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Tiny Deathstars of Foulness

Clients discover the Apple Caching service bundled with macOS Server (and in the future macOS) automatically. You can create a text recored for _aaplcache._tcp on your DNS server. That would look

_aaplcache._tcp 518400 IN TXT “prs=192.168.50.100”

Name: _aaplcache._tcp with a type of TXT and a TTL of 518400 seconds. The prs is the address to be used and is set to a value using prs=192.168.50.100.

June 15th, 2017

Posted In: Mac OS X Server

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Some apps have defaults domains that don’t work the same as other apps and you need to use the -app option in defaults. This option is available for most apps, and sometimes I’ll use it to specifically crawl around for a specific setting I’m looking for. But for other apps, you need to interact with them there. So let’s look at Eclipse. Here, we can do a read with -app followed by the path:

defaults read -app /Applications/eclipse/Eclipse.app/

The output would be as follows:

{
NSNavLastRootDirectory = “~/smb/smb”;
NSNavPanelExpandedSizeForOpenMode = “{712, 426}”;
NSScrollAnimationEnabled = 0;
WebKitJavaEnabled = 0;
}

Now, let’s say you had a specific setting, like fixing an anti-aliasing issue:

defaults write -app /Applications/eclipse/Eclipse.app AppleAntiAliasingThreshold 19

#thanksaloteclipseupdaters

June 4th, 2017

Posted In: Java, Mac OS X, Mac OS X Server, Mac Security

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June 2nd, 2017

Posted In: Mac OS X, Mac OS X Server, Mac Security, MacAdmins Podcast

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Added 3 new flags into precache tonight: –jamfserver, –jamfuser, and –jamfpassword. These are used to provide a Jamf Pro server (or cloud instance), the username to an account that can list the mobile devices on that server, and a password to that account respectively.

Basically, when you provide these, the script will pull a unique set of models and then precache updates for them. It’s similar to grabbing a list of devices:

curl -s -u myuser:mypassword https://myserver.jamfcloud.com/JSSResource/mobiledevices

And then piping the output of a device list to:

perl -lne 'BEGIN{undef $/} while (/<model_identifier>(.*?)<\/model_identifier>/sg){print $1}'

And then running that array as an input to precache.py. Hope this helps make the script more useful!

May 13th, 2017

Posted In: iPhone, Mac OS X Server

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If you’re in need of MDM in Japanese or German, Jamf Now shipped support for those languages last week. To switch languages, click on your name once logged in, and then click on the language you would like to use.

Enjoy.

May 1st, 2017

Posted In: iPhone, Mac OS X, Mac OS X Server, Mac Security, Mass Deployment

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I mentioned mdmclient when I gave the talk on the inner workings of Mobile Device Management, or MDM. There, I spent a lot of time on APNs and profiles, but just kinda’ spoke about mdmclient in terms of it being the agent that runs on macOS to provide mdm parity for the Mac. The mdmclient binary is located at /usr/libexec/mdmclient and provides pretty limited access to see how the Mac reacts to and interprets information coming from a device management provider.

I had been meaning to do a write-up on mdmclient and document what it can do since it first shipped. But as luck would have it, @Mosen on the Slacks beat me to the punch with a fantastic resource at https://mosen.github.io/profiledocs/troubleshooting/mdmclient.html. So here I’d like to focus on just 3 examples of using mdmclient. The first is to see what insight an MDM has to the applications installed (whether that information is actually committed to a database somewhere or not) using QueryInstalledApps:

/usr/libexec/mdmclient QueryInstalledApps

Here, we can see an array output of each bundle installed:

{BundleSize = 27457223;
Identifier = “com.hipchat.HipChat”;
Name = HipChat;
ShortVersion = “3.1.6”;
Version = “3.1.6”;}

Now, we can end up with duplicates, and so focus on just the unique Identifier keys, as follows:

/usr/libexec/mdmclient QueryInstalledApps | grep Identifier | uniq

The second iteration is to see installed profiles. The most basic of these, is to see user profiles, which can be obtained using QueryInstalledProfiles, as follows:

/usr/libexec/mdmclient QueryInstalledProfiles

Now, I could see using the profiles command with the -L option that I have a profile to configure office365 on my machine:

profiles -L

charlesedge[1] attribute: profileIdentifier: com.jamfsw.office365.a5f0e328-ea86-11e3-a26c-6476bab5f328
There are 1 user configuration profiles installed for ‘charlesedge’

So to see what that same information looks like, when queried from an MDM solution:
/usr/libexec/mdmclient QueryInstalledProfiles

QueryInstalledProfiles then returns:

({HasRemovalPasscode = 0;
IsEncrypted = 0;
PayloadContent = (
{PayloadDisplayName = “Charles Edge’s Office 365”;
PayloadIdentifier = “com.jamfsw.office365.a5f0e328-ea86-11e3-a26c-6476bab5f328.exchange.a5f2ccd9-ea86-11e3-b1e0-6476bab5f328”;
PayloadType = “com.apple.ews.account”;
PayloadUUID = “a5f2ccd9-ea86-11e3-b1e0-6476bab5f328”;
PayloadVersion = 1;});
PayloadDescription = “This will configure your Office 365 account for your Mac.”;
PayloadDisplayName = “Charles Edge’s Office 365”;
PayloadIdentifier = “com.jamfsw.office365.a5f0e328-ea86-11e3-a26c-6476bab5f328”;
PayloadOrganization = “JAMF Software”;
PayloadRemovalDisallowed = 0;
PayloadUUID = “a5f0e328-ea86-11e3-a26c-6476bab5f328”;
PayloadVersion = 1;
SignerCertificates = ();})

You can then take action based on this type of information, allow you to either fill a database for agent-based management, or simply take action if something is missing, etc.

QueryInstalledProfiles covers user profiles. To see system, you’ll need installedProfiles:

/usr/libexec/mdmclient installedProfiles | grep "Profile Name"

Run without the grep for a considerably more verbose amount of information.

Finally, let’s look at one more piece of information, which is the hash for the iTunes Store. That’s a point I’ve made a number of times, that the iTunes account email address is never provided to an MDM, once associated to a device or user on a device. Instead, there’s a hash of the account. These are important with VPP, as it allows for reversing (according to the MDM) which users have claimed which apps, or which users are using a given app, as well as how many devices they’re accessing those from. To see a hash, as an MDM sees it:

/usr/libexec/mdmclient QueryAppInstallation | grep iTunesStoreAccountHash

There’s a lot more you can do here, and I’m sure we’ll see a lot more over time. However, the work from @mosen combined with the opening up of the documentation on profiles and the mdm protocol helps to shed some light on how things work under the hood, and how we can use these features to provide greater programatic management for the Mac.

For example, to grab that iTuneshash from earlier, as a Jamf extension attribute you could use the following: https://github.com/krypted/ituneshash/blob/master/ituneshash.sh

April 28th, 2017

Posted In: Mac OS X, Mac OS X Server, Mac Security

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Here’s a new extension attribute at https://github.com/krypted/ituneshash/blob/master/ituneshash.sh for grabbing the hash ID used for iTunes Store accounts, useful with VPP:

#!/bin/sh
#
#
#
#Jamf Pro Extension Attribute to return the App Store Account Hash for iTunes
#Note that the return is null if one is not found
#
#
result=`/usr/libexec/mdmclient QueryAppInstallation | grep iTunesStoreAccountHash | sed '/.*\"\(.*\)\".*/ s//\1/g'`
echo "<result>$result</result>"

The output is something like:

<result>oBSmAAAa0nUAAACBHe5AaALlNBg=</result>

Which would bring the string into Jamf Pro

April 26th, 2017

Posted In: JAMF, Mac OS X, Mac OS X Server, Mac Security

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10.12.4 gives us a new option to recheck enrollment via DEP! You can now use the -N flag to recheck a DEP configuration and, if a computer is not enrolled in the correct listing, move the enrollment. This should makes of r an ability to move devices between server, change the URL string in an enrollment profile, and recheck for the removal of an enrollment profile.

To use the option, simply run profiles with the -N option (with elevated privileges):

sudo profiles -N

For the Mac, there are a lot of ways to programmatically handle enrollment, so this is a nice new feature, but not a game changer. But, while not yet available in iOS, if the same functionality could be had with, say, a MDM command, then you would be able to migrate iOS devices between MDMs, provided you already put the data in place so policies ran as expected.

April 18th, 2017

Posted In: Mac OS X, Mac OS X Server, Mac Security

There are two useful commands when scripting operations that involve filenames and paths. The first of these is dirname: dirname can be used to return the directory portion of a path. The second is basename: basename can be used to output the file name portion of a path.

For our first example, let’s say that we have an output of /users/krypted, which we know to be the original short name of my user. To just see just that username, we could use basename to call it:

basename /users/charlesedge

Basename can also be used to trim output. For example, let’s say there was a document called myresume.pdf in my home folder and we wanted to grab that without the file extension. We could run basename using the -s option, followed by the string at the end that we do not want to see to output of (the file extension:

basename -s .pdf /users/charlesedge/myresume.pdf

The dirname command is even more basic. It outputs the directory portion of the file’s path. For example, based on the same string, the following would tell you what directory the user is in:

dirname /users/charlesedge

A great example of when this gets more useful is keying off of currently active data. For example, if we’re scripting a make operation, we can use the which command to get an output that just contains the path to the make binary:

which make

We can then wrap that for expansion and grab just the place that the active make binary is stored:

dirname `which make`

This allows us to key other operations off the path of an object. A couple of notable example of this is home or homeDirectory paths and then breaking up data coming into a script via a positional parameter (e.g. $1).

You can also use variables as well. Let’s say that

homedir=/users/krypted ; dirname $homedir

Finally, keep in mind that dirname is relative, so if you’re calling it for ~/ then you’ll see the output at that relative path.

April 5th, 2017

Posted In: Mac OS X, Mac OS X Server, Mac Security, Mass Deployment

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The xxd is a bash command in Linux and macOS that is used to take a hexdump (convert a string to hex), or convert hex back to a string. To use xxd, just call it with a couple of options. Below, we’ll use the -p option to export into plain hexdump, and we’ll quote it and the <<< is to take input rather than a file name to convert (the default behavior), as follows:

xxd -p <<< "hey it's a string"

The output would be a hex string, as follows:

6865792069742773206120737472696e670a

Then use the -r option to revert your hex back to text. Since xxd doesn’t allow for a positional parameter to revert, we’ll simply echo the hex string and pipe it back into xxd, as follows:

echo 6865792069742773206120737472696e670a | xxd -r -p

And the output would be (is):

hey it's a string

Other useful options:

  • -b: Perform a binary dump instead of a hex dump
  • -e: what it looks like when a little endian takes a hex dump
  • -h: get help with the command
  • -len: stop after the defined number of characters
  • -u: use uppercase in the hex, instead of the default lower-case (doesn’t seem to actually work on macOS)
  • -v: grab the version of xxd

April 2nd, 2017

Posted In: Mac OS X, Mac OS X Server, Mac Security, Ubuntu, Unix

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