When you begin using TCP/IP on your network, you can configure your workstations by visiting each and every one—or you can specify the information at one place and have the workstations get what they need without your having to make all those visits. The genie in the bottle for this solution is known as Dynamic Host Configuration Protocol (DHCP).
As with DNS services, you can run multiple DHCP servers. However, you have to establish a different pool of addresses for each DHCP server. That way, you don’t run the risk of having more than one DHCP server assign the same IP address to several workstations. In this Daily Drill Down, I’ll walk you through the process of installing and configuring DHCP services on your NetWare 5 server.
Installing DHCP services
You have three options for installing DHCP services on NetWare 5:
- Install during the initial NetWare 5 server installation
- Install with the NetWare installation program from the NetWare GUI
- Run DNIPINST.NLM
For the purposes of this drill down, I’ll assume that you have NetWare 5 up and running and you’ll use DNIPINST.NLM to install the DHCP service. In the NetWare 5 Console window, type DNIPINST and press [Enter]. In the Novell DNS/DHCP Services Setup window, verify that the fully qualified NDS username—with appropriate rights to modify the NDS tree—is specified. Enter the password for this user and press [Enter] to log this NLM into the NDS tree. You’ll see a series of messages as the NDS schema is extended in order to enable it to provide the DHCP service.
When this process is complete, the NDS Context Query Form will ask you to position the Locator, Group, and RootServerInfo Zone objects in your NDS tree. The Locator object holds the global defaults, a list of DNS servers, subnets, and zones in your tree. The Group object provides a means of obtaining information about any DNS-related object on the tree. The RootServerInfo Zone object points to the root DNS servers on the Internet. It enables you to obtain information about domains that you don’t maintain in your NDS tree when you’re using DNS services on NetWare 5. Although you’re more concerned with DHCP than with DNS services, you must act like you’re installing a DNS, as well, because Novell has merged both services into one installation routine.
After verifying that the correct NDS contexts are specified (in my tree, I have only one context, NW5, so all the data input fields show O=NW5), highlight the Press Enter To Create The Objects option and press [Enter]. A series of messages will appear as the installation routing creates the DNS and DHCP objects. Then, you’ll see a message telling you that you can run the Java-based DNS/DHCP Management Console to configure the DHCP service that you’ve just installed. Press [Enter] to return to the NetWare 5 Console window.
The next step is to install the DNS/DHCP Management Console. Move to the SYS:PUBLIC\DNSDHCP directory and run SETUP.EXE. Doing so installs the DNS/DHCP Management Console to the local hard drive of the workstation that’s running the Setup program. This program installs the necessary snap-ins so that NWADMIN can run the console. When installing the snap-ins, you may have to browse to find the path for the files. If the destination window shows no directory path for NWADMIN, provide this path, and the snap-ins will work correctly. If any read-only files are detected, tell the Setup program to overwrite those files. If you don’t overwrite them, the DNS/DHCP Management Console may not operate properly. When you’ve finished, click Next.
Take a few minutes to review the readme file. This file contains information for configuring the server properly or resolving problems. After you read the file, close Notepad, and you’ll see a message that the DNS/DHCP Management Console setup is complete. Click OK to continue. You should reboot your workstation after the management console has been installed.
Configuring the DHCP service
Five NDS objects are associated with the DHCP services:
- DHCP Server
- DHCP Subnet
- Subnet Address Range
- IP Address
- Subnet Pool
The DHCP Server object provides the foundation for DHCP services by specifying the server(s) that will provide DHCP services to the clients. The DNS/DHCP Management Console creates the DHCP Subnet object for each range of IP network addresses that the DHCP service provides. You can use subnets to send configuration information (such as DNS server and gateway information) to the workstations in addition to their IP address. The Subnet Address Range object contains the starting and ending IP addresses from the range that you want available for the workstations on a particular segment. The IP Address Object is used when you want a particular address to be assigned only to a particular host and you don’t want to configure that device with the required information. The Subnet Pool object will be used only if you have several IP network addresses in use on a particular segment.
To configure the DNS servers on your NetWare 5 server, you can use the DNSDHCP Java application that you’ll see on the desktop after you reboot the workstation. Or you can use NWADMIN. Select DNS-DHCP Management Console from the Tools menu to start the configuration process. Either option takes you to the same place. If you use the desktop Java application, specify the context of the NDS tree with which it will be working. If you use NWADMIN, that information is passed automatically to the Java application when it’s called by NWADMIN.
First, you’ll need to create a DHCP Server object. This object designates a server in your tree that can respond to DHCP requests from the workstations. Start the DNS/DHCP Management Console and click the DHCP Service tab. Click the Create button on the toolbar to open the Create New DHCP Record window. Highlight DHCP Server and click OK. When the Create DHCP Server window appears, use the Browse button to the right of the Select Server Object field to browse the NDS tree. Select the server that you want to use as the DHCP server and click OK. In the Create DHCP Server window, click Create to finish creating the DHCP Server object. When the server object has been created, an icon appears at the bottom of the DNS/DHCP Management Console window. The icon will have an X through it until you start the DHCP service on the server.
Next, you must create a DHCP Subnet object. This object represents the IP network address assigned to the IP segment where the server that will provide the DHCP services resides. Click the Our Network button, click Create, highlight the Subnet option, and click OK. When the Create Subnet Object window appears, enter the name for this subnet. Each subnet object that you create for the DHCP server will have a unique name in NDS. The NDS context for this subnet should be entered already. Verify that the context is correct and make any necessary changes. Enter the subnet address and subnet mask for this segment. The field containing the default DHCP server for this segment should be filled in already. If you have two or more DHCP servers, make sure that the correct server name appears in this box. Click Create to create the Subnet object in your NDS tree.
To verify that the object has been created, click the DHCP Server Object button. It refreshes the information you just created. Now, click the Our Network button. In the Subnets Serviced By This Server field, you should see the subject object you just created. The default lease on an IP address assigned by the DHCP server is three days and 0 hours. In most cases, the default is fine. On the other hand, if you’re running short of addresses and can’t increase the range of available addresses, a shorter lease time will make the “sharing” of addresses a little easier to do. Once this object has been created, create a Subnet Address Range Object so that the DHCP server will know the range of IP addresses that it can assign to requesting workstations.
Next, you’ll create the Subnet Address Range object. Double-click the Our Network button until you see the DHCP Subnet object you created. You’ll see the network address you created (for example, 10.0.0.0), followed by the NDS name that you entered for it. Highlight the DHCP Subnet object and click Create on the toolbar in the DNS/DHCP Management Console window. In the Create New DHCP Record window, select the option Subnet Address Range. Then, click OK.
When the Create Subnet Address Range window appears, go to the Subnet Address Range Name field and enter the name by which you want this object known in NDS. Below this field, you’ll see two rows of numbers. The first row is labeled Start Address. The second row, though not labeled, is the stop address, or the last address that can be assigned by the DHCP server before it exhausts the available addresses in the pool. After you’ve entered the range of addresses that you want issued by the DHCP server, click Create to return to the main DNS/DHCP Management Console window. An additional object should appear on the left side of the window and display the starting and ending addresses that you want the server to assign.
Importing a DHCP database
If you’ve already been using the DHCP server that was available for NetWare 4.11 or if you’re migrating from another DHCP Server, you don’t have to re-create the DHCP setup when you move between servers. After you export the DHCP database into the DHCP 2.0 or 3.0 file format, import the information into the DNS/DHCP Management Console by clicking the Import DHCP Database button on the toolbar. Once the list has been read, you should see an Import DHCP Subnet List window that lists each subnet that has been read from the file. Select the NDS context where you want the subnets placed and click the Import button to finish the task.
Starting DHCP services
At this point, you’ve created the minimum number of objects necessary to provide DHCP services on your network. Now, go to the Server console command prompt window or establish an Rconsole session to that window on the server that will run the DHCP service. To start the service, type DHCPSRVR at the console prompt. Two NLMs will load—DHCPSRVR.NLM and IPCLINFO.NLM. You also should see several messages indicating that the IP database is loaded and that the DHCP Server is ready. Now, you can proceed to a workstation and reboot it to see if it obtains an address from the DHCP server.
Ronald Nutter is a senior systems engineer in Lexington, KY. He's an MCSE, Novell Master CNE, and Compaq ASE. Ron has worked with networks ranging in size from single servers to multiserver/multi-OS setups, including NetWare, Windows NT, AS/400, 3090, and UNIX. He's also the help desk editor for Network World. If you’d like to contact Ron, send him an e-mail . (Because of the large volume of e-mail that he receives, it's impossible for him to respond to every message. However, he does read them all.)The authors and editors have taken care in preparation of the content contained herein, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.