October 16, 2018

FMC – An internal error is preventing the system from validating this policy.

Have you ever been working on an access policy in Cisco Firepower Management Center and then seen the following error pop up when you opened or saved a policy: An internal error is preventing the...

Connect Firewall to FMC Through NAT Device

Normally connecting a firewall to a Firepower Management Center server is a short, simple process. This is because a lot of use cases have the FMC and the FTD firewall on the same network....

ERROR: TRACER: NP failed tracing packet

I recently implemented a couple of Cisco Firepower firewalls and have been using the packet-tracer feature to determine which NAT rules were being used for certain traffic for instance. Then, after troubleshooting an issue...

Firepower 4100/9300 – Reset to Factory Default

I recently began working on a project with a Firepower 4100 chassis. When I powered on the appliance I quickly realized that the setup would be different than a normal Firepower device. The console...

Cisco Router IPSec VPN Tunnel Lab (with Video)

This post will cover the creation of an IPSec tunnel between two Cisco routers. If you've ever done one of these on an ASA firewall for instance, you will notice right off the bat...
Remote-Firepower-Firewall-Example-Topology

Add Remote Firepower Firewall to Firepower Management Center

This guide is something that I have seen requests for in multiple places including the Cisco supportforums. I recently had to complete this process for some new Cisco Firepower FTD firewalls so I am...
pmtu-d packet

PMTU-D Packet Greater Than Effective MTU

Nothing special about this post, but I ran into an issue today and wanted to pass along the fix. I've noticed some of my posts that revolve around bug fixes are the most popular,...
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