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7 troubleshooting dhcp problems – HP Insight Control Software for Linux User Manual

Page 229

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25.7 Troubleshooting DHCP problems

The following table describes possible causes of problems with Dynamic Host Configuration
Protocol (

DHCP

) and provides actions to correct them.

Corrective actions

Cause/Symptom

Perform the appropriate action:

Verify that the /etc/dhcpd.conf service
configuration file exists and that it is not empty.

Verify that the /etc/dhcpd.conf service
configuration file is valid. Verify it against the output
of the examples in dhcpd.conf(5).

Verify that DHCP is configured to serve IP addresses
on the correct network interface. Compare the output
of the ifconfig command and the contents of the
/etc/sysconfig/dhcpd

file to identify the correct

interface.

Start the DHCP service with the following command:

# /etc/init.d/dhcpd start

Examine the /var/log/messages system log file for
error messages, and take any corrective action
required.

DHCP Process Not Running

The DHCP server process is absent from the process list,
verified with the following command:

# ps –ef | grep dhcp

Perform the appropriate action:

Verify that the /etc/dhcpd.conf service
configuration file is valid. Verify it against the output
of the examples in dhcpd.conf(5).

Verify that DHCP is configured to serve IP addresses
on the correct network interface. Compare the output
of the ifconfig command and the contents of the
/etc/sysconfig/dhcpd

file to identify the correct

interface.

Examine the /var/log/messages system log file for
error messages, and take any corrective action
required.

DHCP Process Will Not Start

Any attempt to start the DHCP process fails with errors.

Verify that DHCP is configured to serve IP addresses
on the correct network interface. Compare the output
of the ifconfig command and the contents of the
/etc/sysconfig/dhcpd

file to identify the correct

interface.

Verify that the IPTables on the CMS does not block
DHCP requests. Either examine the IPTables rules to
ensure that the UDP ports 67 and 68 are allowed, or
turn the firewall off.

Verify the /etc/dhcpd.conf file to verify that DHCP
is configured with sufficient IP addresses to supply
addresses for each of the managed systems, their
management processors, and onboard administrators.

Examine the /var/log/messages system log file for
error messages, and take any corrective action
required.

DHCP Process Runs But Does Not Provide IP Addresses

The DHCP process appears to run, verified with the
following command, but the clients on the network are
not receiving IP addresses.

# ps -ef | grep dhcp

25.7 Troubleshooting DHCP problems

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