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Cisco IOS Firewall

From Ever changing code

This is about configuring firewall on Cisco IOS - not ASA. Base line router here is Cisco 1941/K9 platform with following softwre vesion: (C1900-UNIVERSALK9-M), Version 15.2(4)M4, RELEASE SOFTWARE (fc2).

License

Cisco1941/K9 arrives with universal image but CBAC and firewall features require securityk9 feature to be enabled to make it work.

Enable security9 feature

show license feature
Feature name             Enforcement  Evaluation  Subscription   Enabled  RightToUse
ipbasek9                 no           no          no             yes      no
securityk9               yes          yes         no             no       yes
datak9                   yes          yes         no             no       yes
SSL_VPN                  yes          yes         no             no       yes
ios-ips-update           yes          yes         yes            no       yes
hseck9                   yes          no          no             no       no
WAAS_Express             yes          yes         no             no       yes
r1(config)#license boot module c1900 technology-package securityk9

Then write configuration and reload the router.

Verify the license features.
show license feature
Feature name             Enforcement  Evaluation  Subscription   Enabled  RightToUse
ipbasek9                 no           no          no             yes      no
securityk9               yes          yes         no             yes      yes
datak9                   yes          yes         no             no       yes
SSL_VPN                  yes          yes         no             no       yes
ios-ips-update           yes          yes         yes            no       yes
hseck9                   yes          no          no             no       no
WAAS_Express             yes          yes         no             no       yes
show license detail securityk9
Feature: securityk9                      Period left: 8  weeks 3  days
Index: 1        Feature: securityk9                        Version: 1.0
        License Type: EvalRightToUse
        License State: Active, In Use
            Evaluation total period: 8  weeks 4  days
            Evaluation period left: 8  weeks 3  days
            Period used: 10 minutes 48 seconds
            Transition date: Feb 06 2014 11:34:49
        License Count: Non-Counted
        License Priority: Low
        Store Index: 0
        Store Name: Built-In License Storage

After reboot you will see during booting sequence:

Installed image archive
Cisco CISCO1941/K9 (revision 1.0) with 487424K/36864K bytes of memory.
Processor board ID **********
6 Gigabit Ethernet interfaces
3 terminal lines
1 Virtual Private Network (VPN) Module
2 Cellular interfaces

Disable security9 feature

r1(config)#license boot module c1900 technology-package securityk9 disable

Then write configuration and reload the router. Verify the license features using show commands from the previous point.

CBAC - BAC - Context Based Access Control

WIP....

license boot module c1900 technology-package securityk9

ip inspect name REMEMBER tcp
ip inspect name REMEMBER udp
ip inspect name REMEMBER icmp


ip access-list extended INTERNET-IN
 permit udp any eq domain any
 deny   ip any any log

interface GigabitEthernet0/0
 ip address dhcp
 ip access-group INTERNET-IN in
 ip nat enable
 ip inspect REMEMBER out
 duplex auto
 speed auto

References