Avoid downloading IOS images from third-party "warez" sites. These images are copyrighted Cisco property and modified images can contain malware or unstable bugs.
If you own a physical Catalyst 4500, you can copy the IOS image from its flash memory to a TFTP server. However, as mentioned, these hardware-specific images usually won't boot in GNS3’s Dynamips environment. Better Alternatives for GNS3 Switching cisco 4500 switch ios download for gns3
or similar software. Consequently, there is no official or functional IOS image for the Catalyst 4500 that can be downloaded and run as a standalone switch in GNS3. Recommended Alternatives Avoid downloading IOS images from third-party "warez" sites