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TCP/IP and Data Communications Administration Guide

Chapter 17 Troubleshooting DHCP

This chapter describes how to troubleshoot problems you may encounter while using DHCP. It includes solutions to problems you may have when installing and configuring the first DHCP server. To further help you troubleshoot server problems, this chapter also includes background information about the DHCP server configuration script (dhcpconfig) - the purpose of various script components and how the script executes installation procedures. It also describes problems you may encounter as you add your first and subsequent DHCP clients to the network.

Strategies and Tips

The following troubleshooting techniques are helpful in solving problems when you cannot isolate the cause:

This chapter describes these techniques in more detail. It also tells you where to get more information when you cannot solve a problem using this guide.

Using snoop to Monitor Network Traffic

You can use the snoop command to monitor network traffic.

To Use snoop to Monitor Network Traffic

  1. Log in to the root account on a Solaris server or BOOTP/DHCP relay agent on the same subnet as the client.

  2. Use the snoop command to trace network traffic. For example: 


    snoop -o /tmp/output udp port 67 or udp port 68

  3. Boot the client and watch the DHCP message exchange between the client and server(s).

  4. Type: 


    snoop -i /tmp/output -x 0 -v

You can limit the scope of snoop by specifying the client's hardware address. A version of snoop that understands the DHCP/BOOTP protocols is available in Solaris version 2.5 and later.

Running the DHCP Client in Debug Mode

Running the DHCP client in debug mode reveals much of the ongoing dialogue between the client and the server. Refer to the documentation for the product on which you are running the client.

To Run a Solaris 2 Client in Debug Mode

Debugging the DHCP client is only possible after it has booted. If DHCP problems are experienced, you must boot with DHCP disabled. The steps here can be performed only once after the host has booted, preferably in single-user mode.

  1. The DHCP agent can be configured to log details of the packets exchanged with the server. To do this, the agent must be started with debug mode turned on: 


    /sbin/dhcpagent -n -d3 &

    The -d3 flag turns on debug at leve1 3, and the -n flag says "don't configure the interface even if DHCP is successful".

    Note -

    Level 3 and levels below that return appropriate information for the user. Levels above level 3 are appropriate only for developers or those with even more expertise, since they return raw packets of information.

  2. Only one instance of dhcpagent can run at a time, so before the agent can be started in this manner, any previously invoked agent must be stopped. To do this, find the agent's process ID and send it the terminate signal: 


    kill -TERM process_id_of_dhcpagent

  3. After an agent has been started in debug mode, try to configure an interface manually by typing: 


    ifconfig interface_name auto_dhcp

    The packets that are sent, and any that are received, will be displayed.

    Note -

    During the time that DHCP tries to configure an interface, the interface is unable to send or receive packets. Other network services, such as NIS or NFS, may be adversely affected while the interface is down.

To Run the DHCP Server in Debug Mode

    Stop and restart the DHCP server in debug mode.

For example:

  1. Stop the server using the shutdown script: 


    /etc/init.d/dhcp stop

  2. Restart the server in debug/verbose mode, using the -d and -v flags in addition to any flags specified in the /etc/init.d/dhcp startup script. For example, if the i option is present, type the command in the following format: 


    /usr/lib/inet/in.dhcpd -i interface_names  -d -v

Restarting the DHCP Client

Once you have run the DHCP client in debug mode, you can try rebooting. Rebooting resets the network hardware and software.

To Restart the DHCP Client

  1. Reboot the client.

To Restart the DHCP Server

  1. Log in to the DHCP server as root.

  2. Type: 


    /etc/init.d/dhcp stop

    Wait about 10 seconds.

  3. Type: 


    /etc/init.d/dhcp start

To Restart the DHCP Server After Debugging is Completed

  1. Restart the DHCP server daemons.

  2. Log in to the DHCP server as root.

  3. Type: 


    /etc/init.d/dhcp stop

    Wait about 10 seconds.

  4. Type: 


    /etc/init.d/dhcp start

Common Problems

This section describes some of the more common problems you may encounter with DHCP, and what to do about them.

Problem

The DHCP client is sending out DHCPDISCOVER or DHCPREQUEST messages, but the DHCP server is not responding.

Verification: Check the server machine's console. It may not have any IP addresses left to allocate.

Solution: Add more IP addresses.

Verification: Check the server machine's console. If the server is stating that the client is unrecognized, then the DHCP server's databases may have been flushed, with the result that the server fails to recognize the client.

Solution: Remove any DHCP cache file on the client.

  1. Interrupt the boot by typing Control -C.

  2. Remove the cache by typing:


    cd /etc/dhcp;  
rm interface_name.dhc

  3. Restart the initialization process by typing 


    ifconfig interface_name dhcp release

Verification: Check the server machine's console. Perhaps support for the client's network has not been added to the DHCP databases.

Solution: Add support for the client's network, using dhcpconfig.

Verification: The client is on a network separate from that of the DHCP server, and a BOOTP relay agent has not been installed or configured.

Solution: Install and configure a BOOTP relay agent. In addition, you may need to add an entry to the netmasks(4) database for the remote network.

Problem

The client logs a message that the address is already in use.

Verification: Check whether the address is in use elsewhere. If the client continues to log the same message, it is likely that the server is not checking the address, or is ignoring the client's message which declines the address. Check to be sure you are not using the in.dhcpd command with the n option.

Solution: Find out whether the server gave out the bad address. Either the server is malfunctioning, or another user has illicitly used the same address.

Problem

The following error message is displayed:


DHCP renewal on interface_name failed

Verification: The DHCP client was unable to renew a lease on the specified interface.

Solution: Make sure that the DHCP server is still running correctly.

Problem

The following message is displayed:


Address of interface name has changed

Verification: The address or status of the interface is not what the DHCP agent expects to see. The address was probably altered manually.

Solution: There is no solution. The agent will stop trying to configure the interface.

Where to Get More Help

If after using these instructions you need further assistance, please call your local Solaris sales or service representative. To ensure that you receive the best possible service, have the following information ready before calling for help.

Troubleshooting the DHCP Server

This section discusses problems you may have with your DHCP server.

When Using Files

Follow the instructions below if you have problems while using files as a name service.

Problem

You cannot access the /var/dhcp directory; it either does not exist or you do not have UNIX file permissions to read it.

Verification: Use the following command: 


ls -d /var/dhcp

Solution: The DHCP server hasn't yet been configured. Run dhcpconfig.

When Using NIS+

Follow the instructions below if you have problems while using NIS+ as a name service.

Problem

The root object does not exist in the NIS+ domain.

Verification: Enter the command: 


niscat -o org_dir

Solution: Refer to Solaris NIS+ setup documentation.

Problem

The root account does not have access rights to create a table under the org_dir object.

Verification: Enter the command:


niscat -o org_dir

Solution: Use the nischmod command to change the permissions on the table.org_dir.domainname.

Problem

The root account does not have access rights to create a table under the org_dir object. Usually, this means the root account's principal name is not a member of the owning group for the org_dir object, or no owning group exists.

Verification: Enter this command to find the owning group name: niscat -o org_dir

Solution:

  1. Enter nisgrpadm -l group to see the group members.

  2. If the current system's principal name is not in the group, enter: nisgrpadm -a group principalname to add it. Typically, the group is admin. If it is not, edit the dhcpconfig script and change the group to match the group name in use.

  3. Enter /usr/lib/nis/nisctl -fg to flush the cache for immediate update.

Problem

The domain name is unset.

Verification: Enter the command:


domainname

If the command lists an empty string, no domain name has been set for the domain.

Solution: Use the domainname command to set the proper domain name. Place the domain name value in the /etc/default domain.

Problem

The NIS_COLD_START file does not exist.

Verification: Enter the following command on the server system:


strings /var/nis/NIS_COLD_START

Solution: Create a NIS+ client. Refer to the Solaris NIS+ QuickStart documentation.

Problem

You choose NIS+ and the site is not running NIS+.

Verification: Log on to the server. Type in the command:


 ps -ef | grep nis

If NIS+ is running you will see output similar to: /usr/sbin/rpc.nisd -YB.

Solution: Create a NIS+ server:

  1. On the client, set up the NIS+ root master server for the domain. For example:


    /usr/lib/nis/nisserve -r

  2. Populate the NIS+ tables from the local /etc files. For example:


    nispopulate -F /etc

  3. On the server, verify that NIS+ is running. For example:


    /usr/lib/nis/nisstat
nisls org_dir  
niscat hosts.org_dir

Cannot Use NIS+ as Name Service

One or more of the following error messages are displayed:


!!! warning !!! trailing dot ignored - use dns domain name syntax


Error 20 from NIS+; unable to use NIS+ as name service.

These messages mean either that there is no such name in the NIS+ domain, or the NIS+ domain does not exist. Use the information below to find and solve errors in the configuration of NIS+.

Problem

The domain name for the server system ends with a period.

Verification: Enter the nisdefaults command to determine whether there are two trailing periods after the domain name.

Solution:

  1. Edit the /etc/defaultdomain file by removing the trailing period (.) from the domain name.

  2. Reboot your system, and rerun the dhcpconfig script.

Problem

A host name includes the domain name. For example, setting a host to myhost.Faxco.COM instead of myhost.

Verification: Enter the nisdefaults command to show a host name with the domain name included twice.

Solution:

  1. If your host name is set incorrectly, enter the sys-unconfig command to remove the configuration settings and halt the system.

  2. Reboot the system and supply the correct settings for host name and domain name.

Problem

The root account does not have create access to the org_dir object in the NIS+ domain.

Verification: Enter the command:


niscat -o org_dir

Solution: Use the nischmod command to change the permissions on the table.org_dir.domainname.

I/O Error Accessing File Name Service

The following error message is displayed:


File system I/O error number accessing file datastore.

If you receive this error message, look through the list of error messages below, which are returned by the operating system when it tries to open, read, or write a file in /var/dhcp.

Problem

The error number is 2 (ENOENT).

Verification: The file or directory does not exist.

Solution: Enter the dhcpconfig command to create it.

Problem

The error number is 13 (EACCES).

Verification: A UNIX permission error occurred accessing the file or directory.

Solution: Use the su command and change the UNIX permissions.

User Has no DES Credentials

Problem

The following error message is displayed:


The user user does not have DES credentials in the NIS+ name service.

Verification: The current system's root account does not have valid Data Encryption Standard (DES) credentials in the NIS+ cred table.

Solution: Use the nisaddcred command to add the credentials for the root account. You must enter the UNIX netname and NIS+ principal name on the command line.

The following example shows how to add DES credentials for the system mercury in the domain Faxco.COM. 

nisaddcred -p unix.mercury@Faxco.COM \
-P mercury.Faxco.COM. DES Faxco.COM

The command prompts for the root password (which is required to generate an encrypted secret key).

No Permission to Create Table in Data Store

The following error message is displayed:


You do not have permission to create the tablename table in the servicename data store.

If you have a problem creating tables in the data store, check the information below.

Problem

The root account does not have access rights to create a table under the org_dir object.

Verification: Usually, this means the root account's principal name is not a member of the owning group for the org_dir object, or no owning group exists.

Solution:

  1. Enter niscat -o org_dir to see the name of the owning group.

  2. Enter nisgrpadm -l admin to see the group members.

  3. If the current system's principal name is not in the group, enter nisgrpadm -a group principalname to add it.

  4. Enter /usr/lib/nis/nisctl -f g to flush the cache for immediate update.

Unable to Determine Name Servers

Solutions to problems in finding a name server during configuration of the DHCP server are listed below.

Problem

The dhcpconfig script could not match server names with IP addresses.

Verification: Find the IP address of the server by using the command getent hosts name.

Solution: Create the entries in the hosts database.

Problem

The dhcpconfig script is using the wrong name service for the server.

Verification: Look at the hosts entry in the /etc/nsswitch.conf file to see which name service is used to look up IP addresses (xfn, files, nis, nisplus, dns).

Solution: Change the hosts directive in the /etc/nsswitch.conf file to the correct name service. Stop and restart nscd.

Problem

The dhcpconfig script did not check the name service.

Verification: The name service preceding the [NOTFOUND=RETURN] directive in the /etc/nsswitch.conf file is authoritative. If the specified name service does not find an entry, any name services listed after this directive are not checked.

Solution: Remove the [NOTFOUND=RETURN] directive from the /etc/nsswitch.conf file and run the dhcpconfig script again. Stop and restart nscd.

Errors Trying to Set Up DHCP Table

One of the following error messages is displayed:


The user username does not have permission to update the dhcptab table in the servicename resource.


Error 10 from the Table subsystem accessing dhcptab table, message: NIS+ error while executing nis_modify_entry for [key=SUNW.PCNFS.5.1.1,flag=m],dhcptab.org_dir.island.ocean.: Permission denied Error trying to set up DHCP table, exiting.


Error 10 from the Table subsystem accessing dhcptab table, message: NIS+ error while executing nis_modify_entry for [key=SUNW.PCNFS.5.1.1,flag=m],dhcptab.org_dir.island.ocean.: Object with same name exists Error trying to set up DHCP table, exiting.

If you receive one of these error messages, check the information below for solutions to problems trying to set up DHCP tables during the configuration of the DHCP server.

Problem

You do not have access rights to add entries into DHCP tables from NIS+ or the UNIX file system.

Verification: Check permissions and set appropriate access rights for the DHCP table.

Solution: Make sure the administrator is a member of the appropriate administrative group and has write access to the NIS+ master server.

No Permission to Access dhcp_network Table

The following error message is displayed:


You do not have permission to create {update} the tablename table in the servicename data store.

If you receive this message, check the information below regarding a problem. Listed below are solutions to problems accessing the dhcp_network table during the configuration of the DHCP server.

Problem

You do not have access rights to add entries into the dhcp_network table from NIS+ or the UNIX file system.

Verification: Check permissions and set appropriate access rights for the dhcp_network table.

Solution: Make sure the administrator is a member of the appropriate administrative group and has write access to the NIS+ master server.

Troubleshooting a DHCP Client

When troubleshooting a DHCP client, you must understand certain issues about configuring the client and client-server communication. DHCP may fail to configure the client properly, either because DHCP could not communicate with a server, or because, although configuration responses were received, they were incorrect. Problems can also occur later in the life of a DHCP lease if the client cannot renew its IP addresses.

Client Cannot Communicate With the Server

When a client and a server cannot communicate with each other, the consequences depend on whether or not the client has a configuration cached from an earlier DHCP transaction. If it has, and if the lease is still valid, the client will use the cached data to configure the interface.

However, because the client has received no outside confirmation that this configuration is valid, there is no guarantee that the IP address, router address, and other information are valid. If the interface is connected to a network other than the one on which the configuration was received, one of two things can happen. Either errors may appear when other network services are started, or it may be impossible to communicate with other hosts on the network.

On the other hand, if no cache with an unexpired lease exists, the interface is not configured.

DHCP Configurations Received Are Invalid

Configurations can be invalid for two reasons:

  1. The client determines by ARP that the IP address offered to it is in use elsewhere. In this case, the client will send a DHCPDECLINE message to the server. If the server offers more than two bad addresses, dhcpagent fails.

  2. The client gets offers, but when it tries to confirm them, the server sends a DHCPNAK message instead of a confirmation. If the client receives DHCPNAK messages more than twice, dhcpagent fails. This indicates a malfunctioning server.

Isolate the Problem to the Client or Server

Perform the following actions to isolate the problem to either the client or the server machine.

Problem

The DHCP server machine is not working.

Verification: Log in to another machine on the same subnet as the client, and use the ping command to try to reach the server.

Solution: Diagnose the problem on the server machine.

Problem

The DHCP server is not running.

Verification: Log in to the server and enter the command:


ps -ef | grep dhcp

Solution:

  1. Stop and restart the DHCP server.

  2. Enter the command:


    /etc/init.d/dhcp stop

  3. Wait about 10 seconds. Then enter the command:


    /etc/init.d/dhcp start

Problem

The boot process hangs during DHCP.

Verification: The interface is marked primary, but no valid DHCP transaction has occurred.

Solution: Interrupt DHCP by typing control-C. The boot continues.

Note -

Although booting continues, the host may be incorrectly configured for the networks to which it is attached.

Client Cannot Reach DHCP Server

Problem

After configuring the DHCP client software and rebooting the client, you are unable to reach a server on the network from the client. All DHCP network commands fail and you see messages that the client is trying to reach the DHCP server and failing.

Typical error messages include:


DHCP or BOOTP server not responding


A request to access nonexistent dhcp_network database: databasename in datastore: datastore.


No more IP addresses for network_address network.

Verification: To pinpoint exactly what the problem is, perform the following actions.

  1. Run the client in debug mode.

  2. Attempt to configure the interface manually to verify that the hardware is functioning.

  3. Run the DHCP server in debug mode.

  4. Use snoop to trace messages sent between the DHCP server and client.

  5. Find out if the problem is on the client or server machines.

  6. Look at the error message and choose a solution from the information below.

Run Client in Debug Mode

Run the client in debug mode. Refer to the documentation for the product you are running.

Solaris 2 Client:

  1. Invoke:


    /sbin/dhcpagent -d3

DOS Client

On a PC-NFS DOS client:

  1. Edit the AUTOEXEC.BAT file by replacing SNCLIENT with SNCLIENT /D.

  2. Reboot the client.

Configure the Interface Manually

After dhcpagent has been started in debug mode, you can try to configure an interface manually by typing:


ifconfig interface_name auto_dhcp

Packets that are sent, and any that are received, will be displayed.

Run the Server in Debug Mode

  1. Log in to the root account on a DHCP server on the same subnet as the client.

  2. Kill and restart the DHCP server in debug mode. For example: 


    /etc/init.d/dhcp stop
/usr/lib/inet/in.dhcpd -d -v
    Or, if the i option is present, enter the command in the following format:

    /usr/lib/inet/in.dhcpd -i interface_names -d -v

Use snoop to Monitor Network Traffic

  1. Log in to the root account on a DHCP server or BOOTP relay agent on the same subnet as the client.

  2. Use the snoop command to trace network traffic. For example:


    snoop -o /tmp/output udp port 67 or udp port 68
    or 

    snoop -o /tmp/output udp port bootps or udp port bootpc
    plus the per-interface argument, if there is one.

  3. Boot the client and watch the network messages on the server.

  4. Type: 


    snoop -i /tmp/output -x 0 -v
    to view the packet traces.

Look up Error Messages

Look at the output from running the in.dhcpd command in debug mode and use the error message or condition you see to find a solution from the information below.

Problem

You see one of the following error messages:


Datagram received on network device: le0


ICMP ECHO reply to OFFER candidate: ip_address disabling

Verification: Before the DHCP server offers an IP address to a client, it verifies that the IP address is not in use by pinging the IP address. If a client replies, the IP address is in use.

Solution: Make sure the IP addresses you configured are not already in use.

Problem

You see the following error message:


No more IP addresses for network_address network

Verification: There are no available IP addresses in the client's dhcp_network table.

Solution: Use the dhcpconfig command to allocate more IP addresses. If the DHCP daemon is monitoring multiple subnets, be sure the additional IP addresses are for the subnet where the client is located.

Problem

There is a bad client id: id_name in the dhcp_network database.

Verification: The client ID (MAC address) in the dhcp_network table is incorrect.

Solution: If you are using Ethernet, the client ID is 01 followed by the Ethernet address. Make sure that all letters in this address are capitalized. A 00 means the address has not been assigned.

Problem

You see the following error message:


Request to access nonexistent dhcp_network database: database_name in datastore: nisplus_datastore.

Verification: The dhcpconfig script did not create a dhcp_network table for a subnet during the configuration of the DHCP server. This can happen if you set up an isolated LAN, such as a server and two clients, as a test network.

Solution: Use the dhcpconfig command to initialize the dhcp_network table and new IP addresses.

Problem

You receive the error message:


Client client_id is trying to verify unrecorded address ip_address, ignored.

Verification: There are two possible reasons for getting this message:

  1. You can receive this message if your dhcp_network tables have been deleted. If you are using only the Solaris 2 DHCP server, then this is typically the reason.

  2. You can receive it if you are not using NIS+ for datastore, so information is not shared. Make sure that the server is sharing data.

If you have a group of heterogenous servers, then ignore this message.

Solution: Remove old cache files on the client by typing:


ifconfig interface_name dhcp release

Problem

DHCP is started, but some required network services will not start.

Verification: The DHCP server is not supplying the configurations required.

Solution: Find out why the server does not send the parameters that are required. Configure the server to do so.

Problem

DHCP is started, but certain network services, such as NIS and NIS+, report errors or hang. The host cannot communicate with other hosts on the network.

Verification: The dhcpagent command was unable to communicate with DHCP (presumably because DHCP was unavailable) and has used cached data.

Solution: Remove the cache. Type:


ifconfig interface_name dhcp release

Since removing the cache does not solve the problem of getting the proper configuration, the host may have to be configured by hand. At boot time, DHCP should be disabled by removing the trigger file by typing:


rm /etc/dhcp.interface_name

Problem

The client boots and works correctly, but the following message appears:


DHCP renewal on interface_name failed

Verification: DHCP is working, but dhcpagent cannot contact the server to extend the lease.

Solution: Find out why the server is not responding now. This could be because the router value configured in the dhcptab is incorrect or out of date for the client network.

Problem

Messages about failed DHCP renewals are received. Then the following message appears on the console:


DHCP lease expired on interface_name: interface is now down

Network services may hang at this point.

Verification: The lease has expired. The client has not been able to extend the lease after several attempts.

Solution: Find out why the server is not responding. Reboot the client.

Some Clients Do Not Boot From DHCP Server in BOOTP Compatability Mode

Problem

The DHCP daemon is running in BOOTP compatibility mode (-b option).

Verification: BOOTP does not use a lease time. The DHCP server looks for free addresses with the BOOTP flag set to allocate the BOOTP clients.

Solution: Allocate BOOTP addresses. Use dhcpconfig to change the daemon options.

Diagnose NIS+ Configuration Problems

Use the information below to fix errors in the configuration of the NIS+ name service that prevent the client from accessing a server during boot.

Problem

No name service is configured for the client in the dhcptab table.

Verification: Log in to the server and type the command:


dhtadm -P | grep ip_address

Check for entries such as NISdmain, DNSdmain, and NISservs. Make sure the addresses entered for them are correct. For example:


# dhtadm -P | grep 129.148.3.129.148.3.m:Subnet=255.255.255.0:Router=129.148.3.11: 
Broadcast=129.148.3.255:NISdmain="island.ocean":NISservs=129.148.3.3:

Note -

The line above actually appears on one line, instead of being broken into two.

Solution: Use dhtadm to change any incorrect addresses.

Problem

You are using NIS+ and the server is not running in NIS+ compatibility mode. NIS+ tables do not have read rights for the Nobody category, so NIS clients cannot access the information stored there.

Verification: Run the command:


nisls -l org_dir
to show permissions of .r---rmcdrmcdr---

Check whether the Y option is set for the rpc.nisd daemon. For example: 


ps -deaf | grep nis

Solution:

  1. Log in to the NIS+ server as root.

  2. Enter the command:


    /usr/lib/nis/nisserver -r -Y -d domainname

Problem

An incorrect default router prevents the client from reaching a server on another network.

Verification: Make sure the router symbol definition in the dhcptab table is actually a router.

Solution: Use dhtadm to correct the route symbol in the table.

Problem

You are running NIS+ but DNS forwarding is not turned on for NIS clients.

Verification: Use the command:


ps -ef | grep rpc.nisd

A -B option means that NIS is running with DNS forwarding turned on. For example: 


/usr/sbin/rpc.nisd -B

Solution: Start the NIS+ server in NIS compatibility mode with DNS forwarding enabled. For example:


/usr/sbin/rpc.nisd -YB

Diagnose Name Service Configuration Problems

Use the information below to fix errors in the configuration of the NIS name services that prevent the client from accessing a server during boot.

Problem

An incorrect default router prevents the client from reaching a server on another network.

Verification: Make sure the router symbol definition in the dhcptab table is actually a router. If there are problems with the default router, make corrections with server-based tools.

Solution: Use dhtadm to correct the route symbol in the table.

Problem

No name service is configured for the client in the dhcptab table. For clients, the name service must be DNS, NIS, or NIS+, and appropriate parameters must be provided to each client.

Verification: Check the network-specific macro relating to the client's configuration.

  1. Log in to the server and type the command:


    dhtadm -P

  2. Look for an entry that matches your client's network.

    Solution: Use dhtadm to correct the client's macro for the name service:

    If this is the first client on the network:

  1. Use dhtadm to correct the entries.

  2. Then type:


    /etc/init.d/dhcp stop, 
/etc/rc3.d/S34dhcp start
    on the server and reboot the client.

    Note -

    The server does not dictate the name service choice to the client. The server only provides the relevant information. The client chooses its name service.

Macro Change Not Propagated to Client

You have changed one or more macros for a client with dhtadm, but the changes are not evident on your machine. For example, you changed the client's router, but the client is still using the old router.

Use the information below to solve the problem of changed client macros not showing up on the DHCP server.

Problem

The DHCP server was not reinitialized to read your changes to the dhcptab table. This must be done every time you change a macro definition.

Solution: Use the rescan option-set with dhcpconfig, or:

Reinitialize the DHCP server:

  1. Log in to the DHCP server as root.

  2. Enter:


    /etc/init.d/dhcp stop

  3. Restart the DHCP daemon by entering:


    /etc/init.d/dhcp start