Most users upload this file to /opt/unetlab/addons/iol/bin/ . After fixing permissions, it becomes a selectable node in the lab interface.

It is important to note that They were originally created for Cisco engineers to test features without needing hardware. To use them legally in a lab, you typically need an iourc license file, which contains a license key mapped to the hostname of your Linux lab server.

You won't find this file on a standard Cisco router. Instead, it is used in:

There are three main ways to run Cisco IOS virtually, but IOL (and this specific 2018 build) is often preferred for several reasons: