How to Configure a Firewall on Cisco 2821?

The Cisco 2821 router can be configured with terminal

emulation software.

The Cisco 2821 router comes equipped with a software-based firewall.

To configure the firewall on a Cisco 2821, you must be familiar with

Cisco's security-based commands to restrict access across the network.

Administrative privileges and terminal emulation software are necessary

to complete this task.

Things You'll Need

Terminal emulation software

RS-232 serial cable

Cisco router with IOS firewall

Instructions to Configure a Firewall on Cisco 2821 Router

1. Connect the router directly to the administrator workstation using an

RS-232 cable.

2. Use the router's installation CD to install and open the terminal

emulation software. If you prefer to use a third-party emulation

software, that is acceptable.

3. Turn on the router and the initial boot sequence will begin. If the

router has been previously configured, a prompt with the username will

appear, otherwise, the prompt will appear as "Router>."

4. Type "enable" and press "Enter." Type in the router's password when

the password prompt appears.

5. Type "conf t" and press "Enter." This will put the router into global

configuration mode. The prompt will change to "Router (config) #."

6. Type "ip inspect?" and press "Enter." If the router is configured with

the Cisco IOS software, a list of commands will appear that are

specifically designed for configuring your router. If the computer displays

"% Unrecognized Command," then you will need to download and install

the Cisco IOS software (see Resources).

7. Use the list of available commands to configure your router. For

examples of router configurations, navigate your browser to the Cisco

website (see Resources).

8. Type "CNTL/Z" and press "Enter" once the configuration process is

complete. This will return the terminal emulation software back to

privileged mode.

9. Type "show ip route" and press "Enter." A list of all neighboring IP

addresses will be displayed, indicating that the configuration is complete

and the router is communicating with known workstations.

10. Type "show running-config" and press "Enter." Your new running

configuration will display.

11. Type "copy running-config startup-config" and press "Enter." This will

copy your current configuration to your start-up configuration and save it

to the router's memory.

Tips & Warnings

If you have never configured a router, this task can become

frustrating in a hurry. If you are not sure of your ability to

configure your router, it is best to contact a qualified network

administrator to help you.