This is probably the most complete collection of Cisco IOS you find on the internet.
I have been digging through many servers.
The biggest amount was actually found as link on archive.org to a lone little server. Many images
present but downloading was a pain.
The rest did sum up by strolling through ftp servers of universities all over the world.
Again a BIG torrent. As usual with more than standard recovery data to fix broken archives.
I have split the archive into series.
So 1xxx stands for all routers and switches with a model number in the range of 1000 to 1999.
There are also a few other images like for ASA (firewall), SOHO and VOIP systems.
So you are able just to download a specific archive if you need it.
To download everything and seed is of course way better ;)
I also added Packet Tracer 7.2.
You can either register at netacad.com to use Packet tracer or run it anonymously. Cancelling the
login is the way to do so if I recall right.
So if you are prepping Cisco certificates with GNS3 or want to modify the IOS on your hardware; this
should help you a great deal.
I am not sure what the latest state is. A big amount of the collection was dated to 2011 but the
other images I found may be more recent.