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ccna online pdf ebook free download.By default, the switch or router opens various services, some of which may cause security risks, so you can turn off unnecessary services from the security point of view without affecting the function of the network equipment.S1 (config)#interface range fa0/l-9,fa0/12-24,gi0/l-2 S1 (config-if-range)#shutdownShutdown the switch ports that are not in use S1 (config-if^range)#switchportmode access Port is configured in access mode to prevent VLAN hopping attacks S1 (config-if^range^exit Sl(config)#no cdp runGlobally disable the CDP function, CDP protocol is Cisco's neighbor discovery protocol S1 (config)#interface fastEthernet 0/1 Sl( config-if)#no cdp enable Disables the CDP function for a specific portChapter 20 Network Security and Monitoring . 392 .Sl(config)#no lldp run Globally disable the LLDP function. the LLDP protocol is the standard neighbor discovery protocol.S1 (config)#interface fastEthernet 0/1 Sl(config-if)#no lldp receive Disable LLDP receive function for a specific port S1 (config-if)#no lldp transmit Disable LLDP transmit function for a specific port Sl(config-if)#exit Sl(config-if)#no ip source-route Disable source-based routing function. config-if)#exit Sl(config)#no ip source-routedisables the source-based routing function, which allows the user to specify the forwarding path in the outgoing IP packets Sl(config)#no ip http serverdisables the HTTP service function, which prevents the user from using the web browser Configure the switch Sl(config)#no service tcp-small-servers to shut down services with TCP port number less than or equal to 19, for example, datetimev echo> chargen, etc. Sl(config)#no service udp-small-servers to shut down services with TCP port number less than or equal to 19. UDP port number less than or equal to 19 Sl(config)#no service finger Shut down the finger service, which is mainly used to query the online user, operating system type and buffer overflow of the remote host, and other user details.Sl(config)#no service dhcpDisable DHCP service, and enable it only if you really need to provide DHCP service Sl(config)#iio ip name-serverDo not configure DNS server for the switch server address Sl(config)#no ip domain-lookup Turn off DNS resolution Sl(config)#no service config// Turn off the switch's ability to look up configuration files on the network Sl(config)#no snmp-server Turn off the SNMP service and delete all SNMP-related configurations20.4.2 Experiment 2: Enabling HTTPS ServiceThrough this experiment, you can grasp: 1. the role of HTTPS service. 2. 2. The configuration of the HTTPS service for verification.2. Experiment TopologyThe experimental topology is shown in Figure 20.2.