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Barracuda NextGen Firewall X

This Product is End-of-Life and End-Of-Support

End-Of-Life and End-Of-Support on December 1st, 2020: All Barracuda Firewall X-Series sales will cease; neither new sales nor any renewals will be available. If you currently hold a maintenance and support contract, you will continue to receive our award-winning support and services until your contract expires. Please see the End-Of-Life definition as described in the End of Support and End of Life Information.

How to Configure a DHCP Connection

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If the IP address is dynamically assigned by your ISP, follow the instructions in this article to configure the interface.

Before you begin

If your ISP provides a modem, connect the Ethernet port of the modem to a free network interface on the back of your Barracuda X-Series Firewall. Use the Ethernet cable that is delivered with the modem. If a cable was not delivered with the modem, determine if the modem must be connected to another device with a standard Ethernet cable or a crossover cable.

Configure the WAN interface

  1. Go to the NETWORK > IP Configuration page.
  2. In the Dynamic Interface Configuration section, click Add Dynamic Network Interface.
  3. Enter a name for the new connection.
  4. Set Network Protocol to DHCP.
  5. From the Network Interface list, select the network interface that the ISP modem is connected to on the firewall.
  6. Set Classification to WAN.
  7. Configure the remaining settings for your network requirements.
    • In the MTU field, enter the MTU size. If the MTU size is too large, network packets passing the ISP line are fragmented and might decrease the performance of your network performance. For the correct MTU size, contact your ISP.
    • To automatically introduce a network route for this Internet connection, set Create Default Route to Yes.
    • For the initial configuration, keep the default Metric value of 100. In a multiprovider configuration, the firewall chooses the interface with the lowest metric for outgoing traffic.
    • To use the DNS server that is assigned by your ISP, set Use Assigned DNS to Yes. The firewall then uses the DNS servers of the ISP for DNS requests.
    • To make the firewall reachable with a unique identifier (DNS-resolvable name), set Use Dynamic DNS to Yes and enter your DynDNS credentials.

      For more information about the DynDNS service, visit

    • Specify the Connection Timeout for this link. The connection timeout specifies the time in seconds that the firewall waits for an IP address to be assigned. If the defined limit is exceeded, the link is marked as unreachable.
    • To start the link automatically, set Connection Start Method to Automatic.
    • To manually start and stop the linkset Connection Start Method to Manual. To control the link, go to the Dynamic Network Interfaces section of the NETWORK > Interfaces page.
    • To add IP addresses to monitor the Internet connection beyond the gateway, add a target IP address to the Health Check Target list.    
  8. Click Add.
  9. At the top of the page, click on the warning message to execute the new network configuration.
  10. After committing your changes, log back into the X-Series Firewall.