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.

 
AAPL
$102.08
Apple Inc.
+2.32
MSFT
$44.83
Microsoft Corpora
+0.75
GOOG
$523.95
Google Inc.
+3.11

MacTech Search:
Community Search:

Software Updates via MacUpdate

RapidWeaver 6.0 - Create template-based...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
NTFS 12.0.39 - Provides full read and wr...
Paragon NTFS breaks down the barriers between Windows and OS X. Paragon NTFS effectively solves the communication problems between the Mac system and NTFS, providing full read and write access to... Read more
RestoreMeNot 2.0.3 - Disable window rest...
RestoreMeNot provides a simple way to disable the window restoration for individual applications so that you can fine-tune this behavior to suit your needs. Please note that RestoreMeNot is designed... Read more
Macgo Blu-ray Player 2.10.9.1750 - Blu-r...
Macgo Mac Blu-ray Player can bring you the most unforgettable Blu-ray experience on your Mac. Overview Macgo Mac Blu-ray Player can satisfy just about every need you could possibly have in a Blu-ray... Read more
Apple iOS 8.1 - The latest version of Ap...
The latest version of iOS can be downloaded through iTunes. Apple iOS 8 comes with big updates to apps you use every day, like Messages and Photos. A whole new way to share content with your family.... Read more
TechTool Pro 7.0.5 - Hard drive and syst...
TechTool Pro is now 7, and this is the most advanced version of the acclaimed Macintosh troubleshooting utility created in its 20-year history. Micromat has redeveloped TechTool Pro 7 to be fully 64... Read more
PDFKey Pro 4.0.2 - Edit and print passwo...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Yasu 2.9.1 - System maintenance app; per...
Yasu was originally created with System Administrators who service large groups of workstations in mind, Yasu (Yet Another System Utility) was made to do a specific group of maintenance tasks... Read more
Hazel 3.3 - Create rules for organizing...
Hazel is your personal housekeeper, organizing and cleaning folders based on rules you define. Hazel can also manage your trash and uninstall your applications. Organize your files using a... Read more
Autopano Giga 3.7 - Stitch multiple imag...
Autopano Giga allows you to stitch 2, 20, or 2,000 images. Version 3.0 integrates impressive new features that will definitely make you adopt Autopano Pro or Autopano Giga: Choose between 9... Read more

Latest Forum Discussions

See All

Tilt to Live: Gauntlet’s Revenge is Almo...
Tilt to Live: Gauntlet’s Revenge is Almost Here Posted by Jessica Fisher on October 21st, 2014 [ permalink ] One Man Left has announced the official release date of Tilt to Live: Gauntlet’s Re | Read more »
Sago Mini Monsters Celebrates Halloween...
Sago Mini Monsters Celebrates Halloween with Fun Costumes and Special Treats. Posted by Jessica Fisher on October 21st, 2014 [ permal | Read more »
Inferno 2 Review
Inferno 2 Review By Andrew Fisher on October 21st, 2014 Our Rating: :: TWIN STICK GOODNESSUniversal App - Designed for iPhone and iPad With tight controls and awesome, stark visuals, Inferno 2 is loads of fun.   | Read more »
Clips Review
Clips Review By Jennifer Allen on October 21st, 2014 Our Rating: :: CONVENIENT PASTINGUniversal App - Designed for iPhone and iPad Making copying and pasting more powerful than usual, Clips is a great way to move stuff around.   | Read more »
MonSense Review
MonSense Review By Jennifer Allen on October 21st, 2014 Our Rating: :: ORGANIZED FINANCESiPhone App - Designed for the iPhone, compatible with the iPad Organize your finances with the quick and easy to use, MonSense.   | Read more »
This Week at 148Apps: October 13-17, 201...
Expert App Reviewers   So little time and so very many apps. What’s a poor iPhone/iPad lover to do? Fortunately, 148Apps is here to give you the rundown on the latest and greatest releases. And we even have a tremendous back catalog of reviews; just... | Read more »
Angry Birds Transformers Review
Angry Birds Transformers Review By Jennifer Allen on October 20th, 2014 Our Rating: :: TRANSFORMED BIRDSUniversal App - Designed for iPhone and iPad Transformed in a way you wouldn’t expect, Angry Birds Transformers is a quite... | Read more »
GAMEVIL Announces the Upcoming Launch of...
GAMEVIL Announces the Upcoming Launch of Mark of the Dragon Posted by Jessica Fisher on October 20th, 2014 [ permalink ] Mark of the Dragon, by GAMEVIL, put | Read more »
Interview With the Angry Birds Transform...
Angry Birds Transformers recently transformed and rolled out worldwide. This run-and-gun title is a hit with young Transformers fans, but the ample references to classic Transformers fandom has also earned it a place in the hearts of long-time... | Read more »
Hail to the King: Deathbat Review
Hail to the King: Deathbat Review By Rob Thomas on October 20th, 2014 Our Rating: :: SO FAR AWAYUniversal App - Designed for iPhone and iPad Hail to the King: Deathbat may feel like “Coming Home” for Avenged Sevenfold’s faithful,... | Read more »

Price Scanner via MacPrices.net

Select MacBook Airs $100 off MSRP, free shipp...
B&H Photo has 2014 a couple of MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels Desktop and LoJack for... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999.99 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more
Strong iPhone, Mac And App Store Sales Drive...
Apple on Monday announced financial results for its fiscal 2014 fourth quarter ended September 27, 2014. The Company posted quarterly revenue of $42.1 billion and quarterly net profit of $8.5 billion... Read more
Apple Posts How-To For OS X Recovery
OS X 10.7 Lion and later include OS X Recovery. This feature includes all of the tools you need to reinstall OS X, repair your disk, and even restore from a Time Machine backup. OS X Recovery... Read more
Mac OS X Versions (Builds) Supported By Vario...
Apple Support has posted a handy resource explaining which Mac OS X versions (builds) originally shipped with or are available for your computer via retail discs, downloads, or Software Update. Apple... Read more
Deals on 2011 13-inch MacBook Airs, from $649
Daily Steals has the Mid-2011 13″ 1.7GHz i5 MacBook Air (4GB/128GB) available for $699 with a 90 day warranty. The Mid-2011 13″ 1.7GHz i5 MacBook Air (4GB/128GB SSD) is available for $649 at Other... Read more
2013 15-inch 2.0GHz Retina MacBook Pro availa...
B&H Photo has leftover previous-generation 15″ 2.0GHz Retina MacBook Pros now available for $1599 including free shipping plus NY sales tax only. Their price is $400 off original MSRP. B&H... Read more
Updated iPad Prices
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers, including the new iPad Air 2 and the... Read more
Apple Pay Available to Millions of Visa Cardh...
Visa Inc. brings secure, convenient payments to iPad Air 2 and iPad mini 3as well as iPhone 6 and 6 Plus. Starting October 20th, eligible Visa cardholders in the U.S. will be able to use Apple Pay,... Read more
Textkraft Pocket – the missing TextEdit for i...
infovole GmbH has announced the release and immediate availability of Textkraft Pocket 1.0, a professional text editor and note taking app for Apple’s iPhone. In March 2014 rumors were all about... Read more

Jobs Board

Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
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
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.