I'm trying to find out what the maximum amount of ACE's allowed to be entered in a Single ACL for the ASA5505 with Security + IOS. I've scoured the Internet, searched Cisco documentation and found nothing that would necessarily help me.
What I'm trying to find out is whether denying all IP traffic and only permitting US IP Subnets into my network is feasible or not.I've come up with a list of US IP's to be roughly 45800 subnets (accurate as of last month). So the inbound ACL in a nutshell would be "permit US subnets" "deny anything else"
That will at least keep the scan attacks down to a minimum and if they use proxies from US servers, I can address them as they try to attack my network.
Thanks for the reply. I know at the 20K ACE limit, some ISP Grade routers run out of TCAMs (I believe they were Cisco12ks and ASR9010's) and basicaly once all TCAMs are allocated, any ACE's that didn't get loaded near the end of the ACL are not being actively filtered. I've read places across the net where a single ace is 173 bytes and it's all a factor of how much memory you have available for the ACE to be placed into the ASA; however, with my past issues with the routers, I find it hard to believe you can have 300k ACE's that would consume only 512MB of RAM. Even if it took them in memory, the CPU wouldn't be able to use that list for filtering in a timely manner.
There has to be a formula especially when you want to harden your firewall with a hefty ACL blocking country IP space or just allowing your country to talk inwards.
What is SecureX?
Cisco SecureX is included with all Secure Endpoint (formerly AMP for Endpoints) subscriptions. SecureX is a cloud-native platform that aggregates capabilities across your security environment. It’s designed to simplify your environment, ...
Cisco ISE Secure Wired Access Prescriptive Deployment Guide
Authors: Hariprasad Holla (until June 2018), Mahesh Nagireddy (until Dec 2018)
For an offline or printed copy of this document, simply choose ⋮ Options > Printer ...
Meet the Authors Slides- SecureX and the Evolution of Security Orchestration Automation and Response
(Live event – Wednesday, 20th, 2021 at 10:00 a.m. Pacific / 1:00 p.m. Eastern / 6:00 p.m. Paris)
This event had place on Wednesday 20th, January 202...
The following guide goes over the in and out of the Cisco Endpoints Security Analytics Dashboard as an overview and faq page
For more information on the product offering, licensing, support, and how to solution (TAC) guide links and more please visit the...
Join us live on Tuesday, January 19 at 10:00 am PT (and on demand after) as we discuss the latest version of ATT&CK and the expansion of TTPs in v8.
As a security expert, you are tasked with protecting your environment. You see the value of...