Before diving into the tool itself, let’s break down the terminology.
It seems you're asking for a of a tool used to create an SSH ramdisk for the iPhone 4 .
Developed by the iPhone Dev Team. While primarily a jailbreak tool, its "Just Boot" option would upload a tethered ramdisk. For SSH, you had to manually build a custom bundle. Status: Deprecated, but the source logic lives on.
Currently maintained by LukeZGD , this is the most user-friendly modern tool. It auto-detects the iPhone 4, downloads the correct iOS 6.0 or 7.1.2 ramdisk components, and boots an SSH ramdisk with a single command.