Azure Migrate – Additional Firewall Rules

When deploying Azure Migrate Appliances to discovery servers, the appliance needs outbound internet access. In many IT environments, servers are disallowed internet access unless prescribed to certain URL sets. Gratefully Microsoft have given us a list of what they think is the list of URLs that the appliance will need to have whitelisted. This can be found here:


Once the appliance has booted up and your onto the GUI, you must ener your Azure Migrate Project key from your subscription and then authenticate to your subscription. We entailed the following error when attempting to resolve the initial key:

Azure Migrate Error

Failed to connect to the Azure Migrate project. Check the errors details, follow the remediation steps and click on ‘Retry’ button

The Azure Migrate Key doesn’t have an expiration on it so this wasn’t the issue. We had whitelisted the URL‘s but on the firewall we were seeing dropped packets:

13:40:41Default DROPTCP10.0.0.10:50860204.79.197.219:443
13:40:41Default DROPTCP10.0.0.10:50861204.79.197.219:80
13:40:41Default DROPTCP10.0.0.10:50857152.199.39.242:443
13:40:42Default DROPTCP10.0.0.10:50862204.79.197.219:80
13:40:42Default DROPTCP10.0.0.10:50858104.74.50.201:80
13:40:43Default DROPTCP10.0.0.10:5086352.152.110.14:443
13:40:44Default DROPTCP10.0.0.10:50860204.79.197.219:443
13:40:44Default DROPTCP10.0.0.10:50861204.79.197.219:80
13:40:45Default DROPTCP10.0.0.10:50862204.79.197.219:80
13:40:46Default DROPTCP10.0.0.10:5086352.152.110.14:443
13:40:46Default DROPTCP10.0.0.10:50859204.79.197.219:443
13:40:47Default DROPTCP10.0.0.10:5086440.90.189.152:443
13:40:47Default DROPTCP10.0.0.10:5086552.114.36.3:443
13:40:49Default DROPTCP10.0.0.10:5086440.90.189.152:443
13:40:50Default DROPTCP10.0.0.10:5086552.114.36.3:443
13:40:50Default DROPTCP10.0.0.10:50860204.79.197.219:443
13:40:50Default DROPTCP10.0.0.10:50861204.79.197.219:80
13:40:51Default DROPTCP10.0.0.10:50862204.79.197.219:80
13:40:52Default DROPTCP10.0.0.10:5086352.152.110.14:443
Subset of the dropped packets based on IP destination during connection failure

Reviewing the SSL certificates on these IP addresses, they are all Microsoft services with multiple SAN entries. We also had a look at the traffic from the developer tools in the browser:

We can see that the browser is trying to start a AAD workflow for device login, which is articulated in the onboarding documentation. Our issue was that the JavaScript for inside the browser session wasn’t located in the whitelist URLs. Reviewing the SAN entries in the certificates presented in the IP destination table we looked for ‘CDN’ or ‘Edge’ URLs.

The fix

The following URLs were added to the whitelist group for the appliance and problems went away.**************

Pimp my VS Code

Those who know me, know that I have a keen interest in software tools and exploring the various different ways that people use them. I take great joy in exploring custom or 3rd party plugins and add-ons to get the most out of the tools I use every day. From OS automation tools (like BetterTouchTool) to custom screen savers (Brooklyn is my current favourite), I love it all.

On a good day, I spend quite a bit of time in Visual Studio Code, my IDE of choice. VS Code has all that you need right out of the box, but why stop there? Heres a list of some of my favourite VS Code Extensions that I now consider essential when doing a fresh install.

Indent-Rainbow and Bracket Pair Colorizer 2 are must installs for me. Both really simple, change colours of indents and brackets so you can easily see them at a glance. Always useful when working with ident heavy languages like YAML.

GitLense is another essential if you are working with Git repositories. GitLense integrates lots of various Git tools and information into the editor. My favourite feature of GitLense is the current line blame, you can see it in the screenshot above which shows an unobtrusive annotation at the end of each line as you select it. The annotation shows commit information for that piece of code.

Beautify helps you make your code beautiful. Beautify can automatically indent Javascript, JSON, CSS, and HTML.

Better Comments makes your comments human readable by changing the colour of comments based on an opening tag. You can even define your own.

Source: Better Comments Documentation in Visual Studio Code

Next up, some extensions that I install to match the work I’m doing. In my day to day work, I’m regularly authoring infrastructure templates for Azure and AWS (ARM and CloudFormation). To assist with making this as simple as possible I install some specific extensions for syntax highlighting, autocompletion and even do some code snippet referencing.

Azure Resource Manager (ARM) Tools is a collection of extensions for working with Azure made by Microsoft. This one has lots of features so I’ll just pick a few. You can use the ‘arm!’ shortcut to create a blank ARM template with all the property you need – this one makes life so much better, spend less time lining up brackets in JSON and more time defining resources!

Image showing the arm template scaffolding snippet
Source: Azure Resource Manager (ARM) Tools Documentation in Visual Studio Code

Each time you use a snippet, you can also use tab complete to go through commonly modified configurations, again, less time reading documentation more time writing code!

Image showing snippet tab stops with pre-populated parameter values
Source: Azure Resource Manager (ARM) Tools Documentation in Visual Studio Code

CloudFormation Template Linter and CloudFormation Resource Snippets add some similar functionality for working with AWS CloudFormation templates. While neither of these are created by Amazon, they both do a good job at implementing similar functionality to the above ARM tools.

Next up is one of my new favourites, Dash, sorry Windows guru’s this one’s only on Mac. Dash is an API documentation browser which can hook into your VS code to quickly search documentation (from their 200+ built in doc sets, or add your own GitHub doc sets). Sounds boring, but I think it’s far from it. I’ve loaded mine up with lots of Microsoft Azure Documentation and AWS documentation. It’s really handy to be able to highlight a resource type or PowerShell Command, hit control + H and have the document reference instantly pop up, each time it saves me minutes.

Dash - Visual Studio Marketplace
Source: Dash Documentation in Visual Studio Code

Finally, my icon and colour theme I use VSCode Icons and Atom One Dark. This really comes down to personal preference. I like the syntax colour coding included in the Atom One Dark theme, I find it useful especially when writing PowerShell. VSCode icons is the most popular icons extension, and I’ve had no issues since installation.

Source: Atom One Dark Theme Documentation in Visual Studio Code

Thats my round up for my must have extensions. Are there any missing off this list that you think should be here? – Comment below with your must have extensions.

Cheers, Joel

Understanding Undocumented ARM Oddities

Over the past year I’ve been working pretty heavily with Azure Resource Manager (ARM) templates to create safe, reusable and consistent deployments of virtual infrastructure. When producing ARM templates, it’s important to understand what resource types are available, and what values to use in your template. I always use the Azure Template Reference to understand exactly how to define a certain resource type. However, sometimes you will run into situations where the Azure Template Reference is missing something that can be done in the Azure portal. So, how do we figure out how to template it if it’s not in the reference documentation?

Export Templates – Perhaps the quickest way to solve this problem is to use the native ‘Export Template’ blade in the Azure portal. For this, you will need to deploy your resource and configure it as you would like, using the Azure Portal. Once you have your resource ready, open the Export Template blade on your resource. This will create an automatically generated ARM template based on the current running state of your resource. From here, you can inspect the generated template and see if your undocumented settings or configuration has been captured in the generated template.

Download template

Azure Resource Explorer – Next stop is the Azure Resource Explorer which provides a visual interface for you to examine the Azure API’s. With the Azure Resource Explorer, you can explore the current running state of an Azure environment in JSON format. This can be very useful when attempting to reverse engineer an existing resource or environment. While Azure Resource Explorer isn’t returning data that can be directly used in an ARM template, it can be used as a mechanism to learn the syntax of resource properties that are missing from the Azure Template Reference.

This image has an empty alt attribute; its file name is 13nov1.png

When issues are encountered with undocumented resources, typically the fastest way to resolve the issue is by manually deploying the resources using the Azure Portal (clicky clicky) then reverse engineering the ARM template with a combination of using the Export Templates function and Azure resource explorer. Going down the route of doing everything in ARM templates, can lead to a lot of trial and error before getting a fully automated deployment, for now at-least.



Undocumented ARM Oddities – .Net Core App Services

Every once in a while, when working with ARM templates you come across something that is missing from the official Microsoft ARM template reference. In my case yesterday, I was looking to update the configuration of an Azure App Service to use the DotNetCore stack (rather than .NET 4.8).

While I initially thought this would be a quick job to simply look up the ARM reference and make the required changes, I found that there was nothing about DotNetCore in the ARM reference. Funny enough, there is a value for “netFrameworkVersion”, but don’t be deceived, if you are looking to setup DotNetCore – this value is not for you (this is for regular .Net only).

To better understand the problem, I Clickly Clikcy’d in an App Service and configured it for DotNetCore (Clickly Clicky is our lingo for deploying infrastructure using the portal rather than a CLI or template). With this, I attempted my usual trick of exporting a template and observing the JSON it spits out. However, much to my amazement I couldn’t see any reference to dotnetcore in there at all.

In the end it was the Azure Resource Explorer which came to my rescue. Used the tool to explore the example I created and found a value called “CURRENT_STACK” in the properties of the “Microsoft.Web/sites/config” resource type.

After playing this this for a while, I was able to translate this into my ARM template with the following JSON.

    "type": "Microsoft.Web/sites",
    "name": "[variables('WebSiteName')]",
    "apiVersion": "2020-06-01",
    "location": "[resourceGroup().location]",
    "kind": "app",
    "properties": {
        "siteConfig": {
            "metadata": [{
                "name": "CURRENT_STACK",
                "value": "dotnetcore"

Hopefully this helps anyone who encounters this problem.



Azure Bastion – Unable to query Bastion data.

I’ve recently setup Azure Bastion to give external users/vendors access to resources via RDP or SSH following these instructions:

The key permissions outlined in the prerequisites at point 3 are:

  • A virtual network.
  • A Windows virtual machine in the virtual network.
  • The following required roles:
    • Reader role on the virtual machine.
    • Reader role on the NIC with private IP of the virtual machine.
    • Reader role on the Azure Bastion resource.
  • Ports: To connect to the Windows VM, you must have the following ports open on your Windows VM:
    • Inbound ports: RDP (3389)

My scenario is to invite a guest AAD account, add them to a group and grant the group access as per below:

  • Grant Contributor role to the resource group that has the VM’s for the application.
  • Grant Reader role to the resource group that has the Bastion host.

This way the guest user logs into the Azure Portal complying with our conditional access policy and then they are presented with only the resources they have read or higher access too. In this scenario that is the two resource groups outlined above.

The guest user locates the virtual machine they wish to connect and then chooses Connect > Bastion > Use Bastion the following error message is presented.

Error Message:

“Unable to query Bastion data”

Initially working with Microsoft support we found that granting reader access at the subscription level gave the user permission to in-act the Bastion service, which simply give a username and password input.

These permissions were too lacks as a workaround and exposed a lot of production data to accounts that didn’t really have any business looking at it.


[12/11/2020] The case is on-going inside Microsoft and I will leave a definitive response when I get the information. I’ve done some further investigation what would be the least amount of additional ‘Reader‘ permissions are required. I’ve found the following permissions are required in my scenario:

  • Reader permissions on the Virtual Network that has the ‘AzureBastionSubnet‘ subnet.
  • Reader permissions on the Virtual Network that has the connected virtual machine network interface.

In my scenario, the virtual machines are located in a development Virtual Network that is peered with the production Virtual Network which has the subnet ‘AzureBastionHost‘. So I had two sets of permissions to add. After applying the permissions you may need to get a coffee and return to the portal as it took 5-10 minutes to kick in for me.

Hope this helps someone that has done some googling but is still scratching their head with this error message.