Commands for line configuration
These are to be used while setting up the router’s line connections. The same prompt is used for the console line, the vty line, and the auxiliary line, which can cause some confusion. Depending on the command that was sent in global configuration mode, i.e. – determine which one you are working on.
- router(config)# line aux 0
- router(config)# line console 0
- router(config)# line vty 0 4 in
You can only configure one type of line connection at a time; to configure another, you must return to the global configuration mode and choose the appropriate line type as described above.
| Command prompt | Available commands | Comments |
|---|---|---|
| router(config-line)# | exec-timeout | To configure the console time out |
| router(config-line)# | logging synchronous | This command disables console pop-up messages. |
| router(config-line)# | line vty 0 ? | To determine the number of available vty lines |
| router(config-line)# | login | To ask for a login that is valid for aux, console, and vty |
| router(config-line)# | password | Set a password that is valid for the aux, console, and vty |
| router(config-line)# | no login | Risky – this command says that a password is not necessary and is valid for vty |
Cisco iOS Command Hierarchy
The operating system that Cisco uses in many of its products is called Cisco IOS, and you can communicate with it using a command line shell (or Command Line Interface or CLI, as Cisco nomenclature calls it). You have access to about 2000 different commands if you count the commands for many advanced routers and wireless items. The basic commands available in the IOS Cisco CLI used by the router are described here. Some Cisco IOS commands allow you to perform more than one action. You can also navigate up and down the hierarchy of IOS configuration levels (or modes). Some of the various levels are shown below:
Note: Here we are talking about iOS in general and not to a specific version. So not all iOS versions support all the commands listed here, and certain iOS versions contain additional commands not included in this list. Also, note that PIX line of products was originally acquired by Cisco and is not manufactured, so it has (or had) its own operating system. Although some PIX operating system command line shells were eventually merged into the Cisco iOS CLI. Finally, many basic commands have multiple modes.