Configure the Cisco IOS Firewall on a Cisco Router

This article describes how to configure the IOS Firewall on a Cisco router. What should we pay attention to when configuring the firewall? The following article provides detailed answers.

Pre-configuration on R1, R2, and R3

R1 (config) # int e0/0
R1 (config-if) # ip add 172.16.1.1 255.255.255.0
R1 (config-if) # no sh
R1 (config) # ip route 0.0.0.0 0.0.0.0 172.16.1.2 configure Static Routing
R1 (config) # ^ Z
R2 (config) # int e0/0
R2 (config-if) # ip add 172.16.1.2 255.255.255.0
R2 (config-if) # no sh
R2 (config-if) # int e2/0
R2 (config-if) # ip add 192.168.1.2 255.255.255.0
R2 (config-if) # no sh
R3 (config) # int e2/0
R3 (config-if) # ip add 192.168.1.3 255.255.255.0
R3 (config-if) # no sh
R3 (config) # ip route 0.0.0.0 0.0.0.0 192.168.1.2 configure Static Routing
R3 (config) # ^ Z
R3 (config) # li vty 0 4
R3 (config-line) # pass
R3 (config-line) # password cisco
R3 (config-line) # exit