In my company we have Cisco ASA firewall as edge device on the Internet. So outside interface with public IP address and security level 0 and inside interfaces with higher security levels. Standard implementation. Now we need to put Cisco router in front of ASA, so it would be between my ISP and ASA. Router will have three interfaces with public ip addresses. So he will be very visible on the Internet. And because it is a router and not a firewall I am worried about the safety and security of the router. How can I secure and harden the router? Which services and protocols must be shutdown? What are the recommendations?

  • 2
    Cisco has documents on hardening devices; simply search for them. You can also get a license for your router that includes a firewall, including ZBFW.
    – Ron Maupin
    Jun 4, 2018 at 20:22
  • We bought the router without ZBFW license. We only have SEC/K9.
    – John
    Jun 4, 2018 at 20:27
  • You can still get the license to unlock the feature. The code is there, you simply need the license to use it.
    – Ron Maupin
    Jun 4, 2018 at 20:30
  • 3
    In general, ACLs will be all you need, as well as disabling any features you don't actually need.
    – Ricky
    Jun 4, 2018 at 21:40
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Dec 25, 2018 at 8:35

1 Answer 1


The hardening of an equipment dependens on a lot of factors, ie: Protocols, services, features, etc. On this way you could search for the specific cisco hardening documents. THis example is a general purpose document about IOS devices: https://www.cisco.com/c/en/us/support/docs/ip/access-lists/13608-21.html

  • The link provided here is a great guide, but it's very intimidating for someone who is new to this. The highest priority items are locking down the access methods (like disabling telnet), locking down who can access the device (apply an access-list to the vty lines), and ensuring the credentials are strong (uncommon username and strong password). After that comes other things like disabling services (small-servers, finger), logging (syslog would be great), and filtering traffic to the router (applying interface ACLs). Jul 11, 2018 at 18:03

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