2-17To improve security and avoid malicious attack to the unused sockets, S5500-EI Ethernet switchesprovide the following functions:z UDP port 67 and UDP port 68 ports used by DHCP are enabled only when DHCP is enabled.z UDP port 67 and UDP port 68 ports are disabled when DHCP is disabled.The corresponding implementation is as follows:z After a DHCP interface address pool is created by executing the dhcp select interface command,UDP port 67 and UDP port 68 ports used by DHCP are enabled.z After a DHCP interface address pool is deleted by executing the undo dhcp select interfacecommand and all other DHCP functions are disabled, UDP port 67 and UDP port 68 ports used byDHCP are disabled accordingly.Configuring an Address Allocation Mode for an Interface Address PoolIP addresses of an interface address pool can be statically bound to DHCP clients or dynamicallyallocated to DHCP clients.Configuring the static IP address allocation modeSome DHCP clients, such as WWW servers, need fixed IP addresses. This is achieved by binding IPaddresses to the MAC addresses of these DHCP clients. When such a DHCP client applies for an IPaddress, the DHCP server finds the IP address corresponding to the MAC address of the DHCP client,and then assigns the IP address to the DHCP client.When some DHCP clients send DHCP-DISCOVER packets to the DHCP server to apply for IPaddresses, they construct client IDs and add them in the DHCP-DISCOVER packets. The DHCP serverfinds the corresponding IP addresses based on the client IDs and assigns them to the DHCP clients.Follow these steps to configure the static IP address allocation mode:To do… Use the command… RemarksEnter system view system-view —Enter interface view interface interface-typeinterface-number —Configure static bindingdhcp server static-bind ip-addressip-address { client-identifierclient-identifier | mac-addressmac-address }RequiredBy default, staticbinding is notconfigured.
