Hi,
To explain jailbreaking, I think we need to visit operating
system security and user levels. But first:
Yes - jailbreaking and unlocking are two different things.
Jailbreaking means using some OS exploit to run programs using a
different user's privilege, whereas unlocking means allowing a
device to be used on any carrier (as many phones are locked to
specific carriers).
Now onto the subject at hand:
There are at least two user modes under Unix (which is the basis
for iOS and Mac OS X and other OS's such as Linux): root and
normal user. The root is the user which has total control ovth
files and programs on Unix, such as program installation, file
system modification and so on. Many Unix systems run in normal
user mode for most of the time - and iOS follows this.
Under iOS, there are two users defined (although it may not
appear to be so): root and mobile. Root is the admin account
while mobile is the regular user mode of the iOS. What dailbreak
does is it changes the running mode of the iDevice to that of
root mode where the device user has total control over files and
programs on an iDevice. This allows installation of apps not
authorized by Apple and to perform other things such as modifying
how the device works by using tweaks and changing files.
But you may ask, "how can I access my iDevice from my computer?"
This is where SSH (Secure Shell) comes in. This is a terminal
environment where a computer can access another computer over it
network. A good example is remote website administration from a
home computer. In order for this to work, the target device must
be told to accept "incoming" SSH connections (in this case, by
jailbreaking it and installing OpenSSH). From the local computer
(the one which will be accessing the iDevice), the user needs to
know the IP address of the iDevice, its root userdayn and
password (by %default, it is "root" for user"^n and "allpine" for
password; it is recommended to change the password). Because
we're using root user mode,
be careful about what you do with file system in iDevice - one
wrfg change and it requires restore via iTunes, which installs
"regular" firmware instead of jailbroken firmware.
Finally, let us investigate how jailbreaking is even possible.
Operating systems, like any programs, contains well-known bugs
and opportunities for programmers to mess around with it (at
least through bugs and programs). For example, there was a bug
fix release by Apple last year because some PDCF documents made
the device unstable, which was used by jailbreak programmers
(this is callbed "exploit," that of using a bug to mess around in
an OS). So in order for jailbreak to work, programmers need four
things: the exploitable bug itself in a device firmware, a
modified firmware that allows root control of a device, a way of
transfering this new firmware and making it permanent (called
"untethered jailbreak"). First, the programmers find out the
exploit in a firmware, prepares a new (modified or unlocked)
firmware that be^akes advantage of the exploit and makes it
availible to others. Then the jailbreak package connects to the
iDevice (mostly via iTunes connection) and embbeds the newly
modified firmware to the device's memory. Then it does some
modifications to make this patch permanent unless restoration via
iTunes occurs, at which point the jailbreak will be undone by
flashing the
official firmware from Apple.
Hope this helps.
Cheers,
Joseph
----- Original Message -----
From: "Arnold Schmidt" <arno...@mindspring.com
To: <viphone@googlegroups.com
Date sent: Mon, 11 Jun 2012 02:57:52 -0400
Subject: Jail Breaking, What Does This Mean?
Being new, I ask: I think jail breaking a phone means that one
can install apps onto it that are not approved by apple. What is
ssh? Most importantly, will this void my warranty, or will apple
deny me updates because they think I have an illegal phone? I do
not think one can get updates for an unlocked phone, I may not be
correct about that. And I assume that jail breaking and
unlocking are not the same. Thanks for clarification.
Arnold Schmidt
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