HP-UX IP Address and Client Management Administrator's Guide HP-UX 11i v2, HP-UX 11i v3
Monitoring and Troubleshooting DHCP Operations
This section describes techniques and tools that you can use to troubleshoot problems encountered
with the DHCP server.
Troubleshooting Techniques
You can use one of the following techniques for monitoring DHCP:
• Syslog with debugging turned on
• Trace DHCP packets flowing in and out
• Dump the internal state of the daemon
• Review the contents of the /etc/dhcpdb file
Using Syslog with Debugging Turned On
The /var/adm/syslog/syslog.log file contains a detailed real-time information of all the
operations. However, this method is only good for monitoring operations over short periods of
time because the /var/adm/syslog/syslog.log file grows quickly.
To enable the debugging option perform the following steps:
1. Open the /etc/inetd.conf file in an editor.
2. Insert the -d3 option in the bootp entry in the /etc/inetd.conf file.
bootps dgram udp
wait root /usr/lbin/bootpd bootpd -d3
3. Reconfigure inetd using the following command:
# inetd -c.
You must restart bootpd to use the debugging command-line option d3. Terminate bootpd.
4. Tail the syslog file by executing the following command:
tail -f /var/adm/syslog/syslog.log grep bootp
Perform the following checks on the output:
• Is the client request reaching the server?
• Does the server make a reply to the client?
• Is the reply appropriate for the client?
Table 4-1 lists some of the common error messages you may see in the syslog file when a client
fails to get an address lease.
Table 4-1 Common Errors Found in Syslog
CauseError
A client requests an address on a subnet not available or accessible from this DHCP server. The
client gets no response from this server.
304
The pool or device group is full, that is the DHCP server has assigned all the addresses available.
The client gets no response from this server.
305
An illegal packet received.308
The DHCP server does not know anything about the client lease or has forgotten about the
lease. In this case, the client falls back to request a new lease.
316
Tracing DHCP Packet Flow
You can turn on tracing by executing the following command:
/usr/sbin/dhcptools -t ct=100
This command writes all contents of 100 packets to a file called /tmp/dhcptrace.
124 Configuring DHCP