To clear your question, there is no " build in " firewall for cisco 3600 router. It's the image that you run on this router support IOS firewall feature set.
The feature set you are looking for is IP/FW. (IP/FW/IDS)
Also when you do show version,
"c3600-io3-mz.122-15.T7.bin" , " o " is the one for firewall.
The concept for IOS firewall is to apply access list to outside interface for inbound direction with the rule deny ip any any, which will deny all the traffic coming into the network. and apply ip inspect to either inside interface for inbound direction or outside intreface for outbound direction to allow the return traffic initiate from inside to come back in.
Basically, it's all dependant on the feature set of your router. You will need to purchase the firewall feature set for your router. What you are looking to buy is SMARTnet for your 3600 with IOS upgrades or the software feature set you are looking for. In the UK, the IP/FW feature set IOS costs about £550 and the part number is CD36-CH-12.x.x where x.x relates to the most current IOS version. Your other option is to get SMARTnet CON-SW-VPKG7 (3620) or 10 (3640) or 13 (3660) which will cost between £300 and £700 depending on which model you need it for, however, this will give you unlimited software feature upgrades for the whole year.
BenefitsDocumentationPrerequisiteImage Download LinksLimitationsSupported PlatformsLicense RequirementsTopologyStep-By-Step ConfigurationConfigure Virtual ServiceActivate the virtual service and configure guest IPsConfiguring UTD (Service Plane)Configurin...
Login to the FXOS chassis manager.
Direct your browser to https://hostname/, and log-in using the user-name and password.
Go to Help > About and check the current version:
Check the current version availa...
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...