183
Field Description
INP_ONESBCAST—Sends broadcast packets.
• INP_DROPPED—Protocol dropped flag.
• INP_SOCKREF—Strong socket reference.
• INP_DONTBLOCK—Do not block synchronization of the Internet
PCB.
• N/A—None of the above flags.
TTL TTL value in the Internet PCB.
ip forward-broadcast
Use ip forward-broadcast to enable an interface to receive and forward directed broadcast packets
destined for the directly connected network.
Use undo ip forward-broadcast to disable an interface from receiving and forwarding directed
broadcast packets destined for the directly connected network.
Syntax
ip forward-broadcast
undo ip forward-broadcast
Default
An interface cannot forward or receive directed broadcasts destined for the directly connected
network.
Views
Interface view
Predefined user roles
network-admin
Usage guidelines
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 receive and send such directed broadcast packets to support UDP helper and Wake
on LAN.
This command enables an interface to accept directed broadcast packets that are destined for and
received from the directly connected network to support UDP helper. UDP helper converts the
directed broadcasts to unicasts and forwards them to a specific server.
The command also enables the interface to forward directed broadcast packets that are destined for
the directly connected network and are received from another subnet to support Wake on LAN.
Wake on LAN sends the directed broadcasts to wake up the hosts on the target network.
Examples
# Enable VLAN-interface 2 to receive and forward directed broadcast packets destined for the
directly connected network.
<Sysname> system-view
[Sysname] interface vlan-interface 2
[Sysname-Vlan-interface2] ip forward-broadcast
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