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Barracuda CloudGen Firewall

How to Configure Layer 2 Bridging

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When performing layer 2 bridging, the Barracuda CloudGen Firewall will be completely transparent to the user. The interface is not assigned an IP address and cannot be directly contacted by the user in the bridged networks. Traffic passing through the layer 2 bridge will retain its original MAC address with the bridge acting as a proxy ARP in the middle. Since the bridged network interface does not have an IP address, you will need to use a separate interface to locally administer the Barracuda CloudGen Firewall. You can define multiple bridging groups on one interface. Traffic between the interface groups is forwarded on layer 3. Define a pass and a broad-multicast access rule for each bridge interface group.

The bridge can only be used for IP-based protocols.

fw_layer2_bridge.png

Step 1. Configure Transparent Layer 2 Bridging

  1. Go to CONFIGURATION > Configuration Tree > Box >Virtual Servers > your virtual server > Assigned Services > Firewall > Firewall Forwarding Settings.
  2. In the left menu, select Layer 2 Bridging.
  3. Click Lock.

  4. In the Bridged Interface Group table, click + to add an entry. For each interface group, you can edit the following settings:

    • Bridged Interfaces – Add all interfaces to be bridged together in this group. For each interface enter the following settings:
      • Name – The exact network interface label, as listed in the network configuration. E.g., eth1
      • Allowed Networks (ACL) – Networks that are allowed to communicate over the bridged interface. You can enter complete networks, individual client/server IP addresses, or network ranges.
      • Unrestricted MACs – List of MAC address for which the Allowed Networks (ACL) does not apply.
      • MAC Change Policy – Select Allow–MAC–Change to permit the MAC address of the interface to be changed; otherwise, select Deny-MAC-Change.
    • Use IP BARP Entries –  Select yes if the Barracuda CloudGen Firewall must learn the MAC addresses from IP and ARP traffic and record IP addresses that are assigned to a specific MAC address in a separate table. If there are a very large number of IP addresses in a specific network segment, select no to keep the ARP table from being overrun

    trans_l2_config.png

  5. Click OK.
  6. Click Send Changes and Activate.

Step 2. Create Access Rules for Layer 2 Bridging

To allow network traffic to pass between the bridged interfaces, create Pass and Broad-Multicast access rules for every bridged interface group.

  1.  Go to CONFIGURATION > Configuration Tree > Box > Virtual Servers > your virtual server > Assigned Services > Firewall > Forwarding Rules.

  1. Click Lock. 
  2. Create a pass access rule with the following settings:
    • Action – Select PASS
    • Bi–Directional – Yes
    • Source – Select Any (0.0.0.0/0)
    • Service – Select Any
    • Destination – Select a network object containing all networks or IP addresses for the bridged interfaces. E.g., 10.0.8.0/24 and 172.31.1.25
    • Connection Method – Select Original Source IP
  3. Create a Broad–Multicast access rule with the following settings:
    • Action – Select Broad-Multicast.
    • Source – Select a network object containing all networks or IP addresses for the bridged interfaces. E.g., 10.0.8.0/24 and 172.31.1.25
    • Service Select Any
    • Connection Method – Select Original Source IP
    • Destination – Enter the destination networks/IP addresses. E.g., 10.0.8.25

      To use a DHCP server over the layer 2 bridge, also add 0.0.0.0 to the source and 255.255.255.255 to the destination IP addresses.

    • Propagation ListEnter the propagation interface or IP address(es). For more information, see How to Create a Broad-Multicast Access Rule.
  4. Rearrange the order of the access rules so the new rules can match incoming traffic.
  5. Click Send Changes and Activate.

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