Azure Virtual Network
An Azure networking service that is used to provision private networks and optionally to connect to on-premises datacenters.
2,256 questions
Unable to connect to remote resource from app service via virtual network
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Peter Mello
45
Reputation points
I am unable to connect (TCPPING) a remote resource (IP address) to an App Service using a Virtual Network Integration. Connectivity (TCPPING) from Console of App Service worked a few months ago.
App Service -> Virtual Network 1 (Address space 192.168.2.0/24) - Peered with Virtual Network 2
Virtual Network 2 (Address Space 172.16.0.0/16) -> Local Connection
Outbound internet traffic = OFF (unchecked)
Peering status = Fully Synchronized
Peering state = Succeeded
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ChaitanyaNaykodi-MSFT 24,231 Reputation points Microsoft Employee2024-06-04T22:11:18.0033333+00:00 Thank you for reaching out.
The issue observed above might be due to any NSG blocking the connectivity within the virtual network. In order to test this you can use IP Flow verify functionality of Network Watcher. If the Local Connection mentioned above is a VM then it will be easy to run the test above or else you can deploy a test VM in the peered VNET to run IP flow verify test.
As documented here to confirm that virtual networks are peered, you can check effective routes. Check routes for a network interface in any subnet in a virtual network. If a virtual network peering exists, all subnets within the virtual network have routes with next hop type VNet peering, for each address space in each peered virtual network.
Hope this helps! Thank you!
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Peter Mello 45 Reputation points
2024-06-05T14:57:06.15+00:00 Thank you @ChaitanyaNaykodi-MSFT I created another subnet in the same address space as the application subnet as shown below (VM-Subnet). I added a VM in the VM-Subnet and then ran IP Flow verify to test connectivity to the external IP. This was successful. However, I am unable to TCPPING from the App Service which is connected to the App-Subnet. Both tests (VM and App) attempted connectivity to ports 80 and 443.
It was helpful to know that the VNET can connect to the external IP from the VM-Subnet so now I am unsure what it is about the App-Subnet that is causing an issue. As shown below, the App-Subnet is Delegated to Microsoft.Web/serverFarms which is required apparently.
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ChaitanyaNaykodi-MSFT 24,231 Reputation points Microsoft Employee
2024-07-02T00:16:05.3766667+00:00 Apologies for the delayed response here.
If you are still facing this issue I think to troubleshoot the exact issue I think we will need specialized 1:1 session, where a support engineer can have a screen share session to pin point the issue. If you have a support plan you may file a support ticket, else please refer to my private message here. Thank you!
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