Chapter 17

Troubleshooting DHCP (Reference)

This chapter provides information to help you solve problems that you might encounter when you configure a DHCP server or client. The chapter also helps you with problems you might have in using DHCP after configuration is complete.

The chapter includes the following information:

See Chapter 14, Configuring the DHCP Service (Tasks) for information about configuring your DHCP server. SeeEnabling and Disabling a Solaris DHCP Client for information about configuring your DHCP client.

Troubleshooting DHCP Server Problems

The problems that you might encounter when you configure the server fall into the following categories:

NIS+ Problems and the DHCP Data Store

If you use NIS+ as the DHCP data store, problems that you might encounter can be categorized as follows:

Cannot Select NIS+ as the DHCP Data Store

If you try to use NIS+ as your data store, DHCP Manager might not offer NIS+ as a choice for the data store. If you use the dhcpconfig command, you might see a message stating that NIS+ does not appear to be installed and running. Both these symptoms mean that NIS+ has not been configured for this server, although NIS+ might be in use on the network. Before you can select NIS+ as a data store, the server system must be configured as an NIS+ client.

Before you set up the DHCP server system as an NIS+ client, the following statements must be true:

The domain must have already been configured.
The NIS+ domain's master server must be running.
The master server's tables must be populated.
The hosts table must have an entry for the new client system, the DHCP server system.

"Setting Up NIS+ Client Machines" in System Administration Guide: Naming and Directory Services (NIS+) provides detailed information about configuring an NIS+ client.

NIS+ Is Not Adequately Configured for DHCP Data Store

After you successfully use NIS+ with DHCP, you might encounter errors if changes are made to NIS+. The changes could introduce configuration problems. Use the following explanations of problems and solutions to help you determine the cause of configuration problems.

Problem: Root object does not exist in the NIS+ domain.

Solution: Type the following command:

/usr/lib/nis/nisstat

This command displays statistics for the domain. If the root object does not exist, no statistics are returned.

Set up the NIS+ domain using the System Administration Guide: Naming and Directory Services (NIS+).

Problem: NIS+ is not used for passwd and publickey information.

Solution: Type the following command to view the configuration file for the name service switch:

cat /etc/nsswitch.conf

Check the passwd and publickey entries for the "nisplus" keyword. Refer to the System Administration Guide: Naming and Directory Services (NIS+) for information about configuring the name service switch.

Problem: The domain name is empty.

Solution: Type the following command:

domainname

If the command lists an empty string, no domain name has been set for the domain. Use local files for your data store, or set up an NIS+ domain for your network. Refer to the System Administration Guide: Naming and Directory Services (NIS+).

Problem: The NIS_COLD_START file does not exist.

Solution: Type the following command on the server system to determine if the file exists:

cat /var/nis/NIS_COLD_START

Use local files for your data store, or create an NIS+ client. Refer to the System Administration Guide: Naming and Directory Services (NIS+).

NIS+ Access Problems for the DHCP Data Store

NIS+ access problems might cause error messages about incorrect DES credentials, or inadequate permissions to update NIS+ objects or tables. Use the following explanations of problems and solutions to determine the cause of NIS+ access errors you receive.

Problem: The DHCP server system does not have create access to the org_dir object in the NIS+ domain.

Solution: Type the following command:

nisls -ld org_dir

The access rights are listed in the form r---rmcdrmcdr---, where the permissions apply respectively to nobody, owner, group, and world. The owner of the object is listed next.

Normally, the org_dir directory object provides full rights to both the owner and the group. Full rights consist of read, modify, create, and destroy. The org_dir directory object provides only read access to the world and nobody classes.

The DHCP server name must either be listed as the owner of the org_dir object, or be listed as a principal in the group. The group must have create access. List the group with the command:

nisls -ldg org_dir

Use the nischmod command to change the permissions for org_dir if necessary. For example, to add create access to the group, you would type the following command:

nischmod g+c org_dir

See the nischmod(1) man page for more information.

Problem: The DHCP server does not have access rights to create a table under the org_dir object.

Usually, this problem means the server system's principal name is not a member of the owning group for the org_dir object, or no owning group exists.

Solution: Type this command to find the owning group name:

niscat -o org_dir

Look for a line that is similar to:

Group : "admin.example.com."

List the principal names in the group using the command:

nisgrpadm -l groupname

For example, this command lists the principal names of the group admin.example.com:

nisgrpadm -l admin.example.com