Configuring TCP/IP on Windows Workstations Networking

Being able to configure your operating system to use TCP/IP is a must for any network administrator. Because Microsoft Windows is the dominant operating system, we will show you how to configure a Windows client to use TCP/IP.

To begin configuring TCP/IP, follow these steps:

  1. Choose Start _ Settings _ Control Panel _ Network and Dial-Up Connections to open the Network and Dial-Up Connections dialog box, which lists all of the currently installed network components.
  2. Right-click one of your network adapters and select Properties to open the Properties dialog box for your adapter.
  3. If you do not see Internet Protocol (TCP/IP) in the scrolling list (assuming you have enough entries to scroll), follow the next three steps. If you do see it, skip to step 7.
  4. Configuring TCP/IP on Windows Workstations

  5. Click the Install button, which brings up the Select Network Component Type window.
  6. Configuring TCP/IP on Windows Workstations

  7. Click Protocol in the list and click the Add button to bring up the Select Network Protocol dialog box.
  8. Select Microsoft from the left frame and Internet Protocol (TCP/IP) from the right frame and click the OK button. This will take you back to the Properties dialog box for your adapter. Now Internet Protocol (TCP/IP) should appear in the scrolling list.
  9. Click Internet Protocol (TCP/IP) and click the Properties button, which brings up the Internet
  10. Configuring TCP/IP on Windows Workstations

  11. Initially, you see the General tab, which is set to obtain your IP address, subnet mask, default gateway, and DNS server(s) via DHCP. You may select the alternate radio buttons to manually enter this information.
  12. Click the Advanced button, which brings up the Advanced TCP/IP Settings dialog box.
  13. Notice the IP Settings, DNS, WINS, and Options tabs along the top of the Advanced TCP/IP Settings dialog box In the following sections, we will look at these four tabs. In addition, we will cover key information regarding the configuration database of Windows, known as the Registry, and the open set of protocols, known as ZeroConf, designed to reduce the amount of manual TCP/IP configuration necessary to bring up a small network.

The IP Settings Tab

The IP Settings tab, is to specify, edit, or remove additional IP addresses for this device when you are not using DHCP. This can be helpful when the device is acting as more than one type of server. Using an IP address for each type of server aids in clarity during configuration and troubleshooting. Additionally, you can make the same kinds of adjustments to the statically configured default gateway(s). The interface metric can be used to cause the device to favor one interface over another for otherwise equivalent routes. This is most helpful when the device is acting as a router with multiple NIC cards and possibly a dynamic routing protocol (such as RIP or OSPF) running.

The IP Settings Tab

The DNS Tab

You use the DNS tab, shown in Figure 3.8, to add, edit, or remove DNS server addresses and adjust the order in which they will be queried. You also have quite a bit of granularity with how you can control the use of DNS suffixes, which refer to the part of FQDNs that should be used when you’re trying to resolve a name to an IP address and the entered name alone does not produce a match. Dynamic DNS settings are adjusted in this tab as well.

An FQDN consists of the name of the host followed by the domain name. For example, if the name of the local computer is wallaby and the domain is sybex.com, the FQDN is wallaby.sybex.com.

The WINS Tab

By adding the IP addresses of WINS servers in the WINS tab, you specify that those servers be used in order to resolve a NetBIOS name to an IP address. The order can be adjusted after address entry.

The WINS Tab

The WINS Tab of the advanced TCP/IP settings dialog box

On this tab, you can enable the use of the local LMHOSTS file in the %SystemRoot%system32 driversetc folder of the Windows 2000 family of operating systems. You can also make choices concerning the use of NetBIOS over TCP/IP.

The Options Tab

The Options tab allows you to adjust IP security and TCP/IP filtering settings.

The Options tab of the Advanced TCP/IP settings dialog box

Highlighting the IP Security option and clicking the Properties button leads to the ability to turnoff IPSec functionality or set it to one of three modes of varying aggressiveness, beginning with simply responding to requests for IP security, then progressing to requesting IP security,and finally to requiring it.

The TCP/IP filtering option allows you to exercise quite a bit of control over which protocolsare allowed to communicate with the computer. Filtering may be performed on any combinationof TCP and UDP port numbers and IP protocol number.

The Windows Registry

All of this TCP/IP configuration information is stored in the Windows Registry database, along with lots of other hardware and software configuration information. You can change most of the TCP/IP parameters by using the Network applet in Control Panel as you have just seen. Certain parameters, however, such as Time to Live and the default Type of Service, can be changed only by using the Registry Editor (regedit.exe or regedit32, depending on your preference). If you change some of these Registry parameters without detailed knowledge of TCP/IP configuration, you may affect the performance of TCP/IP on your system in an adverse and unexpected way.

Zero Configuration (ZeroConf)

As anyone who’s ever tried to hook their laptop to someone else’s to use TCP/IP to play video games, transfer files, or whatever, will tell you…it’s a pain. Even though computer manufacturer’s and software programmers will tell you that networking is supposed to be simple, it really isn’t. You need to configure several parameters (IP address, DNS or host name, etc.) properly or you won’t be able to communicate. These parameters are usually no problem for network technicians, but what about the average person? Configuring peer-to-peer or small network networking usually involves a game of “What should my IP address be?” between the people that want to network.

Enter the Internet Engineering Task Force (IETF) and the Zero Configuration (ZeroConf) initiative. The primary goal was to make networking via TCP/IP extremely easy and “hands off” for small networks. Ideally, two computers could be connected through Ethernet jacks with only a crossover cable and be able tocommunicate without any further configuration. In order to accomplish this, the ZeroConf working group of the IETF had four main areas of focus:

  1. Automatic Interface address configuration
  2. Automatic Multicast address configuration
  3. Translation of addresses to names and names to addresses
  4. Service location

In order for the ZeroConf initiative to be successful, each of these components must be implemented in the ZeroConf protocol.

Automatic Local Interface Configuration

As you know, a computer must have a local IP address in order to communicate. Instead of relying on static addressing (too much work and too much to know) or dynamic addressing (other hardware required), ZeroConf allows for automatic configuration by the two communicating entities themselves. In the absence of a manually configured address or a DHCP server, the communicating entities will “figure out” their own local IP addresses (known as linklocaladdresses) as follows: First, for each interface, each computer chooses a random TCP/IP address somewhere in the address space 169.254.1.0 to 169.254.254.255 (that is 169.254.0.0/ 16 with the top and bottom 256 addresses reserved for future use). Then, the computer configures its local interface with this address.

Of course, it wouldn’t do any good if both computers chose the same address. So, two things happen to prevent that. First of all, the random number used to select the IP address is based on several computer-specific items (including the MAC address, real time clock, etc.) so that each computer is guaranteed a unique address. In addition, after the unique address is selected, it must be tested to ensure that no other device is using the same link-local address. To do this, the computer uses ARP to tell the other computers on the network segment connected to the interface being configured what IP address it intends to use. If no devices respond that they are already using that address, the interface is configured with the chosen address and communication can take place.

Multicast Address Selection

Another requirement of the ZeroConf initiative is that there is a mechanism for automatically choosing multicast addresses for the network. The IETF has defined the standard for the Zero-Conf Multicast Address Allocation Protocol (ZMAAP). This protocol is used to allocate multicast addresses among the various peers in small, peer-to-peer networks.

This protocol is the polar opposite of the multicast address assignment protocol known as MADCAP, which stands for Multicast Address Dynamic Client Allocation Protocol. Where MADCAP is a client-server multicast address allocation scheme, ZMAAP is a peer-to-peer allocation scheme. Essentially, each node on a ZeroConf network is running its own little multicast allocation service (called a mini-MAAS in ZeroConf parlance). Any entity that needs a multicast address will make a request to its local mini-MAAS, which will then select an address and, before permanently allocating it, inform the other local mini-MAASs of its choice. If there are any objections, the originating mini-MAAS will rechoose the address. Otherwise, it will go ahead and allocate the address.

Name Resolution

You might think that there isn’t a way around name resolution, apart from constantly exchanging HOSTS files or some other silliness. In actuality, ZeroConf relies on standard TCP/IP protocols, including one known as Multicast DNS. Traditional DNS relies on centralized servers to answer DNS queries. But the addresses of these servers must be configured (and the goal is zero configuration), so the designers of ZeroConf decided to use Multicast DNS. Multicast DNS was a little-used protocol until ZeroConf came along.

Traditional name resolution works much like asking the host at a party to introduce you to the people in the party you don’t know. Let’s say you wanted to know which person in the room was named John. With the traditional DNS model, you would ask the party host (the “DNS server” in our scenario). If you were to use Multicast DNS in the same scenario, you would simply shout in the room, “Hey, is there a John in here?”

Multicast DNS essentially puts out a multicast transmission that asks for the address of the network name being requested. This works great in small networks, but the amount of traffic required and the introduced delays make Multicast DNS impractical for larger networks, such as the Internet.

Service Location

The final aspect of ZeroConf is service location. It is important on networks to be able to locate services. AppleTalk is the master of finding services on a network without configuration. Apple designed it so that whenever you plugged a printer into an AppleTalk network, it would advertise itself on the network and you could just choose it. This traditionally has been difficult on TCP/IP networks. Furthermore, the chatty nature of such services would not be welcome on large networks.

The IETF has designed a protocol specifically for locating services on a ZeroConf network. That protocol is known as DNS Service Discovery, or DNS-SD. DNS-SD allows clients to use regular DNS queries, without the need for a new DNS message structure, to find a list of names of particular types of services provided within a particular domain.


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