Disable Unused Services

Posted: 1st August 2020 by ccna7guru in ITN
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Cisco routers and switches start with a list of active services that may or may not be required in your network. Disable any unused services to preserve system resources, such as CPU cycles and RAM, and prevent threat actors from exploiting these services. The type of services that are on by default will vary depending on the IOS version. For example, IOS-XE typically will have only HTTPS and DHCP ports open. You can verify this with the show ip ports all command, as shown in the example.

show ip ports all
show ip ports all 

IOS versions prior to IOS-XE use the show control-plane host open-ports command. We mention this command because you may see it on older devices. The output is similar. However, notice that this older router has an insecure HTTP server and Telnet running. Both of these services should be disabled. As shown in the example, disable HTTP with the no ip http server global configuration command. Disable Telnet by specifying only SSH in the line configuration command, transport input ssh.

show control-plane host open-ports
show control-plane host open-ports