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Barracuda CloudGen Firewall

This Firmware Version Is End-Of-Support

Documentation for this product is no longer updated. Please see https://campus.barracuda.com/doc/71862301/ for further information on our EoS policy.

How to Configure the DHCP Service

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Configure the DHCP service 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. 

In this article:

Before you Begin

You must have a Virtual Server IP for each subnet you want to use for the DHCP server. For more information, see Virtual Servers and Services.

Configure the DHCP Service

  1. Open the DHCP Enterprise Configuration page (Config > Full Config > Box > Virtual Servers > your virtual server > Assigned Services > DHCP-Service).
  2. Click Lock.
  3. In the left menu, select Operational Setup IPv4 or 6.
  4. In the Address Pool Configuration window, enable DHCP.
  5. Click + to add an entry to the Subnets table.
  6. Enter a descriptive name for the subnet and click OK. The Subnets configuration window opens.
  7. From the Used Subnet list, select one of the available IPv4 subnets or select explicit and enter the IP address in the Network Address field.

    When using IPv6 select any (stateless dhcp) to use DHCPv6 to extend IPv6 with DHCP capabilities (assigning domain name or DNS servers).

  8. In the DHCP Server Identifier field, enter the name of the server. This name is provided to the client.
  9. Click + to add a new entry to the Pool Ranges table.
  10. Specify the following for each range:
    • IP Begin – The first IP address in the network range. E.g.:
    • IP End – The last IP address in the network range. E.g.:
  11. Click OK.
  12. (optional) Add MAC to IP address mappings to the Reservations table:
    1. Enter the Reserved IP which the client gets assigned. Reserved IP addresses must reside outside of the DHCP pool range.
    2. Enter the MAC Address to identify the client.

  13. Click OK.
  14. In the Router table, add the default gateway IP address. E.g.:
  15. In the DNS Servers table, add the DNS server IP address. E.g.:
  16. Enter the Domain Name if the client range is part of a domain.
  17. Enter the NIS Domain Name and specify the details required for all servers that should be assigned.
  18. In the Static Route Net table, click + to add static routes that the client should install in its routing cache. If there are multiple routes to the same destination, list them in descending order of priority.
    1. In the Static Route Net field, enter the destination IP address.
    2. In the Static Route GW field, enter the IP address of the router.
    3. Click OK.
  19. Enter the TFTP Server Name if the 'sname' field in the DHCP header has been used for DHCP options.
  20. Enter the TFTP Server IP Address for Cisco CallManager devices. In this field, you can enter a comma-delimited list of addresses.
  21. Enter the Boot File Name if the 'file' field in the DHCP header has been used for DHCP options.
  22. If you set the Barracuda Network Access Clients Policy of an Address Pool to Barracuda Network Access Clients or guests, add the required info to the Access Control Service IPs/Names table for a client to receive valid policy server information.

    You can add vendor IDs, policy server IP addresses, or DNS resolvable policy server names. If the Barracuda Network Access Clients Policy field is set to none, the information in the Access Control Service IPs/Names table is ignored.

  23. For information on dynamic DNS configuration, refer to How to Configure DHCP with Dynamic DNS.
  24. For information on lease configuration, refer to How to Configure DHCP Parameter Templates.
  25. Click OK.
  26. Click Send Changes and Activate.

Check the DHCP Server Status

Click the DHCP Tab to check the real-time status of the configured DHCP server. 

Configure Advanced DHCP Settings

  1. Open the DHCP Enterprise Configuration page for the DHCP service (Config > Full Config > Box > Virtual Servers > your virtual server > Assigned Services > DHCP-Service).
  2. From the left Configuration Mode menu, select Switch to Advanced View.
  3. Click Lock.
  4. In the left pane, select Operational Setup IPv4 or 6.
  5. In the Address Pool Configuration window, enable DHCP.
  6. Enable Use Advanced Pool Configuration. This disables the Subnets section and allows configuration of address pools.
  7. In the DHCP Server Identifier field, enter the name of the server. This name is provided to the client.
  8. Enable Server Is Authoritative.

    When the DHCP server receives a DHCPREQUEST message from a DHCP client requesting a specific IP address, the DHCP protocol requires that the server determines whether the IP address is valid for the network to which the client is attached. If the address is not valid, the DHCP server should respond with a DHCPNAK message, forcing the client to acquire a new IP address. To make this determination for IP addresses on a particular network segment, the DHCP server must have complete configuration information for that network segment. Unfortunately, it is not safe to assume that DHCP servers are configured with complete information. Therefore, the DHCP server normally assumes that it does not have complete information and, thus, is not sufficiently authoritative to safely send DHCPNAK messages as required by the protocol.

  9. Select the UDP Listen Port on which the DHCP server listens for DHCP requests. By default, the server listens on port 67.

  10. For an HA setup, edit the settings in the HA Synchronisation Setup section to synchronize the DHCP database between both units:

    1. Enable HA Synchronisation to synchronize the DHCP database between the HA units.

    2. Specify the HA synchronization interval if required (default: 300 seconds).

  11. Click Send Changes and Activate.
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