Command IP access-group Use This command is used to apply an access-list to an interface. Syntax Router(config-if)#ip access-group <list> <in or out> Option <auto> automatically determine the duplex mode by checking with the neighbor <in> applies the access-list to inbound traffic on the interface. <out> applies the access-list …

Command shutdown Use This command will administratively disable an interface. Alternatively, you can enable the interface by negating the command using no shutdown. Syntax Router(config-if)#shutdown OR Router(config-if)#no shutdown Example In the below example, we shutdown R1’s Fa0/0 interface and then enable the interface again. R1(config)#int fa0/0 R1(config-if)#shutdown R1(config-if)# …

Command Bandwidth Use This command is used to logically set the bandwidth of an interface. This does not affect the physical speed of the link, it only affects routing protocols and other technologies that use bandwidth as a calculation. Syntax Router(config-if)#bandwidth <kilobits> Example In this example, we change …

Command IP address Use This command is used to set IP addresses on an interface. Syntax R1(config)#ip address <IP address> <subnet mask> <secondary> Options <IP address> IP address for the interface <subnet mask> IP address for the interface <secondary> Sets the IP address as a secondary IP address, …

Command Enable Password Use Sets a non-encrypted password for enable mode on the router. Syntax Router(config)#enable password <WORD> Example In this example the enable password is set on R1. R1(config)#enable password cisco R1(config)# Next the enable password is verified using the show run command. R1(config)#do show run | …

Command IP nat inside source static Use This command is used to specify a map between a specific IP address (and port number if required). Used when you must use only a certain IP address or port such as SMTP. Syntax R1(config)#ip nat inside source static <original IP> …

Command router ospf <process id> Use The router ospf (Open Shortest Path First) command is necessary to enable ospf. OSPF must be enabled before carrying out any of the ospf commands. OSPF was designed to be an Interior Gateway Protocol replacing RIP. Routers that use OSPF check the …

Command Banner motd Use This command is used to set the banner message that is displayed before remote login to the router. Syntax Router(config)#banner motd <char> <TEXT> <char> <char> Can be any character, used to delimit <TEXT> string Example In this example, the banner motd command is used …

Command Interface Loopback Use This command creates a logical interface on the router. These are handy from an administrative perspective because the loopback interface will also stay in a up/up state unless you shutdown the interface. Syntax Router(config)#interface loopback <num> Example In this example, we will create a …

Command Access-list (Extended) Use This command is used to create a list that matches packets on a given criteria. While access-lists are most commonly associated with security, there are numerous uses. Extended lists match on source addresses and destination addresses as well as protocol information. Syntax Router(config)#access-list <100-199 …