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Barracuda CloudGen Firewall

How to Configure the DHCP Service

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The DHCP server of the CloudGen Firewall automatically assigns IP addresses to clients that reside in a defined subnet. Configure DHCP and specify a network range from which the IP address for the clients will be assigned. In the advanced settings for DHCP, you can configure additional service availability settings, and set up HA synchronization.

Before You Begin

Configure a static interface by using the network the DHCP server subnet is in. For more information, see How to Configure Static Network Interfaces.

Step 1. Enable the DHCP Server

  1. Go to NETWORK > DHCP Server.
  2. In the DHCP Server section, select Yes to enable the DHCP server.
  3. Click Save.

To use the DHCP server within the management network, go to NETWORK > IP Configuration and add a secondary IP address in the Management IP Configuration section.

Step 2. Configure the DHCP Server Subnet

This example configures a DHCP server subnet named LAN that uses an IP range from to, a subnet mask of, and an NTP server at ntp.barracudacentral.com.

  1. Go to NETWORK > DHCP Server.
  2. Click Add DHCP Server Subnet. The Add DHCP Server Subnet window opens.
  3. Enter the DHCP server subnet settings:
    • Name – Enter the name of the DHCP server subnet.
    • Beginning IP Address – Enter the first IP address in the DHCP server subnet. E.g.,
    • Ending IP Address – Enter the last IP address in the  DHCP server subnet. E.g.,
    • Subnet Mask – Enter the subnet mask. E.g.,
    • Gateway – Enter the gateway IP address. E.g.,
    • DNS Server 1 to 4 Enter the IP address(es) of your DNS server(s). 
    • NTP Server 1 to 2 – Enter ntp.barracudacentral.com
    • (optional) Vendor Options – Enter any string containing DHCP options required by your DHCP clients. Make sure to use the exact formatting and delimiters required by your DHCP clients.

  4. (optional) Specify the Default Lease Time and Maximum Lease Time.
  5. If you use WINS servers in your network, enter their IP addresses in the WINS Server 1 and WINS Server 2 fields.
  6. Click Save.

Step 3. Configure the Client

The DHCP server is now ready to assign DHCP leases to connected clients. For clients that currently have manually assigned IP addresses, reconfigure them to receive IP addresses from the DHCP server.

Assigning Static IP Addresses via DHCP

For a client to always receive the same IP address, configure a static DHCP lease. The DHCP server uses the MAC address to identify the client. For more information, see How to Configure DHCP IP Address Reservations.

Removing a DHCP Lease

To free up an IP address that is in use for another DHCP lease, you can delete DHCP leases for inactive DHCP clients. Power off or disconnect the client for the DHCP lease to change its state from active to inactive.

You must force the client to renew the DHCP lease after removing the DHCP lease on the firewall; otherwise, it will continue using the original lease until the maximum lease time expires. This may result in duplicate IP errors in your network!

  1. In the DHCP Server Subnets section, click the trashcan icon in the Actions column. The Clear dynamic lease window opens.
  2. Verify that the IP address matches the DHCP lease you want to delete, and click Clear.
  3. Force the client using this DHCP lease to renew the DHCP lease.

Monitoring Active Leases

In the Active Leases section of the NETWORK > DHCP Server page, you can monitor active DHCP leases. The information for each lease is displayed in the following columns:


Column Description
Range The IP range of the subnet.
Hostname The hostname of the Windows client.
IP Address The percentage of actively used IP addresses from the range.
State The current state of the lease pool and the number of addresses that are in use.
Start The start lease time of the IP address range.
End The end lease time of the IP address range.
MAC Address The MAC address of the client.
Type The type of the IP address. The IP address can be either Static or Dynamic.
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