, use checkra1n for supported devices (iPhone 5s–X) or ipwndfu for iPhone 3G/3GS. Forget the blackra1n name – it's historical.

: For newer devices at the time (like the 3rd Gen iPod Touch), it was a "tethered" jailbreak, requiring the tool to be rerun if the battery died or the device restarted. Running blackra1n on Linux