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How to configure standalone Open DHCP Server application?

Open DHCP server is free software used to provide IP addresses on your client network.  The latest version can be downloaded from http://dhcpserver.sourceforge.net/

Software installation is very simple, it is done through downloaded installer with a few clicks.

You should let installer install server as NT Service.
Server configuration is done through OpenDHCPServer.ini file which is located in the Open DHCP installation folder.

To configure the Open DHCP server, please follow these steps:

(If using Windows ICS) Change the IP address of your network card (192.168.0.1) to some other IP e.g. 192.168.100.1

Open Windows Start menu and go to Programs – Open DHCP Server – Configure entry

Important: All configuration entries that have ‘ character in front of them will not be used

• Go to [LISTEN_ON] section and replace default IP address with the address of your network card connected to the client network.
• Go to the first [RANGE_SET] section.
• Set DHCP_Range value, this option determines which IP addresses will be leased to client computers, e.g. 192.168.100.2 – 192.168.101.254.
• Set Subnet_Mask that will be assigned to clients, it must match DHCP_Range, for the example above it would be 255.255.254.0
• Specify primary and secondary DNS_Server which your clients will use to resolve web addresses (it could be DNS server of your ISP or some free like Google DNS 8.8.8.8, 8.8.4.4.)
• Router value will be used to set gateway address on client computers, this value has to match the IP address of server network card connected to the client network.

After you configure DHCP server settings, you need to start Open DHCP server service from Control Panel – Administrative Tools – Services application or restart server pc to automatically run DHCP server.

If the program is not assigning addresses, please check:

1. Check network hardware and ensure that client machines have different hostnames from the server and each other.

2. No other service should be running on Server on ports 67.

3. If you get an error like port 67 already in use means some other DHCP program or proxy server with DHCP service is running. Use any port scanner program like Active Ports to detect which program is listening on these ports. It is also possible that another copy of DHCP server itself is running, or Microsoft connection sharing (ICS) is running, which uses these ports.
How to disable ICS DNS/DHCP Service on your target networks, see above INTERNET CONNECTION SHARING.

4. If you still get error Static Interfaces/Listening Ports not available, it may be because of another DHCP Server is running or Interfaces specified on [LISTEN-ON] section are not available. If your interface may not be ready when your computer/Service starts and due to this service fails to start, use Window’s recovery option in Services applet to try starting service at the later time.

5. Look at OpenDHCPServer.log (if running as service) or Run in standalone mode, it will provide all debug information as it verbatim the activities.

6. If you use Broadband router, which also has DHCP Server, this program may still run, but some hosts configured by other DHCP Server may not use this DNS or DHCP Service.  Please disable DHCP Service on Broadband Router.

7. DHCP server state file backs up current leases and is read back when the server restarts. If you want to clean previous leases, you may delete this file and restart the server.

8. If you are not able to receive DHCP Discover messages from clients, make sure that DHCP server and client are on the same physical network (not separated by routers).
If it is separated by routers and it is the same subnet, please allow routers to pass broadcast messages to Server on Port 67. If these are different subnets, use the BOOTP relay agent.

Updated on November 12, 2020

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