How to Block Multicast Traffic in a VWire (Virtual Wire) Setup

How to Block Multicast Traffic in a VWire (Virtual Wire) Setup

Created On 09/25/18 17:59 PM - Last Modified 02/07/19 23:53 PM


Multicast traffic is blocked in the Layer-3 mode by default, but is forwarded by default in the Virtual Wire mode.

To apply security policies for multicast:

  • Enable multicast firewalling under the Virtual Wire configuration:

    8-16-2012 9-24-59 AM.png

Multicast traffic transiting through the firewall can now be blocked, by either blocking the entire global multicast IP address range, or by blocking PIM and IGMP under the security rule.

Note: Before blocking multicast, consider routing protocols that use multicast (OSPF, RIP, VRRP for example). If they are in use on the network, they will be blocked as well.

  • Blocking the entire Multicast address range

    8-16-2012 9-27-44 AM.png

  • Blocking the protocol PIM and IGMP, using application signatures

    8-16-2012 9-28-50 AM.png

  • This is how the rule would look to block multicast on Virtual Wire (click to enlarge):

    8-16-2012 10-46-48 AM.png

owner: kprakash

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