iOS 4.2.1 Final Version Jailbroken Using Updated Redsn0w 0.9.6b4 [How to Guide]
The iPhone Dev Team has just released Redsn0w 0.9.6b4 today which brings first proper jailbreak, with working Cydia and MobileSubstrate for all iOS 4.2.1 devices. — For those of you who don't know …
Context & Ripple Effects
This is the latest turn in a cat-and-mouse cycle the iPhone Dev Team has run since 2007, when a preliminary 1.1.1 jailbreak first showed third-party apps ported and running on the device and follow-on tools like the 1.1.2 jailbreak software kept pace with each firmware drop. The pattern repeated when iPhone OS 3.1 was jailbroken almost immediately after release in September 2009.
What is different with Redsn0w 0.9.6b4 on iOS 4.2.1 is scope: it is described as the first proper jailbreak covering all 4.2.1 devices, including the iPad, with working Cydia and MobileSubstrate rather than a partial or tethered stopgap. It also lands two months after Cydia's confirmed acquisition of rival store Rock Your Phone, meaning the jailbreak ecosystem's storefront side has just consolidated into a single dominant player.
First-order effects
- Owners of every iOS 4.2.1 device can now install Cydia and MobileSubstrate extensions, giving tweak developers an immediate audience across iPhone, iPod touch and iPad rather than a fragmented per-device toolset.
- The Dev Team's release resets its standing as the de facto gatekeeper of the jailbreak scene, with Redsn0w becoming the standard entry point for non-developers.
Second-order effects
- Apple now faces pressure to patch whatever exploit chain Redsn0w 0.9.6b4 relies on in its next firmware update, continuing the fix-and-rebreak rhythm it has run against the Dev Team since 2007.
- With Rock.app absorbed into Cydia as of the September acquisition, tweak developers have one storefront to target, concentrating distribution and pricing power around Cydia instead of splitting it across competing stores.
Third-order effects
- If each major firmware release keeps getting jailbroken on or near launch day, jailbreaking functions less as a hack than as a parallel platform layered on iOS — one Apple tolerates only through reactive patching rather than structural prevention.
- A consolidated Cydia atop a reliable cross-device jailbreak points toward the unofficial ecosystem maturing into a stable secondary market, raising the stakes for any future legal or technical attempt by Apple to shut it down.
The trend: Every iOS firmware release since 2007 has been met by a Dev Team counter-release within weeks, making jailbreaking a recurring arms race that Apple manages rather than ends.