Interprocess communications (IPC) is the process of exchanging data or instructions between two computers. IPCs support two-way communications between computers. NT supplies six methods of IPC: NetBIOS, Windows Sockets, named pipes, mailslots, NetDDE, and remote procedure calls (RPC).

The Network Basic Input/Output System (NetBIOS) is a session-level interface used by applications to communicate with NetBIOS-compliant transport protocols. NetBIOS has been around since the early 1980s. Since NetBIOS has been around so long, it is now used mainly for backwards compatibility to older systems.

The NetBIOS interface is responsible for: establishing logical network names, beginning sessions between two computers, and supporting reliable data transfer between computers that have an established session. The logical network name is used to uniquely identify each computer on the network. The name is made up of 1 – 15 characters. One of the drawbacks to NetBIOS naming is that it is a flat namespace. You'll need to be careful when planning a naming convention for your network. If you use last names for computer names, you'll quickly run into problems, especially if you manage a large network, or if your network grows beyond your planned size. After a session is established, computers can communicate in the form of NetBIOS requests or in the form of Server Message Block (SMB). NetBIOS can be implemented over TCP/IP, NWLink, or NetBEUI. A NetBIOS client-server application can communicate over various protocols: NetBEUI protocol (NBF), NWLink NetBIOS (NWNBLink), and NetBIOS over TCP/IP (NetBT).

Windows Sockets (Winsock) is the windows implementation of the UC Berkeley Sockets API. Microsoft TCP/IP, NWLink, and AFP use this interface. A socket provides an endpoint to a connection. Two sockets make a complete path. The two sockets work as a bi-directional pipe for incoming and outgoing data between two computers.

Named pipes provide connection-oriented communications. This means they guarantee delivery of the data. Named pipes help client-server applications by providing a secure channel between two processes for exchanging data. Named pipes also provide for impersonation. This allows the server to process the client request in the security context of the client. Using impersonation ensures that the client's process doesn't exceed his level of permissions.

Mailslots provide connectionless communications. This means they do not guarantee delivery of data. Mailslots are generally used for broadcast messages. The browser service uses mailslots to advertise your arrival on the network.

Remote procedure calls (RPC) are the most flexible and robust of the IPC mechanisms. RPC uses other IPC mechanisms to establish communications between two computers. RPC can ride over named pipes, NetBIOS, or winsocks to communicate with other computers. An RPC can be established on the same computer as a client call to a server. It does this by using the local procedure call (LPC) to transfer information between processes and subsystems.

Network dynamic data exchange (NetDDE) allows two applications to communicate, with a link always maintained. The link must always be maintained so that when the server registers a change, all other clients receive the message of the change. MS Hearts and Chat are two examples of NetDDE.

The NetDDE IPC by default is not started. Whenever you start a NetDDE-enabled application, the NetDDE IPC automatically starts. NetDDE depends on a hidden share called NDDE$. This share maps to a DDE process, not a folder. The share is created whenever a NetDDE-enabled application is started. NetDDE provides information-sharing capabilities by opening two one-way pipes between applications.

In this section I'll take you through opening the Control Panel, adding a service, removing and reinstalling a service, installing a transport protocol, and changing the domain that your workstation participates in.

1. Right-click Network Neighborhood.
2. Select properties.

Or

1. Click Start | Settings | Control Panel.
2. Double-click the Network icon.

In exercise 7-2 we'll add Simple TCP/IP Services to your NT Workstation.

1. Open Network Control Panel.
2. Select the Services tab. You see the screen in Figure 7-6.



Figure 6: The Network properties Services tab.

3. Click the Add button. You see the screen in Figure 7-7.



Figure 7: Adding a network service.

4. Select Simple TCP/IP Services and click OK.
5. You are prompted for the location of your NT Workstation CD. Insert your CD and type in the appropriate path. Click Continue.
6. Click Close.
7. Restart your computer.

The next exercise teaches you how to remove a service, and then reinstall that same service. This is a necessary procedure when you think a service has a corrupted DLL file and you wish to fix it. Remember that, after installing new services or components to NT, you need to reinstall your latest NT service pack. The key to this exercise is step 5. After removing a service, you must restart your computer before adding that service back.

1. Open Network Control Panel.
2. Select the Services tab.
3. Select Simple TCP/IP Services.
4. Click Remove button.
5. Restart your computer.
6. Follow the steps in Exercise 7-2.

Exercise 7-4 shows you how to add NetBEUI as a protocol to your system.

1. Open Network Control Panel.
2. Select the Protocols tab.
3. Click the Add button.
4. Select NetBEUI Protocol and click OK.
5. You are prompted for the location of your NT Workstation CD. Insert your CD and type in the appropriate path. Click Continue.
6. Click Close.
7. Restart your computer.

The next exercise teaches you how to remove your computer from a workgroup and add it to a domain. For this exercise you'll need an NT server on your network configured as a domain controller. You'll also need to have administrative rights to the domain.

1. Open Network Control Panel.
2. On the Identification tab, shown in Figure 7-8, click the Change button.



Figure 8: The Identification tab in Network Properties.

3. You now see the screen in Figure 7-9. Select the Domain option button.



Figure 9: Changing the Workgroup to a Domain.

4. Enter the domain name of an NT Domain to which you have administrator rights.
5. Check-mark the Create a Computer Account in the Domain check box. (See Figure 7-10.)



Figure 10: Adding a computer account on the domain.

6. Enter your administrative username and password in the appropriate box.
7. Click OK.

The Bindings tab in Network Control Panel allows you to set the order in which protocols, adapters, and services are processed. Binding is the linking of network components on different levels to enable communication between those components. A network component can be bound to one or more network components above or below it. The services that each component provides can be shared by all the components bound to it. The higher an object is in the order, the faster it's accessed. You also can disable an adapter, a protocol, or a service at the Bindings tab. Figure 7-11 shows the Network Control Panel bindings tab.

You can view all services, all protocols, or all adapters by using the drop-down menu Show Bindings For. By clicking the + signs, you can expand the branches. Figure7-12 shows all adapters bindings expanded out for adapter [3].

In exercise 7-6 you go through the steps of changing the priority of the transport protocol. For this exercise you'll need at least two protocols installed on your workstation. This exercise assumes that you have TCP/IP and NetBEUI installed, and that NetBEUI is higher in the binding order before we start the exercise. Since all of our servers have TCP/IP as their default protocol, we want to make TCP/IP higher in the binding order.

1. Open Network Control Panel.
2. Select the Bindings tab.
3. Show Bindings for: All services.
4. Expand each branch by clicking the + symbol, as shown in Figure 7-13.



Figure 13: NetBEUI is higher in the binding order.

5. Every place you see NetBEUI Protocol, select it, then press the Move Down button.
6. Your screen should now look something like Figure 7-14.



Figure 14: TCP/IP is higher in the binding order.

7. Click OK.

Once a share is created, the best way to manage the share is through the Server applet in Control Panel. Using the Server applet you can monitor the following:

	NT bridges the gap between the OS and the NOS by providing built-in networking.
	The NT networking model is made up of layers, which loosely correspond to the seven layers of the OSI networking model.
	Be sure to understand that the TDI layer and the NDIS layer allow transport protocols to communicate with applications and networks seamlessly.
	NT uses redirectors to give client computers access to server services.
	Protocols are languages used by computers.

NetBEUI is a fast, small, and non-routable protocol.

NWLink is Microsoft's implementation of Novell's IPX/SPX protocol.

TCP/IP is the default protocol for Windows NT.

	Data Link Control (DLC) is a gateway protocol.
	Know which protocols are routable (NWLink and TCP/IP) and which ones aren't (NetBEUI and DLC). Also know when you should use each protocol in a given situation.
	IPCs support two-way communications between computers. NT supplies six methods of IPC: NetBIOS, Windows Sockets, named pipes, mailslots, NetDDE, and remote procedure calls (RPC).
	Once a share is created, the best way to manage the share is through the Server applet in Control Panel.
	NT creates hidden shares for administrative purposes. Two hidden administrative shares are the C$ and the Admin$.
	The Computer Browser service maintains a list of available servers on the network and provides that list to the clients, when requested.

Self Test

1. Which of the following are advantages to implementing the redirector as a file system driver? (Choose all that apply)

A.) It runs in Kernel mode

B.) It can load dynamically

C.) It can unload dynamically

D.) It can coexist with other redirectors

2. Which layer of the OSI model does the NDIS layer of the Microsoft Networking model operate?

A.) Session

B.) Transport

C.) Network

D.) Data Link

3. Which layer is between the TDI and the NDIS layers?

A.) Transport protocols

B.) Transport

C.) MAC

D.) Redirector

4. What does the TDI layer provide?

A.) It allows the redirector to communicate with a standard interface regardless of the transport protocols being used

B.) It allows hardware vendors to write NIC drivers without regard to the transport protocol

C.) It provides way to send data to the network without involving the application

D.) It provides networking services for remote computers

5. What is the importance of the NDIS interface layer?

A.) It allows the redirector to communicate with a standard interface regardless of the transport protocols being used

B.) Transport protocols can't be used without the NDIS layer

C.) It allows multiple NIC drivers to be loaded against the redirector

D.) Hardware vendors can write NIC drivers to access the NDIS layer without regard to the transport protocols being used

6. What does the multiple UNC provider (MUP) do?

A.) It converts mapped drives to a UNC

B.) It sends I/O requests with UNC names to the appropriate redirector

C.) It receives WNet commands, chooses the proper redirector, and passes the command to the selected redirector

D.) It allows users to have more than one UNC-connected resource open at a time

7. Which protocol could you use if you had two separate physical subnets connected by a router? (Choose all that apply)

A.) NetBEUI

B.) NWLink

C.) TCP/IP

D.) DLC

8. Which protocol would you choose if you had a LAN with only 5 workstations and 1 server connected on a single physical subnet?

A.) NetBEUI

B.) NWLink

C.) TCP/IP

D.) DLC

9. Which protocol is used mainly as a gateway protocol?

A.) NetBEUI

B.) NWLink

C.) TCP/IP

D.) DLC

10. You want to connect two remote sites with a router, but don't want to waste time configuring a protocol. Which protocol should you choose?

A.) NetBEUI

B.) NWLink

C.) TCP/IP

D.) DLC

11. You want to create a share on your workstation, but don't want it to be visible when users browse the network. How can you do this?

A.) Since it is a hidden share it is considered an administrative share; therefore, an administrator must do this

B.) Type NET CONFIG SERVER /HIDDEN:YES

C.) Create a share with $ at the end of the share name

D.) Create a virtual share using the Server applet in Control Panel

12. Which type of IPC is used when your computer broadcasts that it is joining a workgroup?

A.) Mailslots

B.) RPC

C.) Named pipes

D.) NetBIOS

13. Your workstation has NetBEUI, NWLink, and TCP/IP installed on it. You notice that every time you browse the network, your computer takes a long time to display the available computer's list. Your friend doesn't experience any noticeable delay when browsing the network. What should you do to fix the problem? (Choose all that apply)

A.) Remove all unnecessary protocols

B.) Remove NetBEUI

C.) Adjust the binding order to put the most-used protocol higher in the binding order

D.) Set a protocol standard using only one protocol, install that protocol on all machines, and remove all other protocols

14. You have several folders shared on the network from your workstation. How can you check to see which folders have connections to them?

A.) Use the Server applet in Control Panel and select the Users button

B.) Enable auditing of the all shared folders

C.) Use network monitor to identify all user connections

D.) Use the Server applet in Control Panel and select the Alerts button. Set an alert to tell you whenever people access your shares.

15. Which service allows your computer to be seen on the network?

A.) Messenger

B.) Server

C.) Workstation

D.) Computer Browser

16. You are developing a NetBIOS-compliant naming standard for your organization. You plan to use the following format: CityName-Bldg#-Rm#-FirstName. The cities where your network is installed are Dallas, Los Angeles, New York, and Orlando. Building numbers are all four digits and room numbers are all three digits. No one's first name is over ten characters in length. Will this work?

A.) Yes

B.) No