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This chapter is from the book

This chapter is from the book

Lab 2: Services and nbtstat

Orientation

In this lab you will identify how clients connect to network resources and the main services that they use. You will cover the following:

  • nbtstat

  • The two main services in networking

  • Prepare for the Network+ subdomain 3.2

Procedure

  1. Identify services with nbtstat (NetBIOS over TCP/IP Statistics).

    1. Access PC1. Make sure you are logged on as Administrator to the domain. You can verify this quickly by pressing Ctrl+Alt+Del.

    2. Open the command prompt and type nbtstat /?. This should give you a list of options with the nbtstat command. These include –a for accessing by NetBIOS names and –A for accessing by IP address. Try to memorize these different switches.

    3. Type nbtstat –a pc1. This reveals information like that shown in Figure 3.14.

    4. Figure 3.14

      Figure 3.14 nbtstat in action.

    5. Notice the different line items. You have <00>, which is the hexadecimal ID for the Workstation service. You also have <03>, the ID for the Messenger service. Finally, you have the <20> ID for the Server service. These are the three basic services that all computers, servers and clients alike, use to transmit data across the network. There are others listed that deal with the domain. If one of the services is not listed, then you know that you will have to troubleshoot the system in question. It could have to do with what network the user logged in to, TCP/IP issues, or file corruption. Or it could be that the service is shut off. Let's take a look at the three main services from a graphical standpoint and show how they can be turned on and off.

    6. Right-click My Computer and select Manage.

    7. In the bottom-left area, click the plus (+) sign to expand the Services and Applications category.

    8. Click the Services applet, as shown in Figure 3.15. Then select the Messenger service on the right side.

    9. Figure 3.15

      Figure 3.15 The Services window.

    10. Although the Messenger service is very important to the system, it is not really considered one of the main services. This is because it is actually dependent on the Workstation service. Let's prove this now.

      1. Right-click the Messenger service and select Properties.

      2. Click the Dependencies tab. You will see that the Messenger service is indeed dependent on the Workstation service.

      3. Click the General tab. Notice that here you can start and stop the service as you see fit, as well as set how it will run at startup (or set it to not run at all).

      4. Close the Properties dialog box, but leave the Computer Management window open.

      5. There are several other ways to start and stop a service in the GUI and in the command prompt. For example, you can use the buttons at the top of the console window, as shown in Figure 3.16. You can also right-click the service and select Start/Stop, or you can use the net start and net stop commands in the command prompt.

    Figure 3.16

    Figure 3.16 Start and stop buttons for services.

  2. Identify the two main services, Server and Workstation. The Server service runs on every networked computer regardless of whether it is a client or a server. It allows the computer to share resources with other systems. The Workstation service also runs on both types of systems but does the converse, allowing your computer to access resources that have been shared on other systems.

    1. You should still be in the Services section of the Computer Management console. Scroll down until you find the Server service.

    2. Right-click the Server service and select Properties.

    3. In the Server Properties dialog box, click the Dependencies tab, as shown in Figure 3.17. Notice that there are no services on which the Server service is dependent. That's because the Server service is considered a foundation service; everything else builds from it.

    4. Let's take a look at the basis for this service, the srv.sys file.

      1. Click the Start button, choose Search, and select Files or Folders.

      2. Search for srv.sys. Make sure to search your entire C drive. You should get results like the ones shown in Figure 3.18. That one system file is the basis for the Server service, and for all of the services that depend on it!

      Figure 3.17

      Figure 3.17 The Server service.

      Figure 3.18

      Figure 3.18 Srv.sys search results.

    5. Microsoft calls the other main service the Workstation service. This service allows your computer to connect to other systems' shares. However, most other platforms call it the Redirector. The system file that controls this service is known as nwrdr.sys. That stands for NetWare Redirector. Search a second time, this time for nwrdr.sys. You should get three results. One is the main service file, and the others are either backups or cache files.

    6. Return to the Computer Management window and scroll down to the Workstation service.

    7. Right-click the Workstation service and select Properties.

    8. Click the Dependencies tab. You should get results like those shown in Figure 3.19.

    9. Figure 3.19

      Figure 3.19 The Workstation service.

    10. Notice that, like the Server service, the Workstation service is not dependent on any other services, yet many other services are dependent on it! This is often a trouble point for client computers because the Workstation service is a target of attack for malicious users, and is also easily corruptible. There are a few other reasons why this service might be stopped; what you must remember is how to check whether it's running. This is done remotely with the nbtstat command.

Services are the underlying building blocks of networking within the operating system, so you must be fluent with them. Be sure to know them for the Network+ exam.

What Did I Just Learn?

In this lab you identified how clients connect to network resources and the main services that they use. Specifically, you learned the following:

  • How to correctly read a set of nbtstat results.

  • The two main services in networking.

  • How to troubleshoot services.

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