unthredera1n is an untethered jailbreak for iPod touch (3rd generation), iPhone 3GS and A4 devices except Apple TV (2nd generation) running iOS 4.3.4 - 4.3.5 and 5.0 - 5.1.1. It is currently available for Linux (x86_64) and macOS. Not much is currently known about this tool.
unthredeh4il is an improved version of unthredera1n for iPod touch (3rd generation), iPhone 3GS and A4 devices including Apple TV (2nd generation) running iOS 4.2.6, 4.2.7, 4.2.8, 4.2.9, 4.2.10, 4.3, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 5.0, 5.0.1, 5.1 and 5.1.1 including Apple TV OS versions: 4.2, 4.2.1, 4.3 (all versions), 4.4, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 5.0, and 5.0.1. This is still an untethered jailbreak.
On Reddit, where planetbeing and saurik discussed unthredera1n, saurik said:
The program is custom; it is using the Rocky Racoon packet filter kernel exploit, but the evasi0n amfid bypass. I verified this somewhat by glancing at the binary (opens /dev/pf, etc.), but they also say this explicitly in some strings inside of the binary (which might be output when it runs or something) and in a hidden readme file. From .REAL_USAGE:
Thanks to @Chronic-Dev/@planetbeing/@posixninja for the original rocky-raccon pf kernel exploit. Thanks to @evad3rs for their awesome MobileBackup2 stuff. It worked really well on this.
From jb binary:
WE R NOT #FAKR, UNTHREADEDJB IS REEL tanks 2 @planetbeing n @posixninja n @chronicdev for #explot code in rkcy raccon :) :) :) krnl patchs from #opensn0w ))