The Book

DHCP test client
Another great tool to use is the DHCP test client. This sniffs the network until a DHCP Offer / DHCP Ack is detected on UDP port 68 and shows the received information.

The benefit of the DHCP test client is that you don’t have to install anything, just run the tool and initiate a DHCP request.

32 bit DHCP test client & 64 bit DHCP client can be downloaded from:

http://files.thecybershadow.net/dhcptest/

Since the DhcpInterfaceOptions is always accessible (even when the client already received the DHCP offer) I wanted to have the ability to read the content. So I wrote a PowerShell script that reads the registry key for each DHCP enabled NIC and shows the received DHCP options.

The script shows all Dhcp options and vendor specific Dhcp options (43).

ReadDhcpOptions

You can find the PowerShell script here: ReadDhcpOptions

The archive contains three files

  DhcpOptions.csv – Semicolon separated file containing all Dhcp Options (IANA) and their data type;
  DhcpOptionsVS.csv – Semicolon separated file containing some vendor specific Dhcp Options;
  ReadDhcpOptions.ps1 – The actual PowerShell script
  

DHCP Options list:

http://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml

PowerShell script can be downloaded from:

http://www.ingmarverheij.com/download/5839/

Before executing PS Script, script execution has to be enabled in PS:

Get-ExecutionPolicy
Set-ExecutionPolicy RemoteSigned