Cisco recommends that customers still using ACS migrate to the Cisco Identity Services Engine (ISE) , which is the current platform for secure network access control. where to get acs 5.5 recovery iso - Cisco Community

Cisco Access Control System (ACS) has reached the end of its life. Specifically, Cisco ACS 5.5 reached several years ago. This has major implications for anyone looking for the ISO:

Cisco Secure Access Control System (ACS) 5.5 reached its , and is now considered obsolete. Official ISO downloads for version 5.5 are no longer available from the Cisco Software Download portal. Important Status & Lifecycle Details

The final day to receive assistance from the Cisco Technical Assistance Center (TAC) for ACS 5.5 was April 30, 2018 .

ACS 5.5’s kernel lacks drivers for SAS controllers on modern servers. Use VMware virtual disks (LSI Logic SAS) rather than physical pass-through.