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Tiny Deathstars of Foulness

This is the first page of a 5 page piece I just finished writing for MacTech. After the last episode of the MacAdmins podcast though, I wanted to go ahead and get some of the information out there. For a much more detailed analysis, check out MacTech! Apple has a number of different logging APIs. For the past few releases, Apple has tried to capture everything possible in logs, creating what many administrators and developers might consider to be a lot of chatter. As such, an entirely new interface needed to be developed to categorize and filter messages sent into system logs.

Writing Logs

The logger command is still used to create entries in system logs. However, if you are then using tail to view /var/log/system.log then you will notice that you no longer see your entry being written. This is because as the logs being created in macOS have gotten more complex, the tools to read and write those logs has gotten more complicated as well. Let’s take a simple log entry. Below, we’ll write the string “Hello Logs” into the system log. To do so, use the –i option to put the process id of the logger process and –s to write to the system log, as well as to stderr. To make the entry easier we’ll tag it with –t followed by the string of the tag. And finally, we’ll quote the entry we want written into the log. This is basically the simplest form of an entry: logger -is -t krypted "Hello Logs" Once written, use the log command to read your spiffy new entries. This isn’t terribly different than how things worked previously. If you’re a developer, you will need to note that all of the legacy APIs you might be using, which include asl_log_message, NSLog, and syslog, have been redirected to the new Unified Logging system, provided you build software for 10.12 (you can still build as before for 10.11, iOS 9, tvOS 10, and watchOS 3 and below). These are replaced with the os_log, os_log_info, os_log_debug, os_log_error, os_log_fault, and os_log_create APIs (which correspond to various levels of logs that are written).

Reading Logs

Logs are now stored in the tracev3 formatted files in /var/db/diagnostics, which is a compressed binary format. As with all binary files, you’ll need new tools to read the files. Console has been updated with a new hierarchical capability and the ability to watch activities, subsystems, etc. The log command provides another means of reading those spiffy new logs. To get started, first check out the man page: man log That “Hello Logs” string we used earlier is part of a message that you can easily view using the ‘log show’ command. In the below example, we’ll just run a scan of the last 3 minutes, using the –last option, and then providing a –predicate. We’ll explain those a bit later, but think of it as query parameters – here, we’ll specify to look for “Hello Logs” in eventMessage: log show --predicate 'eventMessage contains "Hello Logs"' --last 3m Filtering the log data using “eventMessage CONTAINS “Hello Logs”” shows us that our entry appears as follows:
Timestamp                       Thread     Type        Activity             PID 2017-03-23 23:51:05.236542-0500 0x4b83bb   Default     0x0                  88294  logger: Hello Logs ——————————————————————————————————————– Log      – Default:          1, Info:                0, Debug:             0, Error:          0, Fault:          0 Activity – Create:           0, Transition:          0, Actions:           0

March 26th, 2017

Posted In: Mac OS X, Mac OS X Server

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Posted a Huffington Post article from my notes from the WWDC keynote. Hope you enjoy!
Apple kicked off WWDC (World Wide Developers Conference) today, with a Keynote that showcased some of the upper tier of talent and management within Apple. As a former WWDC speaker, I watch the keynote and most sessions through the remainder of the week religiously. Here, you see what’s coming in the fall releases of the four operating systems: macOS, watchOS, iOS, and tvOS (for Macs, Apple Watches, iPhones and iPads, and Apple TVs respectively).
Screen Shot 2016-06-14 at 2.01.07 PM PS: macOS autocorrects to tacos. Mmmmm, tacos…

June 14th, 2016

Posted In: Apple TV, Apple Watch, iPhone, JAMF, Mac OS X, Mac OS X Server

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AppleTVs automatically update. They do so using a process similar to how iOS updates, but instead of looking at the feed I posted in http://krypted.com/mac-security/how-the-os-x-caching-server-caches-updates/, they look at http://mesu.apple.com/assets/tv/com_apple_MobileAsset_SoftwareUpdate/com_apple_MobileAsset_SoftwareUpdate.xml. The AppleTV feed is similar to that available for iOS updates, with each dictionary having roughly the same data:
<key>ActualMinimumSystemPartition</key>
<integer>1482</integer>
<key>Build</key>
<string>13Y6234</string>
<key>InstallationSize</key>
<string>0</string>
<key>MinimumSystemPartition</key>
<integer>1534</integer>
<key>OSVersion</key>
<string>9.2</string>
<key>ReleaseType</key>
<string>Beta</string>
<key>SUDocumentationID</key>
<string>PreRelease</string>
<key>SUInstallTonightEnabled</key>
<true/>
<key>SUMultiPassEnabled</key>
<true/>
<key>SUProductSystemName</key>
<string>iOS</string>
<key>SUPublisher</key>
<string>Apple Inc.</string>
<key>SupportedDeviceModels</key>
<array>
<string>J42dAP</string>
</array>
<key>SupportedDevices</key>
<array>
<string>AppleTV5,3</string>
</array>
<key>SystemPartitionPadding</key>
<dict>
<key>1024</key>
<integer>1280</integer>
<key>128</key>
<integer>1280</integer>
<key>16</key>
<integer>160</integer>
<key>256</key>
<integer>1280</integer>
<key>32</key>
<integer>320</integer>
<key>512</key>
<integer>1280</integer>
<key>64</key>
<integer>640</integer>
<key>768</key>
<integer>1280</integer>
<key>8</key>
<integer>80</integer>
</dict>
<key>_CompressionAlgorithm</key>
<string>zip</string>
<key>_DownloadSize</key>
<integer>856434408</integer>
<key>_EventRecordingServiceURL</key>
<string>https://xp.apple.com/report</string>
<key>_IsZipStreamable</key>
<true/>
<key>_Measurement</key>
<data>cm8k41In38EOJEj20IwJp5Suskw=</data>
<key>_MeasurementAlgorithm</key>
<string>SHA-1</string>
<key>_UnarchivedSize</key>
<integer>3438532888</integer>
<key>__AssetDefaultGarbageCollectionBehavior</key>
<string>NeverCollected</string>
<key>__BaseURL</key>
<string>
http://appldnld.apple.com/tvOS9.2//031-53364-20160321-7C5E21F2-E7B5-11E5-89F7-525CBD379832/
</string>
<key>__CanUseLocalCacheServer</key>
<true/>
<key>__RelativePath</key>
<string>
com_apple_MobileAsset_SoftwareUpdate/f58f4b324a9c717ea57b0cee063473a99d9e9e92.zip
</string>
To construct a URL to a zip, you would then simply merge the _BaseURL and the _RelativePath to the asset from the feed for a given model, in the above example, ending up with the following URL to manually download tvOS 9.2 for AppleTV 5,3:
http://appldnld.apple.com/tvOS9.2//031-53364-20160321-7C5E21F2-E7B5-11E5-89F7-525CBD379832/com_apple_MobileAsset_SoftwareUpdate/f58f4b324a9c717ea57b0cee063473a99d9e9e92.zip
BTW, Applednld is load balanced between 17.253.29.201 and 17.253.29.202, both within Apple’s Class C.
You don’t need two / characters in the path, but if you take the same process from my earlier post, you end up with
http://10.1.1.2:55491/tvOS9.2/031-53364-20160321-7C5E21F2-E7B5-11E5-89F7-525CBD379832/f58f4b324a9c717ea57b0cee063473a99d9e9e92.zip?source=appldnld.apple.com

April 27th, 2016

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

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