Understanding untethered, semi-untethered, semi-tethered, and tethered jailbreaks

jailbreak types

If you’ve been poking around in the jailbreak community for as long as I have, then you’ve undoubtedly witnessed a plethora of different jailbreak types. Among the most popular in this community are untethered, semi-untethered, semi-tethered, and tethered, each of which exhibit different attributes that every jailbreaker should be aware of.

We understand that some are new to jailbreaking, but even those who’ve been around as long as I have might have some confusion between the different types. For this reason, we’ve compiled a quick guide to help everyone understand what each of these different jailbreaks are and how they behave.

Tethered Jailbreak

A tethered jailbreak is one that temporarily pwns a handset for a single boot. After the device is turned off (or the battery dies), it can’t complete a boot cycle without the help of a computer-based jailbreak application and a physical cable connection between the device and the computer in question.

Tethered jailbreaks are perhaps the most troublesome at all for end users because a dead battery can be unavoidable and this turns off your device. Should you attempt to power cycle a tethered device without a computer handy, you would be unable to turn it back on again fully to make a phone call or send a text message, and this can spell out trouble for daily-driver handsets when the user finds themselves in an emergency.

Upon attempting to power a tethered device back on, you would need to connect it to a computer with a supported USB cable, enter DFU mode, and re-run the jailbreak tool you used previously. Only then could you get back to your Home screen to use your device as you normally would. Without doing this, you’d experience what many refer to as a ‘recovery loop’ or ‘boot loop,’ and the device wouldn’t stop doing this until booted with the proper jailbreak tool.

Perhaps the greatest example of a tethered jailbreak was redsn0w, a (now ancient) application for macOS and Windows that could jailbreak A4-equipped devices such as the infamous iPhone 4.

Semi-Tethered Jailbreak

A semi-tethered jailbreak is one that permits a handset to complete a boot cycle after being pwned, but jailbreak extensions won’t load until a computer-based jailbreak application is deployed over a physical cable connection between the device and the computer in question.

Semi-tethered jailbreaks aren’t as troublesome as tethered jailbreaks because you can power cycle your device and expect to use it normally thereafter, such as making phone calls and sending text messages. On the other hand, jailbreak tweaks won’t initialize on the freshly-booted device and jailbreak-based apps such as Cydia and Filza will simply crash on launch them until the device is booted back into a jailbroken state.

Just as the name implies, a semi-‘tethered’ jailbreak necessitates a physical cable connection between the device and the computer when running the jailbreak tool to patch the kernel and reinitialize the jailbroken state, but the good thing here is that you can still access critical core smartphone functionality in a pinch when you don’t have a computer nearby.

The brand-new checkra1n jailbreak tool for macOS (and soon Windows) is a prime example of a semi-tethered jailbreak, and can pwn A7-A11-equipped devices as old as the iPhone 5s and as new as the iPhone X.

Semi-Untethered Jailbreak

A semi-untethered jailbreak is one that permits a handset to complete a boot cycle after being pwned, but jailbreak extensions won’t load until a side-loaded jailbreak app on the device itself is deployed.

Semi-untethered jailbreaks are fairly easy to cope with on daily-driver handsets because you don’t need a computer whatsoever to use them. A semi-untethered jailbreak app can be side-loaded over a physical cable connection from a computer via the Cydia Impactor program or downloaded directly on the device itself with a signing service like Ignition.

Upon putting the jailbreak app on your Home screen, you need only tap the ‘Jailbreak’ button in the app after each power cycle to reinitialize the jailbroken state with full access to your jailbreak tweaks and extensions. Depending how you go about it, this jailbreak can be ‘computerless,’ but it unfortunately doesn’t sustain itself after a reboot.

Two great examples of a semi-untethered jailbreak are Chimera and unc0ver, which are apps that can be side-loaded or installed over the air to jailbreak a plethora of devices on various firmware versions.

Untethered Jailbreak

An untethered jailbreak is one that permits a handset to complete a boot cycle after being pwned without any interruption to jailbreak-oriented functionality.

Untethered jailbreaks are the most sought-after of all, but they’re also the most challenging to achieve because of the powerful exploits and developmental skill they require. An untethered jailbreak can be dispatched over a physical USB cable connection to a computer or directly on the device itself by way of an application-based exploit, such as a website in Safari.

Upon running an untethered jailbreak, you can turn your pwned handset off and on again without running the jailbreak tool again. All your jailbreak tweaks and apps would then continue operating without any user intervention necessary.

It’s been a long time since iOS has gotten the untethered jailbreak treatment. The most recent example was the computer-based Pangu jailbreak, which supported most handsets that ran iOS 9.1. We’ve also witnessed an untethered jailbreak in the form of JailbreakMe, which allowed users to pwn their handsets directly from the mobile Safari web browser without a computer.

Wrapping Up

Don’t be afraid to try different jailbreak types just because they aren’t fully untethered. The only jailbreak that we wouldn’t recommend for a daily driver device is the tethered fashion, as it can quite literally render your device useless if the battery dies or you power it off until you can access a computer. All the other jailbreak types allow you to at least use your smartphone’s core functionality, which can spell out life or death in an emergency situation.

Which types of jailbreaks have you used before? Do you have a preference on which ones you’ll use and which ones you won’t? Share in the comments section.