Different IP network 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 it would require some basic Configuration. 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 download from the following links.
You can also use any other network simulator software such as Boson, GNS. You may also use a real Cisco device in place of simulators. When a new Cisco router boots up for the first time or a time when there is no configuration found on the router, it asks the user if they want to run through a list of prompts to configure the router; Most Cisco professional 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 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 see is a user exec mode prompt, as shown below:
As we also learned in the previous article that Cisco IOS supports various command-line interface modes, among those followings, 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:
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 default name of the router 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
Upon the importance of the router, the password is very important for each router in the network. The router supports multiple networks and can connect multiple lines for management and so, we need to secure each management line:
Secure Console Port (line console)
Console and Telnet are the most commonly used line types on a Cisco router. The console line allows a local user to access the router when physically connected to the console port. By default, console port has not configured with any password so any user with physical access can connect. To block this access, a password can be configured on the console line. 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 also configured the password for telnet. Depending on the model number and IOS software version router may also support the various number of VTY connections. VTY is the name for telnet and SSH connection. By default only first five VTYs connections are enabled. But when you try to connect them remotely you will get following message “Password required but none set” This message gives warning that password is not set on VTY lines.
On most Cisco routers the VTY lines used for telnet connections are labelled from 0 through 4 total of 5 lines. The ‘line vty 0 4‘ command used to gain access to this mode. 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. Using the enable secret command secures the user 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 types of the banner on Cisco routers “MOTD” and “Exec” banner. banner exec command is not available in packet tracer. In packet tracer, we can practice only with banner MOTD command. Both commands also work in the same way. Only the place of a display is different between both commands. An EXEC banner will display after login and MOTD banner will display before the login. Following is the procedure to configure 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 that is not a listed in command to a DNS server at address limited broadcast Address 255.255.255.255. Sometimes it takes longer when we type some wrong words. So, we can turn off this 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 this is 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” followed 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