161Optimizing IP performanceA customized configuration can help optimize overall IP performance. This chapter describes varioustechniques you can use to customize your installation.Enabling an interface to receive and forwarddirected broadcasts destined for the directlyconnected networkA directed broadcast packet is destined for all hosts on a specific network. In the destination IP addressof the directed broadcast, the network ID identifies the target network, and the host ID is made up of allones.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, aninterface must receive and send such directed broadcast packets to support UDP helper and Wake onLAN.This task enables an interface to accept directed broadcast packets that are destined for and receivedfrom the directly connected network to support UDP helper, which converts the directed broadcasts tounicasts and forwards them to a specific server.The task also enables the interface to forward directed broadcast packets that are destined for thedirectly connected network and are received from another subnet to support Wake on LAN, which sendsthe directed broadcasts to wake up the hosts on the target network.Configuration procedureTo enable an interface to receive and forward directed broadcasts destined to the directly connectednetwork:Step Command Remarks1. Enter system view. system-view N/A2. Enter interface view. interface interface-typeinterface-number N/A3. Enable the interface to receiveand forward directedbroadcasts destined for thedirectly connected network.ip forward-broadcastBy default, an interface cannotreceive or forward directedbroadcasts destined for the directlyconnected network.
