DHCP, Task: Monitor and resolve alerts indicating DHCP conflict (rogue detection and IP in use)

Task: Monitor and resolve alerts indicating DHCP conflict (rogue detection and IP in use)

Purpose

Detect and protect against unauthorized and illegal DHCP servers.

Procedure 1: Detect and identify DHCP servers that are not part of a known list

To detect rogue DHCP servers on a local subnet

1. On a client or server other than the DHCP server, open a command shell by clicking Start, then Run, typing cmd and clicking OK.
2. Enter the Dhcploc.exe utility command:
   dhcploc -p -a:"dhcpadmin” -i:360 16.23.23.4 “23.1.2.44 23.1.2.45”
   This will run the Dhcploc utility on the local interface having the IP 16.23.23.4. The tool will send a discovery packet, and DHCP servers that respond but do not have the IP address of 23.1.2.44 or 23.1.2.45 will trigger an alarm to Dhcpadmin user every three minutes (-i:360).
3. When Dhcploc is running, type d to discover.

Dependencies

    None

Technology Required

• Dhcploc from the Windows Server 2003 \Support\Tools directory on the Windows Server 2003 Install CD
• Base DHCP Windows Server 2003