). WPA2 is the most secure, WPA is the second most secure, and WEP is the least secure. Your hardware needs to be compatible with the encryption standards in order to use them. Older equipment may not be compatible with WPA2, and in some instances very old equipment will not be compatible with WPA. A driver or firmware upgrade may solve the problem; if not, you will need to purchase new hardware. A wireless network typically consists of a wireless router (the access point) connected to the Internet via broadband, and one or more computers that can tap into the router. (You can have a wireless network without a wireless router using "ad hoc" mode, but only between two computers at a time.) Most new laptops come with WiFi support built in, although desktop PCs may require a wireless PCI card or USB adapter. Windows Vista can access any WiFi connection out of the box if you have the necessary hardware.
Workgroup A group of computers that are connected via a peer-to-peer network and share resources such as printers and files. Most people confuse a workgroup with a network. A single network can have multiple workgroups in it, and you can add and delete workgroups to the network. When you set up a network in Windows Vista, Windows automatically creates a workgroup for it and gives it a name. You can, however, change the workgroup's name and add new workgroups to the network. Workgroups are peer-to-peer, and in Windows Vista you can easily change the workgroup to which your PC is attached. See "Change Workgroup or Domain," later in this chapter, for details.  | If you're using a Mac OS X or Linux system to exchange files with your Vista system using Windows file sharing, you may want to edit the /etc/smb.conf file (you'll need to have root access to do this) to use the same workgroup as your Windows PCs. |
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