Tuesday, April 15, 2025

Azure Bastion Developer - shared Bastion pool

 The Azure Bastion is useful for connecting securely to virtual machine without exposing the VMs to the internet using public IP's.

This however, requires a dedicated Bastion instance to be deployed and an AzureBastionSubnet.

With Bastion Developer, test/dev users can connect to the local IP of the VM via Bastion using a shared pool, so no dedicated setup required. The features are limited though. See here for more info.

To use, in the portal simply go to the VM -> Connect -> Bastion.

Add credentials and click Connect. This will open a remote session in the browser, see below:








Azure: Troubleshoot connectivity to a key vault with a private endpoint

 If you have a key vault that you can't reach there can be multiple reasons for this. Two of the main ones are DNS issues and firewall blocks.

This post will go over those two issues and show a couple of ways to test for connectivity.

When working in hybrid setups with an on-prem location connected to Azure either via VPN or ExpressRoute then it happens that you can create and see the key vault (this also goes for e.g. storage accounts and other PaaS services) but you get an error when trying to add a secret or other content to it. The error can mention e.g. "the connection to the data plane failed".

To troubleshoot, first we ensure that the local IP of the private endpoint can be resolved.

nslookup myown-keyvault.vault.azure.net

On Linux you can use the command dig to get slightly better lookup details than with nslookup:

dig myown-keyvault.vault.azure.net

This should resolve to a local IP. If it doesn't resolve at all or if it returns a public IP, there is something wrong with the DNS setup.

More info on troubleshooting DNS can be found here.

If that works, you can check for connectivity from your source. This can be done in a couple of ways and either of them is fine.

From Windows run:

tnc myown-keyvault.vault.azure.net -port 443

From Linux run:

nc -zv myown-keyvault.vault.azure.net 443

All data to a key vault goes over port 443, so if you have connectivity on that port and it can resolve the IP, then you should be good.

Alternatively try:

$(Invoke-WebRequest -UseBasicParsing -Uri https://myown-keyvault.vault.azure.net/healthstatus).Headers

Or from Linux:

curl -i https://myown-keyvault.vault.azure.net/healthstatus

There is more info on troubleshooting behind a firewall here.

Thursday, April 10, 2025

Azure: Adding KQL queries as Resource Graph queries

 Using the Resource Graph Explorer can be helpful to retrieve information about your Azure environment using KQL. If you have certain queries that you run on a frequent basis and want to save, this can be done under Resource Graph queries.

If they are saved as 'shared' queries they can be viewed and run by others. Private queries can only be seen by you.

Resource Graph queries can be added via code and it is also supported by Azure Verified Modules.

The below screenshot shows what it looks like, when a few queries have been added:


If you click one of the queries, it will show the query itself in a new window:


And on the Results tab, you can run the query directly:


The Bicep AVM files are available on Github, see link.

The queries can be placed in any resource group.

Here are some examples of more queries from MS.




Tuesday, April 8, 2025

Retrieve custom DNS server settings on VNets using Kusto (KQL)

 You can use Kusto Query Language (KQL) to retrieve information about your Azure environment across subscriptions.

It's a fast tool and very useful in larger environments with many subscriptions and resources.

The following example shows how to list all VNets in the environment including their custom DNS server settings.

Go to Azure Portal -> Azure Resource Graph Explorer

In the query window, add the following KQL:

Resources
where type == "microsoft.network/virtualnetworks"
extend dnsServers = properties.dhcpOptions.dnsServers
project id, name, dnsServers

Click: Run query

Result will look like below (custom DNS only set on one VNet):



You can download the content as a csv and import into xls for sorting and filtering.