How to DHCP with Open DHCP Server - Quick Walkthrough

A quick install, setup, and run of Open DHCP Server.

1) Obtain Open DHCP Server from:

https://sourceforge.net/projects/dhcpserver/

2) Double-click the OpenDHCPServerInstallerVX.XX.exe

And follow the prompts to install.

Image: Open DHCP Server Installer

Image: Open DHCP Server Installation

The install runs -

C:\OpenDHCPServer\installservice.exe

- which installs a service ‘OpenDHCPServer’ with the path to executable:

C:\OpenDHCPServer\OpenDHCPServer.exe

Image: Installing OpenDHCPServer - Installation Completed

Image: Open DHCP Server Service

Image: Contents of Install Folder C:\OpenDHCPServer

3) Edit OpenDHCPServer.ini as required

Note: Save the original .ini as say .ini.backup

4) To run, double-click ‘RunStandAlone.bat’.

5) To stop, close the cmd.exe window.

IMPORTANT NOTE: Before running OpenDHCP, be very careful that OpenDHCP is not connected/listening on any networks that it shouldn’t be. You don’t want to accidentally give out DHCP addresses.

Note: The ‘Open DHCP Server’ service only runs if you need to run Open DHCP as a service. Default state is ‘Startup Type’ = ‘Automatic’ and ‘Status’ = ‘Not Running’. When you run ‘RunStandAlone.bat’ that doesn’t start the service.

Image: Running OpenDHCP

Configuring IPMIs using OpenDHCP (or Not Having to Plug a KVM into every Server to Configure the IPMI/iLO/DRAC/whatever)

The reason why I’m writing a post about Open DHCP Server, is because I sometimes have to configure a number of servers (e.g. NetApp HCI/NetApp SolidFire) and it’s a bit of a pain needing to go to every server with a Keyboard, Video, Mouse (KVM), and configure the IPMI by: boot node, wait for key press to enter setup, configure IPMI, reboot, and so on (if there is already DHCP on the IPMI network, it can help.)

Using OpenDHCP and a portable switch (I bought a Netgear ProSafe GS116 for about £60), I can plug up to all the IPMI ports, see what’s got what on my private DHCP scope, connect over IPMI, and apply whatever configurations are required, without needing KVM (also, can RTFI nodes over the IPMI with new images if required, rather than carrying a set of USB keys.)

I set just:

[LISTEN ON]

{IP of my laptop on the IPMI network}

[RANGE_SET]

DHCPRANGE = {Range of IPs I want to use - i.e. not the static IPMI IPs I will configure later}

SubNetMask={as required}

Router={as required}

Image: Very simple OpenDHCPServer.ini example

The default HTTP interface for OpenDHCP is http://127.0.0.1:6789/ and for some reason this didn’t work for my laptop. Not a massive issue as can see all the DHCPREQUEST in the cmd.exe. The error was “HTTP Client 127.0.0.1, Message Receive failed, WSAError 0”. I tried on another laptop, didn’t get that error, but still the webpage failed to load.

Image: Netgear ProSafe GS116 16-port Gigabit Switch