The traditional version of the IP protocol is version 4: IPv4. Each connection on a TCP/IP address (logical address) is assigned a unique IP address. The format of the IP address is four 8-bit numbers (octet) divided by periods (.). Each number can be 0 to 255. For example, a TCP/IP address could be 131.107.3.1 or 2.0.0.1.

IP addresses are manually assigned and configured (static IP addresses) or dynamically assigned and configured by a Dynamic Host Configuration Protocol (DHCP) server (dynamic IP addresses). Because the address is used to identify the computer, no two connections can use the same IP address. Otherwise, one or both of the computers would not be able to communicate, and will usually see a message stating “IP address conflict.”

The TCP/IP address is broken down into a network number and a host number. The network number identifies the entire network, and the host number identifies the computer or connection on the specified network.

Usually when defining the TCP/IP for a network connection, IT managers also specify a subnet mask. A subnet mask is used to define which address bits describe the network number and which address bits describe the host address. Similar to the IP address, the format of the subnet mask is four 8-bit numbers (octet) divided by periods (.). Each number can be 0 to 255. For example, a subnet mask could be 255.0.0.0, 255.255.255.0, or 255.255.240.0.

For example, if you have an address of 15.2.3.6 and you define a subnet mask of 255.255.255.0, 15.2.3.0 defines the network address where every computer on that network must begin with 15.2.3. Then, each computer must have a unique host number, making the entire address unique. Because the first three octets are defined as the network ID, the last octet defines the host ID. Therefore, the one host (and only one host) would have a host ID of 0.0.0.6 located on the 15.2.3.0 network.

If an individual network is connected to another network and users must communicate with any computers on the other network, they must also define the default gateway, which specifies the local address of the router. If the default gateway is not specified, users will not be able to communicate with computers on other networks. If the LAN is connected to more than two networks, users must specify only one gateway, because when a data packet is sent, the gateway will first determine whether the data packet needs to go to a local computer or onto another network. If the data packet is meant to be sent to a computer on another network, the gateway forwards the data packet to the router. The router then determines the best direction that the data packet must go to reach its destination.

If you are connected to the Internet, you need a default gateway. Because the default gateway address is an address of a host, it also is a four 8-bit number (octet) divided by periods (.). Each number can be 0 to 255. Because it must be connected on the same network as the host, it must also have the same network address as the host address.

Because TCP/IP addresses are scarce for the Internet (based on the IPv4 and its 32-bit addresses), a series of addresses has been reserved to be used by the private networks. These addresses can be used by many organizations because these addresses are not seen from outside of the local network. The addresses are as follows:

To enable these addresses to connect to the Internet, you use a router that supports Network Address Translation (NAT), also known as IP masquerading, which translates between the internal private addresses and the public Internet addresses.

Since the TCP/IP protocol and the Internet became popular, the Internet has grown and continues to grow at an exponential rate. Eventually, the Internet will run out of network numbers. Therefore, a new IP protocol called IPv6 is replacing IPv4.

IPv6 provides a number of benefits for TCP/IP-based networking connectivity, including the following:

IPv4 is based on 32-bit addresses (four 8-bit octets), which allows a little more than 4 billion hosts. IPv6 uses 128 bits for the addresses, which can have up to 3.4 x 10³⁸ hosts. Thus, IPv6 can handle all of today’s IP-based machines and allow for future growth while handling IP addresses for mobile devices such as personal digital assistants (PDAs) and cell phones.

An IPv6 address is usually divided into groups of 16 bits, written as 4 hex digits. Hex digits include 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F. The groups are separated by colons (:). Here is an example of an IPv6 address:

FE80:0000:0000:0000:02A0:D2EF:FEA5:E9F5

Similar to IPv4, the IPv6 addresses are split in two parts, bits that identify the network and bits that define the host address. Different from IPv4, IPv6 has a fixed prefix that contains specific routing and subnet information. The first 64 bits (four groups of four hex digits) define the network address and the second 64 bits define the host address. For our FE80:0000:0000:0000:02A0:D2EF:FEA5:E9F5 address, FE80:0000:0000:0000 defines the network bits, and 02A0:D2EF:FEA5:E9F5 defines the host bits.

Most users will find the IPv4 and IPv6 addresses difficult to remember when communicating with other computers. Instead, a user specifies a recognizable name, and the name is translated into an address. For example, when a user opens Internet Explorer and specifies http://www.microsoft.com, the www.microsoft.com is translated into an IP address. The web page is then accessed from the server using the translated IP addresses.

Fully qualified domain names (FQDNs), sometimes referred to as just domain names, are used to identify computers on a TCP/IP network. Examples include the following:

One way to translate the FQDN to the IP address is to use a Domain Name System (DNS) server. DNS is a distributed database (database is contained in multiple servers) that contains the host name and IP address information for all domains on the Internet. For every domain, a single authoritative name server contains all DNS-related information about the domain. When you configure IP, you must specify the address of a DNS server so that you can use the Internet or log on to a Windows Active Directory domain.

Besides the DNS server, a HOSTS file on each machine can also be used to translate domain/host names to IP addresses. The disadvantage of using HOSTS files is that you must add entries on every machine.

If you try to access a network resource by name rather than IP address and the device cannot be found, it is most likely a problem with the DNS server/HOSTS file or the WINS server/LMHOSTS file. Either the servers cannot be contacted, or the servers or files have the wrong address associated with the name. The failure of these servers or files can also affect network applications that need to access various services or resources.

To configure the IP configuration in Windows Vista, follow these steps:

To specify IPv4 IP address settings, do one of the following:

To specify IPv6 IP address settings, do one of the following:

Windows Vista provides the capability to configure alternate IP address settings to support connecting to different networks. Although static IP addresses can be used with workstations, most workstations use dynamic or alternate IP addressing, or both. You configure dynamic and alternate addressing by completing the following steps:

To specify DNS server address settings for IPv4 and IPv6, do one of the following:

Wireless adapters can run in one of two operating modes:

The most widely used wireless network adapters and APs are based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 specification, as shown in Table 4.2. Most wireless networks used by companies are 802.11b 802.11g, or 802.11n networks. Wireless devices that are based on this specification can be Wi-Fi Certified to show they have been thoroughly tested for performance and compatibility.

Because a wireless network signal can be captured by anyone within the range of the antennas, it is easy for someone to intercept the wireless signals that are being broadcast. Therefore, it is always recommended that you use some form of encryption.

The most basic wireless encryption scheme is Wireless Equivalency Protection (WEP). With WEP, you encrypt data using 40-bit, 128-bit, 152-bit, or higher private key encryption. With WEP, all data is encrypted using a symmetric key derived from the WEP key or password before it is transmitted, and any computer that wants to read the data must be able to decrypt it using the key. However, it is easy for someone with a little knowledge or experience to break the shared key because it doesn’t change automatically over time. Therefore, it is recommended to use a higher form of wireless encryption than WEP.

Today, it is recommended to use Wi-Fi Protected Access (WPA) and Wi-Fi Protected Access Version 2 (WPA2). WPA was adopted by the Wi-Fi Alliance as an interim standard prior to the ratification of 802.11i. WPA2 is based on the official 802.11i standard and is fully backward compatible with WPA.

WPA provides strong data encryption via Temporal Key Integrity Protocol (TKIP), whereas WPA2 provides enhanced data encryption via Advanced Encryption Standard (AES), which meets the Federal Information Processing Standard (FIPS) 140-2 requirement of some government agencies. To help prevent someone from hacking the key, WPA and WPA2 rotate the keys and change the way keys are derived.

WPA-compatible and WPA2-compatible devices can operate in Personal or Enterprise mode:

In Personal mode, WPA or WPA2 uses a preshared encryption key rather than a changing encryption key. The preshared encryption key is programmed into the AP and all wireless devices, which is used as a starting point to mathematically generate session keys. The session keys are then changed regularly so that the same session key is never used twice. Because the key rotation is automatic, key management is handled in the background.

In Enterprise mode, wireless devices have two sets of keys: session keys and group keys. Session keys are unique to each association between an AP and a wireless client. They are used to create a private virtual port between the AP and the client. Group keys are shared among all clients connected to the same AP. Both sets of keys are generated dynamically and are rotated to help safeguard the integrity of keys over time. The encryption key can be supplied through a certificate or smart card.

If you click View Status for the wireless connection, you’ll see a status dialog box. You can use the Wireless Network Connection Status dialog box to check the status of the connection and to maintain the connection, in much the same way as you can for other types of connections. You’ll also see the duration and speed of the connection (see Figure 4.2).

Figure 4.2. The status of a wireless connection.

Any wireless AP broadcasting within range should be available to a computer with a wireless adapter. By default, Windows Vista is set to allow you to configure the network settings that should be used. This enables you to configure different authentication, encryption, and communication options as necessary.

If you haven’t previously connected to a wireless network, you can create a connection for the network by completing the following steps:

If you have multiple computers that need to be configured to connect to a wireless network, you can use a USB flash drive to carry the configuration from computer to computer. To save the USB information to a USB drive, follow these steps:

To add a wireless computer running Windows Vista by using a USB flash drive, follow these steps:

You might be prompted to restart the computer. If you’re previously connected to a wireless network, you can easily connect to it or disconnect from it by completing the following steps:

You can manage wireless networks using Manage Wireless Networks. To access Manage Wireless Networks, follow these steps:

Manage Wireless Networks lists wireless networks in the order in which the computer should try to use the available networks. The network listed at the top of the list is tried before any others. If the computer fails to establish a connection over this network, the next network in the list is tried, and so on.

To change the preference order of a network, click it, and then use the Move Up or Move Down buttons to set the order in which the computer should try to use the network. As necessary, click Add to create a new wireless network that will be added to the wireless networks list, or select an existing network and click Remove to delete a listed wireless network.

A dial-up connection is a nonpermanent point-to-point connection typically using a modem and a phone line to connect to

Analog modems use dedicated telephone lines to connect users to the internal network at speeds up to 33.6 kilobits per second (kbps). Digital modems use channels of an ISDN line to connect users to the internal network at speeds up to 56 kbps. Communication is controlled by a remote access server (RAS), which authenticates the login ID and password and authorizes the user to connect to the Internet or internal network.

If you are using a modem, you need to configure dialing rules so that the modem knows how the phone lines are accessed, what the caller’s area code is, and what additional features should be used when dialing connections. Sets of dialing rules are saved as dialing locations in the Phone and Modem Options tool.

To view and set the default dialing location, follow these steps:

After you configure an initial location and click OK, you‘ll see the Phone and Modem Options dialog box. To create a dial-up Internet connection to an ISP, follow these steps:

Dial-up uses a telephone line to establish connections between two modems. To establish a dial-up connection, follow these steps:

Today, many connections are broadband connections, typically using a cable or Digital Subscriber Line (DSL) connection. Because these connections are always on, you don’t need to set up dial-up rules or locations, and you don’t have to worry about ISP access numbers. Most broadband providers give users a router or modem, which users need to connect to the service provider. In most scenarios, a network adapter on the user’s computer is used to connect to the router or modem. In this configuration, the necessary connection is established over the local area network (LAN) rather than a specific broadband connection. Therefore, it is the local area connection that must be properly configured to gain access to the Internet. You won’t need to create a broadband connection.

You can, however, create a specific broadband connection if needed. In some cases, you need to do this to set specific configuration options required by the ISP, such as secure authentication, or you might want to use this technique to set the username and password required by the broadband provider.

Virtual private networking (VPN) is the creation of secured, point-to-point connections across a private network or a public network such as the Internet. A virtual private networking client uses special TCP/IP-based protocols, called tunneling protocols, to make a virtual call to a virtual port on a virtual private networking service. Encryption technology is used to secure the communication channel.

Windows Vista supports VPN tunnels that use Point-to-Point Tunneling Protocol (PPTP) for tunneling and Microsoft Point-to-Point Encryption (MPPE) for encryption. In addition, Windows Vista also supports VPN tunnels that use Layer 2 Tunneling Protocol (L2TP) for tunneling and IP security (IPSec) for encryption. The VPN client authenticates to the remote-access server, at which time they negotiate the tunneling and encryption technologies.

VPNs are used to establish secure communications channels over an existing dial-up or broadband connection. You must know the IP address or FQDN of the remote-access server to which you are connecting. If the necessary connection is available and you know the host information, you can create the connection by following these steps: