iPod ipsw firmware download that provided by Apple, when you do the relevant operation at your own risk.
19H422 · iPod9,1
16H88 · iPod7,1
13G36 · iPod5,1
12H321 · iPod5,1
10B500 · iPod4,1
9B206 · iPod3,1
8B117 · iPod3,1
8C148 · iPod2,1
8B117 · iPod2,1