In order run Cisco IOS image in GNS3, first we need to download the images. Download Cisco IOS (Dynamips images) GNS3 If you want to practice Cisco ASA / IOU/ IOL on eve-ng for your certification or knowledge then check below posts.
We will explain you step by step process of How to add Cisco IOS (Dyanamips Images) to GNS3. In GNS3 you can import Cisco IOS Router images and practice as much as you want. GNS3 is one of the renown and best network software simulator released in 2008.