TweetFollow Us on Twitter

MacEnterprise: Migrating FileVault

Volume Number: 24
Issue Number: 10
Column Tag: MacEnterprise

MacEnterprise: Migrating FileVault

Moving FileVault-encrypted accounts to a new machine

By Greg Neagle, MacEnterprise.org

Another FileVault challenge

A few issues ago, we looked at implementing FileVault in an enterprise environment. FileVault is Apple's technology for securing the contents of a user's home directory. Your organization may wish to protect its users' data on company laptops, in case a laptop is lost or stolen. Using FileVault is one method to accomplish this goal.

In those earlier issues of MacTech, we looked at preparing for FileVault implementation, turning it on for a given user account, and options for managing, automating, and controlling the use of FileVault in your organization. Later, we looked at dealing with some of the day-to-day issues in dealing with FileVault-protected home directories, and methods for recovering from a lost FileVault password.

Moving FileVault Accounts

One thing not covered in the earlier articles is how you might move a FileVault-protected account and home directory from one machine to another. If you are giving a user a new machine, you may need to move his or her existing account and home directory to the new machine. For reasons best known to Apple, the Migration Assistant is of little help in this task - it refuses to migrate a FileVault user unless there are no other users on the target machine. If you have a machine built from a standard image, you may have one or more prebuilt user accounts, like a local administrative account, on the new machine and so the Migration Assistant refuses to move the FileVault-protected user account.

The advice given by the Migration Assistant is to turn off FileVault, move the account, and turn it back on. While this might work, it is problematic for several reasons:

You'll need the user's password, or at least their cooperation, to turn FileVault off. This requires more coordination between you and the user.

You'll need enough available space on the startup disk to make a duplicate of the contents of the user's FileVault-protected home folder. That space may not be available.

Decrypting and re-encrypting the FileVault-protected home directory can take a long time.

If you are using MCX to enforce FileVault, turning it off (and back on) can present a challenge, as the GUI options are disabled.

So it would be better if we could just move the FileVault-protected account as-is. Fortunately, it can be done, and really isn't that difficult - at least if you aren't afraid of the command line.

Basic Concepts

The basic ideas behind moving the FileVault account are simple:

Recreate the account information on the new machine.

Move the FileVault sparseimage or sparsebundle to the new machine.

Edit the account information to point to the FileVault disk image.

Of course, the devil is in the details. So let's get started!

Recreating the account

If you are using mobile accounts, recreating the account is easy. Just create a new mobile account for the user - either graphically, or via the command line. In Tiger, the relevant command-line tool is MCXCacher, located in

/System/Library/CoreServices/mcxd.app/Contents/Resources/

You call it like so:

cd /System/Library/CoreServices/mcxd.app/Contents/Resources
./MCXCacher -U usershortname

which should create a new mobile account for the network user.

For Leopard, the relevant tool is called createmobileaccount. It is located in /System/Library/CoreServices/ManagedClient.app/Contents/Resources.

It's called like this:

cd /System/Library/CoreServices/ManagedClient.app
cd Contents/Resources
./createmobileaccount -n usershortname

If you aren't using mobile accounts, you can manually recreate the account using the Accounts preferences pane, or the dscl command-line utility, but be sure the shortname, uid, and GeneratedUID of the recreated account match the original. The dscl utility can be of great help here, allowing you to read the appropriate values from the old account and write them to the new one:

oldmac:/ root# dscl . read /Users/localuser uid
dsAttrTypeNative:uid: 4389
newmac:/ root# dscl . create /Users/localuser uid 4389

Another challenge, if you are not using mobile accounts, is copying the stored password from the old account and machine to the new one, but this, too, can be done. The passwords are stored in /private/var/db/shadow/hash. For local accounts, the shadow files are named after the GeneratedUID of the user account:

root# dscl . read /Users/localuser GeneratedUID
GeneratedUID: 1DECD42B-52EB-4B89-B2B2-359F0623EB1F

So for "localuser" above, the password is stored in /private/var/db/shadow/hash/1DECD42B-52EB-4B89-B2B2-359F0623EB1F. To copy the password hash from the old machine to the new one, you'd just copy that file.

Move the FileVault disk image

The next step is easier. All you need to do is copy the FileVault disk image from the old machine to the new one. But first, let's do some prep work. If you recreated the account on the new machine, you may have a folder in /Users that is partially populated. We don't really need the contents of this folder, as we're going to replace it with the FileVault disk image. If your new machine is running Tiger, or you've recreated a purely local user, just remove all the contents:

newmac:/ root# rm -rf /Users/localuser/*

If your new machine is running Leopard, and you have recreated a mobile account, you should keep the .account directory inside the user's home folder. This stores cached account info and is used by the new External Accounts in Leopard.

newmachine:/ root# ls /Users/mobileuser
.CFUserTextEncoding   Movies
.account                     Music
Desktop                     Pictures
Documents                  Public
Downloads                  Sites
Library

You can remove everything else in the user's folder; just leave .account.

Let's look at the old machine for a second. You might see two relevant directories in /Users:

.localuser/
localuser/

If you look inside .localuser/, you'll see the sparseimage/sparsebundle. If you look in localuser/, you'll see an .autodiskmounted file. This happens when the FileVault disk image is not unmounted cleanly. The important bit is that you want to find and copy the sparseimage/sparsebundle, even if it's in a different directory than you were expecting.

One strategy to copy the FileVault disk image is to startup the old machine in FireWire target disk mode, connect it to the new machine, and use sudo cp or ditto to copy the sparseimage/sparsebundle. If you do this, it's probably a good idea to uncheck the "Ignore ownership" box in the Get Info window for the FireWire-connected volume. If you don't do this, you can manually reassign ownership of the FileVault image after the copy.

cp -pvr /Volumes/oldmac/Users/myuser/myuser.sparsebundle \ /Users/myuser/myuser.sparsebundle
chown -R myuser /Users/myuser/myuser.sparsebundle

If you cannot abide the command line, it is possible to do this completely from the Finder, but you'll need to first change the permissions and/or ownership of the various directories so you can read and write. Be sure to change ownership and permissions back when you are done copying.

When you are done copying, you should have a username.sparsebundle or username.sparseimage in /Users/username on the new machine. /Users/username and /Users/username/username.sparsebundle should be owned by username, and the owner should have read, write and execute permissions:

chown -R username /Users/username
chmod -R u+rwX  /Users/username

Editing the new account

We're almost there! We've recreated the account, and we've copied the FileVault disk image. But the recreated account has the wrong value for the HomeDirectory attribute. We need to fix that. While previous steps could be done without using the command line, I'm afraid that for this task you have no choice but to fire up the terminal.

newmac:/ root# dscl . read /Users/myuser HomeDirectory   
No such key: HomeDirectory

For a "normal" non-FileVault encrypted home directory, this attribute does not exist (the NFSHomeDirectory attribute does exist, but that's a different thing...) We need to create this attribute and point it to the FileVault disk image.

dscl . create /Users/myuser HomeDirectory '<home_dir><url>file://localhost/Users/myuser/myuser.sparsebundle</url></home_dir>'

The above command should be all one line. Substitute the correct username for "myuser" and in "myuser.sparsebundle". If the encrypted home directory is in the older FileVault format, substitute "sparseimage" for "sparsebundle".

If you did everything right, the user should now be able to log in on their new machine with their username and password and access their FileVault-encyrpted home directory. And maybe you've learned some things about FileVault, mobile accounts and the Directory Service along the way.

Wrapping up

To review:

We recreated the user account on the new machine, using MCXCacher or createmobileaccount if the account was a mobile account; or manually if it was a local account, ensuring the shortname, uid, and GeneratedUIDs matched.

For local accounts, we copied the shadow password file. (Recreating a mobile account generates this for us automatically)

We copied the FileVault disk image from the old machine to the new one.

We edited the local accounts' HomeDirectory attribute to point to the FileVault disk image.

That was a lot of work - but should have been faster than turning FileVault off, moving the account and data, and then turning it back on. Additionally, the user's password was not needed to move the account and data. Once you get this technique down, you might consider writing a script to do most of it for you, which is, of course, what I've done. Better would be to help persuade Apple to update the Migration Assistant to do this: if we can do it, so could the Migration Assistant!


Greg Neagle is a member of the steering committee of the Mac OS X Enterprise Project (macenterprise.org) and is a senior systems engineer at a large animation studio. Greg has been working with the Mac since 1984, and with OS X since its release. He can be reached at gregneagle@mac.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
VOX 2.5.1 - Music player that supports m...
VOX is a beautiful music player that supports many filetypes. The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all... Read more
NetNewsWire 4.0.0 - RSS and Atom news re...
NetNewsWire is the best way to keep up with the sites and authors you read most regularly. Let NetNewsWire pull down the latest articles, and read them in a distraction-free and Mac-like way. Native... Read more
MacUpdate Desktop 6.0.6 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
ForkLift 2.6.5 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Drive Genius 4.1.0 - Powerful system uti...
Drive Genius 4 gives you faster performance from your Mac while also protecting it. The award-winning and improved DrivePulse feature alerts you to hard drive issues before they become major problems... Read more
OnyX 2.9.7 - Maintenance and optimizatio...
OnyX is a multifunctional utility for OS X. It allows you to verify the startup disk and the structure of its System files, to run miscellaneous tasks of system maintenance, to configure the hidden... Read more
DEVONthink Pro 2.8.5 - Knowledge base, i...
DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research papers, your life often fills your hard drive in the... Read more
Backblaze 4.0.1.878 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more

Auroch Digital is Bringing Back Games Wo...
| Read more »
Carbo - Handwriting in the Digital Age...
Carbo - Handwriting in the Digital Age 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Draggy Dead (Games)
Draggy Dead 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Ditch your dead end job and take up a rewarding career in Grave Robbing today!Guide the recently deceased to a fun filled life of... | Read more »
Bad Dinos (Games)
Bad Dinos 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Apple Watch isn't Great as a Fi...
| Read more »
Show the World What You See With Stre.am...
Live broadcasting is getting popular on mobile devices, which is why you can now get Stre.am, by Infinite Takes. [Read more] | Read more »
PhotoTime's 2.1 Update Adds Apple W...
The latest PhotoTime update is adding even more functionality to the handy photo organizing app. Yep, including Apple Watch support. [Read more] | Read more »
Oh My Glob! Adventure Time Puzzle Quest...
Finn and Jake are taking over D3 Go!'s popular puzzle game series in the upcoming Adventure Time Puzzle Quest. [Read more] | Read more »
Earthcore: Shattered Elements - Tips, Tr...
At first glance, Earthcore: Shattered Elements seems like a rather simple card-battling game. Once you’re introduced to skills that will change quite a bit. Even more so once you start to acquire hero cards. But it’s not so complicated that we... | Read more »
Dungeon999F (Games)
Dungeon999F 1.33 Device: iOS Universal Category: Games Price: $.99, Version: 1.33 (iTunes) Description: "The game you must play at least once in your life!" "The game with potential of million downloads globally!" ...is what the... | Read more »

Price Scanner via MacPrices.net

OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more
Price drop on 2014 15-inch Retina MacBook Pro...
B&H Photo has dropped prices on 2014 15″ Retina MacBook Pros by $200. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 save $200 - 15″ 2.5GHz... Read more
With a Mission to Make Mobile Free, Scratch W...
Scratch Wireless, claiming to be the world’s first truly free mobile service, has announced the availability of a new Scratch-enabled Android smartphone, the Coolpad Arise. The smartphone is equipped... Read more
First-Ever Titanium Alloy Curved iPhone 6 Scr...
One of the most common problems with mobile phones is damage to the screens. The slightest drop can cause a dreaded spider web of gashes and cracks in the glass panel surface that can cost $hundreds... Read more
Preorder new 12-inch MacBook, $10 off, save o...
Adorama has new 12″ Retina MacBooks available for preorder for $10 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB... Read more
Will iOS 9 Finally Bring Productivity Friendl...
Ah, the irony. From its original announcement in 2010, Apple has doggedly insisted that the iPad remain “simple,” thus arbitrarily limiting its considerable potential as a content creation and... Read more

Jobs Board

Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
Visual Merchandise Manager %u2013 Accessories...
…to be part of an incredible team. Imagine what you could do here. At Apple , great ideas have a way of becoming reality very quickly. Our Accessories assortment makes Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** The ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store which delivers Read more
Technical Project Manager - *Apple* Pay - A...
**Job Summary** Apple Pay is seeking an experienced technical PM…manage the rollout of features to merchants for the Apple Pay platform in the US Within this role Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.