Accessing the CLI Using a Router Console
Cisco 1100 series routers have console port with modem support.
The following sections describe the main methods of accessing the router:
Accessing the CLI Using a Directly-Connected Console
The CON port is an EIA/TIA-232 asynchronous, serial connection with no-flow control and an RJ-45 connector. The CON port is located on the front panel of the chassis.
The following sections describe the procedure to access the control interface:
Connecting to the Console Port
Procedure
Step 1 |
Configure your terminal emulation software with the following settings:
|
Step 2 |
Connect to the CON port using the RJ-45-to-RJ-45 cable and the RJ-45-to-DB-25 DTE adapter or the RJ-45-to-DB-9 DTE adapter (labeled Terminal). |
Use the Console Interface
Procedure
Step 1 |
Enter the following command: Router > enable
|
Step 2 |
(Go to Step 3 if the enable password has not been configured.) At the password prompt, enter your system password:
When your password is accepted, the privileged EXEC mode prompt is displayed.
You now have access to the CLI in privileged EXEC mode and you can enter the necessary commands to complete your desired tasks. |
Step 3 |
If you enter the setup command, see “Using Cisco Setup Command Facility” in the “Initial Configuration” section of the Hardware Installation Guide for the Cisco 1100 Series Integrated Services Router. |
Step 4 |
To exit the console session, enter the exit command:
|
Using SSH to Access Console
Secure Shell (SSH) is a protocol which provides a secure remote access connection to network devices. To enable SSH support on the device:
Procedure
Step 1 |
Configure the hostname:
Here, host name is the router hostname or IP address. |
Step 2 |
Configure the DNS domain of the router:
|
Step 3 |
Generate an SSH key to be used with SSH:
|
Step 4 |
By default, the vtys? transport is Telnet. In this case, Telnet is disabled and only SSH is supported:
|
Step 5 |
Create a username for SSH authentication and enable login authentication:
|
Step 6 |
Verify remote connection to the device using SSH. |
Accessing the CLI from a Remote Console Using Telnet
The following topics describe the procedure to access the CLI from a remote console using Telnet:
Preparing to Connect to the Router Console Using Telnet
To access the router remotely using Telnet from a TCP/IP network, configure the router to support virtual terminal lines using the line vty global configuration command. Configure the virtual terminal lines to require users to log in and specify a password.
See the Cisco IOS Terminal Services Command Reference document for more information about the line vty global configuration command.
To prevent disabling login on a line, specify a password with the password command when you configure the login command.
If you are using authentication, authorization, and accounting (AAA), configure the login authentication command. To prevent disabling login on a line for AAA authentication when you configure a list with the login authentication command, you must also configure that list using the aaa authentication login global configuration command.
For more information about AAA services, see the Cisco IOS XE Security Configuration Guide: Secure Connectivity and the Cisco IOS Security Command Reference documents. For more information about the login line-configuration command, see the Cisco IOS Terminal Services Command Reference document.
In addition, before you make a Telnet connection to the router, you must have a valid hostname for the router or have an IP address configured on the router. For more information about the requirements for connecting to the router using Telnet, information about customizing your Telnet services, and using Telnet key sequences, see the Cisco IOS Configuration Fundamentals Configuration Guide.
Using Telnet to Access a Console Interface
Procedure
Step 1 |
From your terminal or PC, enter one of the following commands:
Here, host is the router hostname or IP address, port is a decimal port number (23 is the default), and keyword is a supported keyword. For more information about these commands, see the Cisco IOS Terminal Services Command Reference document.
The following example shows how to use the telnet command to connect to a router named router:
|
||
Step 2 |
Enter your login password:
|
||
Step 3 |
From user EXEC mode, enter the enable command:
|
||
Step 4 |
At the password prompt, enter your system password: Password: enablepass
|
||
Step 5 |
When the enable password is accepted, the privileged EXEC mode prompt is displayed: Router#
|
||
Step 6 |
You now have access to the CLI in privileged EXEC mode and you can enter the necessary commands to complete your desired tasks. |
||
Step 7 |
To exit the Telnet session, use the exit or logout command. Router# logout
|
Accessing the CLI from a Remote Console Using a Modem
To access the router remotely using a modem through an asynchronous connection, connect the modem to the port. For more information, see the "Configuring Console Port for Modem Connection" section.
Accessing the CLI from a Micro USB Serial Console Port
The router provides an additional mechanism for configuring the system: a micro USB serial console that supports remote administration of the router using a micro USB-compliant cable. See the "Connecting to a Console Terminal or Modem" section in the Hardware Installation Guide for the Cisco 1100 Series Integrated Services Router.
Keyboard Shortcuts
Commands are not case sensitive. You can abbreviate commands and parameters if the abbreviations contain enough letters to be different from any other currently available commands or parameters.
The following table lists the keyboard shortcuts for entering and editing commands.
Key Name |
Purpose |
---|---|
Ctrl-B or the Left Arrow key1 |
Move the cursor back one character. |
Ctrl-F or the Right Arrow key1 |
Move the cursor forward one character. |
Ctrl-A |
Move the cursor to the beginning of the command line. |
Ctrl-E |
Move the cursor to the end of the command line. |
Esc B |
Move the cursor back one word. |
Esc F |
Move the cursor forward one word. |
Using the History Buffer to Recall Commands
The history buffer stores the last 20 commands you entered. History substitution allows you to access these commands without retyping them, by using special abbreviated commands.
The following table lists the history substitution commands.
Command |
Purpose |
---|---|
Ctrl-P or the Up Arrow key1 |
Recalls commands in the history buffer, beginning with the most recent command. Repeat the key sequence to recall successively older commands. |
Ctrl-N or the Down Arrow key1 |
Returns to more recent commands in the history buffer after recalling commands with Ctrl-P or the Up Arrow key. |
Router# show history |
While in EXEC mode, lists the last few commands you entered. |
1 The arrow keys function only on ANSI-compatible terminals such as VT100s. |
Understanding Command Modes
The command modes available in Cisco IOS XE are the same as those available in traditional Cisco IOS. Use the CLI to access Cisco IOS XE software. Because the CLI is divided into many different modes, the commands available to you at any given time depend on the mode that you are currently in. Entering a question mark (?) at the CLI prompt allows you to obtain a list of commands available for each command mode.
When you log in to the CLI, you are in user EXEC mode. User EXEC mode contains only a limited subset of commands. To have access to all commands, you must enter privileged EXEC mode, normally by using a password. From privileged EXEC mode, you can issue any EXEC command—user or privileged mode—or you can enter global configuration mode. Most EXEC commands are one-time commands. For example, show commands show important status information, and clear commands clear counters or interfaces. The EXEC commands are not saved when the software reboots.
Configuration modes allow you to make changes to the running configuration. If you later save the running configuration to the startup configuration, these changed commands are stored when the software is rebooted. To enter specific configuration modes, you must start at global configuration mode. From global configuration mode, you can enter interface configuration mode and a variety of other modes, such as protocol-specific modes.
ROM monitor mode is a separate mode used when the Cisco IOS XE software cannot load properly. If a valid software image is not found when the software boots or if the configuration file is corrupted at startup, the software might enter ROM monitor mode.
The following table describes how to access and exit various common command modes of the Cisco IOS XE software. It also shows examples of the prompts displayed for each mode.
Command Mode |
Access Method |
Prompt |
Exit Method |
---|---|---|---|
User EXEC |
Log in. |
|
Use the logout command. |
Privileged EXEC |
From user EXEC mode, use the enable command. |
|
To return to user EXEC mode, use the disable command. |
Global configuration |
From privileged EXEC mode, use the configure terminal command. |
|
To return to privileged EXEC mode from global configuration mode, use the exit or end command. |
Interface configuration |
From global configuration mode, specify an interface using an interface command. |
|
To return to global configuration mode, use the exit command. To return to privileged EXEC mode, use the end command. |
Diagnostic |
The router boots up or accesses diagnostic mode in the following scenarios:
|
|
If failure of the Cisco IOS process is the reason for entering diagnostic mode, the Cisco IOS problem must be resolved and the router rebooted to get out of diagnostic mode. If the router is in diagnostic mode because of a transport-map configuration, access the router through another port or by using a method that is configured to connect to the Cisco IOS CLI. |
ROM monitor |
From privileged EXEC mode, use the reload EXEC command. Press the Break key during the first 60 seconds while the system is booting. |
|
To exit ROM monitor mode, manually boot a valid image or perform a reset with autoboot set so that a valid image is loaded. |
Understanding Diagnostic Mode
The router boots up or accesses diagnostic mode in the following scenarios:
-
The IOS process or processes fail, in some scenarios. In other scenarios, the system resets when the IOS process or processes fail.
-
A user-configured access policy was configured using the transport-map command that directs the user into the diagnostic mode.
-
A send break signal (Ctrl-C or Ctrl-Shift-6) was entered while accessing the router, and the router was configured to enter diagnostic mode when a break signal was sent.
In the diagnostic mode, a subset of the commands that are available in user EXEC mode are made available to the users. Among other things, these commands can be used to:
-
Inspect various states on the router, including the IOS state.
-
Replace or roll back the configuration.
-
Provide methods of restarting the IOS or other processes.
-
Reboot hardware, such as the entire router, a module, or possibly other hardware components.
-
Transfer files into or off of the router using remote access methods such as FTP, TFTP, and SCP.
The diagnostic mode provides a more comprehensive user interface for troubleshooting than previous routers, which relied on limited access methods during failures, such as ROMMON, to diagnose and troubleshoot Cisco IOS problems. The diagnostic mode commands can work when the Cisco IOS process is not working properly. These commands are also available in privileged EXEC mode on the router when the router is working normally.
Getting Help
Entering a question mark (?) at the CLI prompt displays a list of commands available for each command mode. You can also get a list of keywords and arguments associated with any command by using the context-sensitive help feature.
To get help that is specific to a command mode, a command, a keyword, or an argument, use one of the following commands.
Command |
Purpose |
||
---|---|---|---|
|
Provides a brief description of the help system in any command mode. |
||
|
Provides a list of commands that begin with a particular character string.
|
||
|
Completes a partial command name. |
||
|
Lists all the commands that are available for a particular command mode. |
||
|
Lists the keywords or arguments that you must enter next on the command line.
|
Finding Command Options: Example
This section provides information about how to display the syntax for a command. The syntax can consist of optional or required keywords and arguments. To display keywords and arguments for a command, enter a question mark (?) at the configuration prompt or after entering a part of a command followed by a space. The Cisco IOS XE software displays a list and brief descriptions of the available keywords and arguments. For example, if you are in global configuration mode and want to see all the keywords and arguments for the arap command, you should type arap ?.
The <cr> symbol in command help output stands for carriage return. On older keyboards, the carriage return key is the Return key. On most modern keyboards, the carriage return key is the Enter key. The <cr> symbol at the end of command help output indicates that you have the option to press Enter to complete the command and that the arguments and keywords in the list preceding the <cr> symbol are optional. The <cr> symbol by itself indicates that no more arguments or keywords are available, and that you must press Enter to complete the command.
The following table shows examples of using the question mark (?) to assist you in entering commands.
Command |
Comment |
---|---|
|
Enter the enable command and password to access privileged EXEC commands. You are in privileged EXEC mode when the prompt changes to a “ #
” from the “ > ”, for example, |
|
Enter the configure terminal privileged EXEC command to enter global configuration mode. You are in global configuration mode when the prompt changes
to |
|
Enter interface configuration mode by specifying the interface that you want to configure, using the interface GigabitEthernet global configuration command. Enter ? to display what you must enter next on the command line. When the <cr> symbol is displayed, you can press Enter to complete the command. You are in interface configuration mode when the prompt changes to |
|
Enter ? to display a list of all the interface configuration commands available for the interface. This example shows only some of the available interface configuration commands. |
|
Enter the command that you want to configure for the interface. This example uses the ip command. Enter ? to display what you must enter next on the command line. This example shows only some of the available interface IP configuration commands. |
|
Enter the command that you want to configure for the interface. This example uses the ip address command. Enter ? to display what you must enter next on the command line. In this example, you must enter an IP address or the negotiated keyword. A carriage return (<cr>) is not displayed. Therefore, you must enter additional keywords or arguments to complete the command. |
|
Enter the keyword or argument that you want to use. This example uses the 172.16.0.1 IP address. Enter ? to display what you must enter next on the command line. In this example, you must enter an IP subnet mask. <cr> is not displayed. Therefore, you must enter additional keywords or arguments to complete the command. |
|
Enter the IP subnet mask. This example uses the 255.255.255.0 IP subnet mask. Enter ? to display what you must enter next on the command line. In this example, you can enter the secondary keyword, or you can press Enter. <cr> is displayed. Press Enter to complete the command, or enter another keyword. |
|
Press Enter to complete the command. |
Using the no and default Forms of Commands
Almost every configuration command has a no form. In general, use the no form to disable a function. Use the command without the no keyword to re-enable a disabled function or to enable a function that is disabled by default. For example, IP routing is enabled by default. To disable IP routing, use the no ip routing command; to re-enable IP routing, use the ip routing command. The Cisco IOS software command reference publications provide the complete syntax for the configuration commands and describe what the no form of a command does.
Many CLI commands also have a default form. By issuing the <command> default command-name, you can configure the command to its default setting. The Cisco IOS software command reference publications describe the function from a default form of the command when the default form performs a different function than the plain and no forms of the command. To see what default commands are available on your system, enter default ? in the appropriate command mode.
Using the factory reset Commands
The factory reset commands are used to remove all the customer specific data on a router/switch that has been added. The data can be configuration, log files, boot variables, core files, and so on.
The factory-reset all command erases the bootflash, nvram, rommon variables, licenses, and logs.
Router#factory-reset all
The factory reset operation is irreversible for all operations. Are you sure? [confirm] *Enter*
*May 12 09:55:45.831: %SYS-5-RELOAD: Reload requested by Exec. Reload Reason: Factory Reset.
***Return to ROMMON Prompt
Saving Configuration Changes
Use the copy running-config startup-config command to save your configuration changes to the startup configuration so that the changes will not be lost if the software reloads or a power outage occurs. For example:
Router# copy running-config startup-config
Building configuration...
It may take a few minutes to save the configuration. After the configuration has been saved, the following output is displayed:
[OK]
Router#
This task saves the configuration to the NVRAM.
Managing Configuration Files
The startup configuration file is stored in the nvram: file system and the running configuration files are stored in the system: file system. This configuration file storage setup is also used on several other Cisco router platforms.
As a matter of routine maintenance on any Cisco router, users should back up the startup configuration file by copying the startup configuration file from NVRAM to one of the router’s other file systems and, additionally, to a network server. Backing up the startup configuration file provides an easy method of recovering the startup configuration file if the startup configuration file in NVRAM becomes unusable for any reason.
The copy command can be used to back up startup configuration files.
For more detailed information on managing configuration files, see the “Managing Configuration Files” section in the Cisco IOS XE Configuration Fundamentals Configuration Guide.
Filtering Output from the show and more Commands
You can search and filter the output of show and more commands. This functionality is useful if you need to sort through large amounts of output or if you want to exclude output that you need not see.
To use this functionality, enter a show or more command followed by the “pipe” character ( | ); one of the keywords begin, include, or exclude; and a regular expression on which you want to search or filter (the expression is case sensitive):
show command | {append | begin | exclude | include | redirect | section | tee} regular-expression
The output matches certain lines of information in the configuration file.
Example
In this example, a modifier of the show interface command (include protocol) is used to provide only the output lines in which the expression protocol is displayed:
Router# show interface | include protocol
GigabitEthernet0/0/0 is administratively down, line protocol is down
0 unknown protocol drops
GigabitEthernet0/0/1 is administratively down, line protocol is down
0 unknown protocol drops
GigabitEthernet0/0/2 is administratively down, line protocol is down
0 unknown protocol drops
GigabitEthernet0/0/3 is administratively down, line protocol is down
0 unknown protocol drops
GigabitEthernet0 is up, line protocol is up
0 unknown protocol drops
Loopback0 is up, line protocol is up
0 unknown protocol drops
Powering Off a Router
Before you begin
The router can be safely turned off at any time by moving the router’s power supply switch to the Off position. However, any changes to the running config since the last WRITE of the config to the NVRAM is lost.
Ensure that any configuration needed after startup is saved before powering off the router. The copy running-config startup-config command saves the configuration in NVRAM and after the router is powered up, the router initializes with the saved configuration.
Finding Support Information for Platforms and Cisco Software Images
The Cisco IOS XE software is packaged in feature sets consisting of software images that support specific platforms. The group of feature sets that are available for a specific platform depends on which Cisco software images are included in a release. To identify the set of software images available in a specific release or to find out if a feature is available in a given Cisco IOS XE software image, you can use Cisco Feature Navigator or see the Release Notes for Cisco IOS XE.
Using Cisco Feature Navigator
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator is a tool that enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To use the navigator tool, an account on Cisco.com is not required.
Using Software Advisor
Cisco maintains the Software Advisor tool. See Tools and Resources. Use the Software Advisor tool to see if a feature is supported in a Cisco IOS XE release, to locate the software document for that feature, or to check the minimum software requirements of Cisco IOS XE software with the hardware installed on your router. You must be a registered user on Cisco.com to access this tool.
Using Software Release Notes
See the Release Notes document for the Cisco 4000 Series for information about the following:
-
Memory recommendations
-
Open and resolved severity 1 and 2 caveats
Release notes are intended to be release-specific for the most current release, and the information provided in these documents may not be cumulative in providing information about features that first appeared in previous releases. For cumulative feature information, refer to the Cisco Feature Navigator at: http://www.cisco.com/go/cfn/.
CLI Session Management
An inactivity timeout is configurable and can be enforced. Session locking provides protection from two users overwriting changes that the other has made. To prevent an internal process from using all the available capacity, some spare capacity is reserved for CLI session access. For example, this allows a user to remotely access a router.
Information About CLI Session Management
An inactivity timeout is configurable and can be enforced. Session locking provides protection from two users overwriting changes that each other has made. To prevent an internal process from using all the available capacity, some spare capacity is reserved for CLI session access. For example, this allows a user to remotely access the router.
Changing the CLI Session Timeout
Procedure
Step 1 |
Enters global configuration mode |
Step 2 |
|
Step 3 |
The value of |
Step 4 |
" Idle Session " .
|
Locking a CLI Session
Before you begin
To configure a temporary password on a CLI session, use the lock command in EXEC mode. Before you can use the lock command, you need to configure the line using the lockable command. In this example the line is configured as lockable, and then the lock command is used and a temporary password is assigned.
Procedure
Step 1 |
Enters global configuration mode. |
Step 2 |
Enter the line upon which you want to be able to use the lock command.
Router(config)# line console 0
|
Step 3 |
Enables the line to be locked. |
Step 4 |
|
Step 5 |
|