Update how-to-access-azureml-behind-firewall.md

Add more details about vs code port selection

Author: lebaro-msft

articles/machine-learning/how-to-access-azureml-behind-firewall.md

@@ -197,7 +197,9 @@ To install the Azure Machine Learning extension on Kubernetes compute, all Azure
 
 
 ## Scenario: Visual Studio Code
+Visual Studio Code relies on specific hosts and ports to establish a remote connection.
 
+### Hosts
 The hosts in this section are used to install Visual Studio Code packages to establish a remote connection between Visual Studio Code and compute instances in your Azure Machine Learning workspace.
 
 > [!NOTE]
@@ -212,6 +214,9 @@ The hosts in this section are used to install Visual Studio Code packages to est
 | `raw.githubusercontent.com/microsoft/vscode-tools-for-ai/master/azureml_remote_websocket_server/*` | Used to retrieve websocket server bits that are installed on the compute instance. The websocket server is used to transmit requests from Visual Studio Code client (desktop application) to Visual Studio Code server running on the compute instance. |
 | `vscode.download.prss.microsoft.com` | Used for Visual Studio Code download CDN |
 
+### Ports
+You must allow network traffic to ports 8704 to 8710. The VS Code server dynamically selects the first available port within this range.
+
 ## Scenario: Third party firewall or Azure Firewall without service tags
 
 The guidance in this section is generic, as each firewall has its own terminology and specific configurations. If you have questions, check the documentation for the firewall you're using.