Each time you allow iTunes to update your iOS device, iTunes will automatically delete the previous iOS firmware (ipsw) file from your computer. As a result you will not be able to restore your iOS device to one of these older iOS firmware. I decided to create a place where I list all the iOS firmware Apple ever released in the past. The following are all hyperlinks to Apple's official repositories, so there are no worries if any of these package contains malware payloads.

iPhone links:

iPad links:

iPod touch links:

I will do my best to update this list as Apple releases new iOS firmwares. I do not know how long Apple will continue to offer access to these files, I would be happy to serve these files from my own repository, but worry about infringing on Apple's copyrights.

If I have missed any, please feel free to share the official Apple hyperlinks to iOS firmware versions in the form of comments below.