Basic Cisco Router Configuration Step

Different IP networks cannot communicate with each other without a router. Routers do this job successfully by sending a packet from one IP network to another IP network using routing. Before using the router, some basic configuration is required. This article covers the initial router configuration. We will use Cisco Packet Tracer for simulation and configuration. Cisco Packet Tracer is network simulator software that can be downloaded from the following links.

Cisco Packet Instructor 

Cisco Packet Tracer 7.0

You can also use network simulator software such as Boson and GNS. You may also use an actual Cisco device in place of simulators. When a new Cisco router boots up for the first time or no configuration is found, it asks the user if they want to run through a list of prompts to configure the router. Most Cisco professionals ignore this initial setup wizard because of the lack of a better word.  They also like to configure the router manually. The initial setup mode screen is shown in the figure below. This mode is also known as the setup mode.

When a Cisco router is initially booted, and there is nothing configured, the only thing that is needed to configure the router is a console cable. Once a connection established the basic configuration of the device can be made, all initial configurations will be covered next in this article. The first prompt, if the user says “no” to the setup wizard, the user will be a user exec mode prompt, as shown below:

Router>

As we also learned in the previous article, Cisco IOS supports various command-line interface modes. The following are the main command modes.

  • User EXEC Mode
  • Privileged EXEC Mode
  • Global Configuration Mode
  • Interface Configuration Mode
  • Sub-Interface Configuration Mode
  • Setup Mode
  • ROM Monitor Mode

To navigate between these modes, we need to execute specific commands:

router configuration

How to Change Default Hostname

Changing the name of the router differentiates the device from others. By default, the name “Router” is configured on each router. So, we can change the router’s default name and configure any name on the router. To do this, command <hostname name> will be used in global configuration mode, For example, as shown in the figure below:

How to configure the Password on Cisco router

Considering the importance of the router, the password is essential for each router in the network. The router supports multiple networks and can connect various lines for management, so we need to secure each management line:

Secure Console Port (line console)

Console and Telnet are the most commonly used line types for Cisco routers. The console line allows a local user to access the router when physically connected to the console port. By default, the console port is not configured with any password, so any user with physical access can connect.  A password can be configured on the console line to block this access. To configure a password, the user must access the console line configuration mode using the ‘line console 0‘ command and issue the ‘password password‘ command, as shown below on the Shahab router:

How to configure telnet and telnet password

We can access the router using telnet when a router has configured at least one interface and the password for telnet. Depending on the model number and IOS software version, the router may also support various numbers of VTY connections. VTY is the name for telnet and SSH connections. By default, only the first five VTY connections are enabled. But when you try to connect them remotely, you will get the following message: “Password required, but none set.” This message gives a warning that the password is not set on VTY lines.

On most Cisco routers, the VTY lines used for telnet connections are labelled from 0 through 4, for a total of 5 lines. The ‘line vty 0 4‘ command is used to gain access to this mode. The following is the procedure to configure telnet access to the router.

How to secure the privileged EXEC mode and encrypt all passwords

We can secure the privileged EXEC mode using the “enable password “command. The Enable Secret command secures the user in privileged mode with the encrypted password. And using the help of “service password-encryption”, we can encrypt all saved password in the configuration file. The method to secure privileged EXEC mode is the following:

How to Configure Login Banner

We can configure two banners on Cisco routers: “MOTD” and “Exec”. The banner exec command is not available in the packet tracer. In packet tracer, we can practice only with the banner MOTD command. Both commands work in the same way. Only the place of a display is different between both commands. An EXEC banner will display after login, and a MOTD banner will display before the login. The following is the procedure for configuring the MOTD banner.

How to enable DNS lookup

We can configure a DNS server for our router; the image below illustrates the configuration steps.

How to turn off the automatic name resolution

The router is set by default to try to resolve any word not listed in the command to a DNS server at address limited broadcast Address 255.255.255.255. Sometimes, it takes longer when we type some wrong words. We can turn this off by using the following command:

How to assign a Local Name to an IP address

We can assign a local name to an IP address. Usually, the hostname is assigned to the IP address.  Once completed, we can use the configured hostname for telnet or ping.

How to Save the Router Configuration

We can save the Router Configuration from user-privileged mode, and we can also save it from global configuration mode, as shown in the figure below:

Apply the same command with “do” and follow the same command in global configuration mode to save the configuration. For example, do write or do copy  running-config startup-config as shown in the figure above