Unsolved Mysteries: The time Wireshark actually *solved* the problem

We just got back from a ticket for an issue to do with a new lighting control system for one of the theaters on campus. The system includes a layer-3 switch, and the setup process involves assigning a static IP to a laptop that is directly connected via Ethernet to the switch. The theater techs followed the steps in the setup guide to the letter, but no matter how much they would adjust the settings, and even after 45 minutes on the phone with the vendor's tech support, the laptop still could not ping the switch. That's when they called us.

We repeated the setup process, and did our normal network troubleshooting - verifying IP addresses, switching to another network cable, even switching to another laptop - but we didn't have any better luck than they did. Even Nmap couldn't see anything. So, we opened up Wireshark to try to see what the computer and switch may have been trying to send to each other.

Lo and behold, as soon as Wireshark began capturing packets, the laptop and switch could connect to each other, and we were able to use the lighting control program to send configurations to the switch and other equipment. As soon as we stopped the Wireshark capture, though, the problem returned. The only way that these two pieces of hardware can communicate is if Wireshark is running.

This works well enough for what the theater techs need it for, as once the program is uploaded to the equipment, it operates as a self-contained unit. We forwarded our findings on to the vendor's support, and advised the techs to make sure Wireshark is capturing packets if they ever need to connect to the system.

There's no way that Wireshark should help in this way, right?

Downloading GarageBand loops for Munki deployment using appleLoops.py

Among other applications, we deploy Apple's GarageBand using Munki. GarageBand can be installed without too much trouble, but on first run, it prompts the user for an administrator password so that it can download and install a set of instrument loop packages. Of course, if the user isn't an administrator - for example, a student in a lab - they won't be able to allow this installation, and will therefore be unable to launch GarageBand.

So, to avoid this problem, it's standard practice to download the loop packages for deployment through something like Munki or Jamf. The traditional way to do this involved opening GarageBand and, before entering your administrator credentials, copying the installer packages out of a path located deep within /var/folders/.... Unfortunately, at least with our modern version of GarageBand 10.3.2, this doesn't seem to be good enough: the set of packages that are downloaded, when installed onto another computer with a fresh install of GarageBand, don't satisfy the application, and it prompts to download them again. It's possible that I made some mistake, but I tried it twice, and it didn't work either time.

Fortunately, some Googling turned up a GitHub repository for a project called appleLoops.py, by Carl Ashley, that ultimately solved our issue. appleLoops.py makes it easy to download loop packages for GarageBand, Logic Pro X, and MainStage 3, and can optionally install these packages in deployment mode, usable from products like Munki and Jamf. It even lets you specify a local cache location that clients will use to download packages so that you can avoid slow or expensive transfers over the Internet.

For our purposes, simply downloading the packages is good enough, so here's how I did it:
1. Download the appleLoops.py project from GitHub.

2. Create a folder to store the loops that you will be downloading. I made this folder as a subdirectory of the appleLoops project folder, but it can be anywhere on your computer, or even a network location to which you have write access.

3. Run the appleLoops.py script:
sudo ./appleLoops.py --apps garageband --destination ./loops --mandatory-only
(If you also want the larger set of optional loops, add --optional-only to the command line. Despite both flags saying "only", they actually do combine without issue.)

4. After the loops have finished downloading, configure your management system of choice to deploy them to clients. If you don't use a management system like Jamf or Munki, you can easily write a shell script to install all of the loops packages manually:
#!/bin/bash

for pkg in $( ls *.pkg ); do
    echo "Installing $pkg"
    installer -pkg $pkg -target /
done

5. After the loops have installed, GarageBand should open without prompting for administrator credentials.

Whitelisting Windows Store applications on Windows using secpol.msc

As part of PCI compliance, we are required to restrict the applications which users are able to access on our payment office PCs to those on a specific whitelist. One wrinkle we've run into as part of migrating from Windows 7 to Windows 10 is that our older GPO-based method of restricting applications does not apply to newer Windows Store/Modern apps, including Microsoft Edge and Skype. This wrinkle has, so far, kept our payment PCs on Windows 7 for PCI compliance reasons.

Luckily, I discovered that it is possible to use a different method to whitelist applications: secpol.msc.  This is the Local Security Policy editor, reminiscent of the Local Group Policy editor gpedit.msc, and it allows you to create a software restriction policy to control what applications can and cannot run on a PC.

To create a software restriction policy to create an application whitelist, including Windows Store/Modern apps, follow these steps:

1. Open secpol.msc.

2. Right-click on "Software Restriction Policy", then on "New Software Restriction Policies."

3. In the "Security Levels" folder on the left, right-click on the "Disallowed" setting, then on "Set as default." This sets Windows to disallow access to all applications by default, except for those specifically whitelisted in the "Additional Rules" section below.

4. Right-click in the empty space in the "Additional Rules" folder, then on "New Path Rule...".

5. Enter the path of the application or folder that you wish to control. In this example, I am adding a rule to disallow all applications and apps in the C:\Program Files\WindowsApps folder, which includes things like the Calculator and Notepad apps. Click OK.

6. Add more rules to cover all of the applications you wish to control. As you can see in the screenshot below, I have also added a rule to disallow C:\Windows\SystemApps\*Edge*, in order to block the Microsoft Edge web browser from running. 

Note: You most likely do not want to block C:\Windows\SystemApps as a whole, because Microsoft has app-ified various parts of the operating system, including the Start menu and File Explorer. If you disallow this folder, you will lose access to these parts of the operating system until the policy is relaxed.

That's pretty much it! As you can see in the screenshots above, there are two entries that are automatically created when you create the software restriction policy: one for %HKLM [...] ProgramFilesDir%, and one for %HKLM [...] SystemRoot%. 

%SystemRoot% includes vital parts of the operating system, so it is not advisable to disallow access to this folder on a blanket level. %ProgramFilesDir% covers everything in the Program Files directory, meaning that by default some applications will still be allowed to run, even with the default policy set to disallow - Microsoft Office is an example of this. If you want to block these applications, simply change that entry from unrestricted to disallow.

In order to whitelist an application, you would do the same thing: create a new additional rule, but instead of specifying that it should be a "disallow" rule, choose "unrestricted" instead.

To make your changes take effect, log out and back in.

Windows User Profile Migration with Profwiz

At my new place of employment, we migrate Windows user profiles from one machine to another using the ForensiT Domain Migration User Profile Wizard, or Profwiz for short. This tool works somewhat differently to the Windows Easy Transfer tool, which handles user profile creation and data migration for you, in that Profwiz only configures profiles in-place to work with data copied from another computer. This means that you are free to use whatever format you wish to store the transferred data, versus the Easy Transfer tool, which uses its own proprietary .MIG format, which in the past I have found can become corrupt and unrecoverable over a certain size. Profwiz also does not create the user profile for you, so you need to do that yourself, but once you run Profwiz, everything "just works." An additional plus to Profwiz is that, in order to use the Easy Transfer tool, you must be able to boot and log into the computer, but Profwiz will work as long as the hard drive is readable.

The Profwiz user guide explains in detail the many capabilities of the tool, along with how you can set up a distribution file with many settings pre-entered to save time during the actual migration process. However, if you're just doing a few migrations, it is easy enough to run the tool manually. To perform a user profile migration on Windows with Profwiz, follow these steps:

1. Create a local profile on the new computer with the same username as on the old computer. If the profile on the old computer was a domain account, don't worry, as Profwiz will take care of that.
2. Copy the user's profile data from their old hard drive or a backup location to the profile on the new machine that you just created. Make sure to copy AppData and any other hidden folders as well to make sure that things like browser bookmarks and application configurations are migrated correctly. (Be sure to keep the old hard drive for at least a little while as an additional backup!)
3. Download Profwiz. Note that even though it downloads as an .MSI, it doesn't really install anywhere, and rather just dumps the .EXE in the same directory. You could probably just re-use the same .EXE for future migrations.
4. Run Profwiz: (Screenshots may be found starting on page 29 of the user guide)
1. Select the computer to which you are performing the migration. For most cases, you will probably choose "Local Computer", though it is possible to perform migrations over the network. In this guide, I will focus on local migrations. [Next >]
2. Select the user profile(s) to be migrated. The free Personal edition of Profwiz only allows a single profile to be migrated at a time, but the paid Corporate edition allows you to select several. You will want to select the profile(s) you created and copied data to in the steps above. You may also check the boxes for "Disable Local Accounts" or "Delete Local Accounts" if you wish to remove the local accounts you created after the migration is complete. (This is useful if your environment mandates that only domain accounts be used.) Check the box(es) next to the profile(s) to migrate, and then [Next >].
3. Enter the name of the domain to which the new user profile belongs. If the computer is not already joined to the domain, you can click the "Join Domain" checkbox below the domain box. If the computer will not be joined to a domain, click the drop-down arrow for the box and select the local computer name. (Azure AD accounts are also supported, but are outside the scope of this writing - please refer to page 38 of the user guide for that information.)
4. Below the domain box, enter the name of the account that should be used for the new profile. This will usually be the same as the username you gave the new profile when you created it. If desired, check the box for "Set as default logon" (useful for single-user scenarios), then [Next >].
5. Profwiz will run through several steps to set the appropriate access control list (ACL) settings for the new profile to allow the specified domain user account to access the files and folders contained within, to join the domain, and anything else you specified for it to do. When done, click [Next >].
6. You will be prompted to reboot the computer after Profwiz is finished.

After the computer reboots, you should be able to log in as the migrated user (assuming that you have their credentials), and everything should be as it was on the old computer. Profwiz does not migrate things like printers or applications, so you will still need to install those by hand, but it does greatly simplify the task of moving a user profile from one machine to another.

Python indentation in the Jamf Pro script editor

The Jamf Pro web interface includes a built-in script editor which allows you to make changes to existing scripts, or to compose new scripts entirely within the Jamf Pro interface. There is one gotcha with this editor that is not really Jamf's fault, and one that experienced programmers can probably see coming: when working with Python scripts, you need to be sure to use consistent indentation, or else you'll see policy failures with errors indicating so.

What happens, at least in my case, is that I will write a Python script in Notepad++, nano, or some other editor that I have set up to replace tab characters with spaces, then copy-and-paste that script into the Jamf Pro web interface. Then, later on, when I go to edit the script, I'll hit the tab key, and the editor dutifully inserts a tab character. This confuses Python, which uses differing levels of indentation to determine code blocks (versus C-style languages, which use curly brackets).

When this happens, you can manually correct the indentation by replacing tabs with spaces, or you can copy-and-paste the indentation from another line at the same level. Another way to get around this, of course, is to copy the script from the Jamf Pro interface into your text editor of choice, make your changes, then copy it back into Jamf Pro, which avoids this issue, but adds some extra work.

This isn't a problem with bash or other scripting languages, as these aren't so strongly influenced by indentation. This also isn't fundamentally a problem with the Jamf Pro script editor, which inserts the character that you're asking it for, but more of a problem with muscle memory working against you when moving between two editors that are not set up in exactly the same way.

Built-in Unix tools on Windows 10

As you may be aware, Windows 10 supports running a full Linux/bash environment via the Windows Subsystem for Linux (WSL). This can be installed from the Windows Store, or via PowerShell, and gives you access to the tools provided by your chosen distribution without the need to reboot or start up a VM.

However, Windows 10 also (as of April 2018) includes a few very useful tools without even needing to enable the WSL. These tools are:

• ssh - "Secure SHell", allowing you to access Linux, Unix, macOS, and other related operating systems remotely from the command line
• curl - "Client URL", which you can use to upload/download files and make requests to web servers from the command line
• tar - "Tape ARchive", which allows you to combine many files into one archive for ease of transport and/or compression

These tools are now included and enabled by default in Windows 10, and can be accessed from either cmd.exe or PowerShell. One difference between these two shells is in the curl command: in cmd.exe, this runs as a regular executable, with the same flags that you would expect on a Unix machine; however, in PowerShell, curl is an alias to the Invoke-WebRequest cmdlet, so its arguments are not the same. You can get around this by specifying curl.exe in PowerShell to get the standard behavior.

These tools, ssh in particular, are very useful in my daily work as they allow me to remote into Macs without needing to have PuTTY or some other terminal installed. tar is also useful because it helps reduce the slowness you may encounter when copying many small files; by combining these files into one larger archive, you can avoid the time overhead required to start and stop the copying operation for each, only paying that time penalty once.

These tools are also useful for scripting, even (or especially) in batch files. PowerShell provides cmdlets that replicate the functionality of curl, for example, but now that it's included by default, you can easily write a plain old .bat file to download a file from a website, or even to make a HTTP request to a server by POSTing to a URL.

Microsoft Edge on Chromium: First Impressions

I recently saw a Slashdot article that Microsoft just released the first "dev channel" build of its new Chromium-based Edge browser, and figured that I would give it a try and document my first impressions of this "new" browser.

Looks

Visually, the two browsers are very similar. In the screenshot below, Google Chrome is on the left, and Microsoft Edge is on the right. As you can see, the window chromes - the title bars, address bars, etc. - are not very different between the two.

The situation is similar when you click the menu button in the top-right corner of each browser. Microsoft has altered Edge's menu so that it is not exactly reminiscent of either Google Chrome or the old Edge browser, but combines the styles and functionality of the two.

The biggest visual distinction from Chrome that I've seen in my very brief trial of the new Edge is in the settings page. Edge's settings page hardly resembles Chrome's; in fact, it reminds me much more of Firefox's settings page.

The big functionality difference here is that Google Chrome allows you to sign in with a Google account, while Edge allows you to sign in with a Microsoft account. Once you get past the visual differences, though, both settings pages actually work pretty much the same - for example, the "Site Permissions" portion of both offer the same choices of plugins or parts of pages that can be enabled or disabled, and the "About" portion of each shows the version number and automatically tries to install available updates when opened.

Extensions

As you may be able to see in the screenshots above, I have already installed uBlock Origin into the new Edge browser. The interesting and exciting thing is that I did so from the Chrome app store. 

Microsoft provides an extension store for Edge, which in the past would've been the only way to get them. Now, on the new Edge's Extensions page, there is a button in the bottom corner labelled "Allow extensions from other stores." The "Learn More" link gives instructions on how to enable this setting, and how to go to the Chrome Web Store to install extensions. These extensions ask for exactly the same permissions, etc., as in Chrome (of course), and otherwise work identically in both browsers.

Performance

As expected due to the fact that both browsers use the Chromium engine, their scores on the Basemark Web 3.0 test are basically the same: 344.67 for Google Chrome, 354.78 for the new Edge browser. The score breakdown shows that the two are close enough that the point difference doesn't really mean anything, and practically, they (and most web browsers) work well enough that you won't really notice any differences anyway.

Summary

Google Chrome and the new Microsoft Edge web browser, at first impressions, are the same thing. What works in Chrome should work in new Edge, and vice versa - pages will render the same, they will be about as fast as each other, and extensions from Chrome will work in Edge (and, presumably, vice versa with new Edge extensions.)

I'm not sure how I feel about this. On the one hand, as an IT person, it would be great if a clean install of Windows gave me a usable web browser, which will now be available with the new Edge. It's also great that I can use the same extensions in both browsers, and that webpages should look and work the same in both. Microsoft Edge, as hard as it is to believe, is now a good browser.

On the other hand, I don't know if it's good for the web - which is supposed to be a decentralized, diverse system - to lose out on one if its major rendering engines (Edge's EdgeHTML engine is/was a fork of Internet Explorer's Trident.) We all remember the bad old days when it was IE6 or nothing, and webpages employed a lot of not-exactly-standards-compliant techniques to make themselves look and feel right, which caused issues when Firefox and other new browsers came on the scene. Will we see a return to that world when every browser, or at least most, are really just copies of Chrome? Sure, Chromium is open-source, but if everyone uses the same open-source base, the biggest contributors essentially decide the direction of the web. I just hope that Google and its contributors stick to the motto of "don't be evil."