About forwarding broadcasts destined for the directly connected network
A directed broadcast packet is destined for all hosts on a specific network. In the destination IP address of the directed broadcast, the network ID identifies the target network, and the host ID is made up of all ones.
If an interface is allowed to forward directed broadcasts destined for the directly connected network, hackers can exploit this vulnerability to attack the target network. In some scenarios, however, an interface must send such directed broadcast packets to support the following features:
UDP helper—Converts the directed broadcasts to unicasts and forwards them to a specific server.
Wake on LAN—Sends the directed broadcasts to wake up the hosts on the target network.
You can configure this function to enable the interface to forward directed broadcast packets that are destined for directly connected network.