67 UDP-H ELPER CONFIGURATIONIntroduction toUDP-HelperUDP-Helper is designed to relay specified UDP broadcast packets. It enables adevice to operate as a UDP packet relay. That is, it can convert UDP broadcastpackets into unicast packets and forward them to a specified server.Normally, all the received UDP broadcast packets are passed to the UDP module.With the UDP-Helper function enabled, the device checks the destination portnumbers of the received UDP broadcast packets and duplicates those with theirdestination port numbers being that configured for UDP-Helper to the UDP-Helpermodule. The UDP-helper module in turn modifies the destination IP addresses ofthe packets and then sends the packet to the specified destination server.n The DHCP Relay module uses UDP port 67 and 68 to relay BOOTP/DHCP broadcastpackets, so do not use port 67 and 68 as UDP-Helper destination ports.With UDP-Helper enabled, the device relays the UDP broadcast packets whosedestination ports are one of the six UDP ports list in Table 591 by default.ConfiguringUDP-HelperTable 591 List of default UDP portsProtocol UDP port numberTrivial file transfer protocol (TFTP) 69Domain name system (DNS) 53Time service 37NetBIOS name service (NetBIOS-NS) 137NetBIOS datagram service (NetBIOS-DS) 138TACACS (terminal access controller access control system) 49Table 592 Configure UDP-HelperOperation Command DescriptionEnter system view system-view -Enable UDP-Helper udp-helper enable RequiredUDP-Helper is disabled bydefault
