Interface configuration does not include the console or auxiliary ports. These interfaces, along with settings related to telnet sessions, are configured using the line command. Again accessed via global configuration mode, these ports and settings are also configured using their names, though with a slightly different syntax.
Console. The configuration of a router’s console port is accessed using the command line console 0. Accessing the line configuration for the console port allows you to configure settings such as a password.
Auxiliary. The auxiliary port’s configuration is accessed using the command line auxiliary 0.
Virtual Terminals. Telnet ports are also known as virtual terminals. Different routers will allow varying numbers of simultaneous telnet sessions, depending upon their IOS version. Telnet connections occur over an existing hardware port, such as a correctly configured Ethernet or serial interface. However, properties relating to telnet sessions are set by configuring virtual or vty ports. The command to configure virtual terminal ports is line vty, followed by the number (or numbers) of the ports that you wish to configure.
To access a line configuration, you must already be in global configuration mode. In the example below, we are accessing the line configuration of the console port.
Enter configuration commands, one per line. End with CNTL/Z.
toronto-1(config)#line console 0
Notice the prompt has changed to toronto-1(config-line)#. Again, it’s up to you to remember which line you just accessed. We’ll look at the actual configuration of line properties (and specifically setting passwords) shortly.