We deploy to Azure app services and to ensure secure traffic between each service they are configured with out bound traffic on a virtual network subnet. Each app service must have it's own subnet, which is understandable, but to allow the app services to communicate we are having to add inbound ip restrictions for each subnet, on each app service.
As all the subnets for all the app services within an environment are on the same virtual network we were expecting the traffic to route between the subnets. In that way by connecting each app service to an out bound subnet and allowing traffic back in on that subnet it would also allow traffic from the other subnets of the virtual network.
I've read here Azure: Routing between subnets a response that state "Azure routes traffic between all subnets within a virtual network, by default. You can create your own routes to override Azure's default routing." but that does not appear to be happening for us.
Is there a setting we need to change or a route that must be added to allow us to have a single inbound rule from the virtual network that allows all traffic from all subnets of the virtual network.
We are splitting our process into micro app services but this is making security of inter-app traffic complex as each time we add an app service we must update all others with an additional inbound rule before it can communicate.
We also have a similar issue with managing access to the azure sql database where we have connected the sql to a subnet in the virtual network but traffic from the app services cannot access over that subnet.
Any advice please?
Related
Why do we have to create a new subnet or add the app service to an empty subnet in our vnet?
I don't understand the reasoning since I'm trying to use my app service (function app) as a reverse proxy to access the resources in the vnet.
By default, the Azure function is a PaaS as the other Azure Platform-as-a-Services that have inbound and outbound traffic over the Internet. We can host our applications without the need to worry about the maintenance of the servers and their operating systems.
To use Azure Functions to connect to resources in an Azure virtual network, we can use the VNet integration feature. To use this feature, we need to create a subnet in the virtual network for your function app to use. VNet Integration must be configured to use an empty subnet. It doesn't matter that your functions use a different subnet than your VM. The virtual network automatically routes traffic between the two subnets. Read Connect your function app to the virtual network
The extra empty subnet is used to hosting your app instance. To let the app instance outbound traffic work like from a VNet, Azure mounts NICs with assigned private IP addresses in that subnet. With VNet integration, your function app is connected to both the internet and your virtual network.
For more information, you may read How regional VNet Integration works and How gateway-required VNet Integration works
For an app to access resources in a Virtual Network, it needs to be either part of that network, or use a VPN gateway, which in turn can be used access resources inside the Virtual Network.
App Services provides 2 methods to communicate with resources in the Virtual Network:
Regional VNet Integration
Gateway-Required VNet Integration
With Regional VNet Integration, the infrastructure allocates a private IP interface on the VM that is hosting your Web App. This interface is allocated an IP address from the integrated subnets address prefix. This interface is later used to communicate with the VNet hosted resources. This is in a way similar to how IaaS VM work, however the limitation of this interface is that it can be only used for making outbound connections.
This way, if the ASP is configured to scale out to multiple VM's then each VM is allocated a corresponding private IP interface. However, the allocation of these IP address is limited to the subnets Address prefix. Nancy has already included this in her post. App Services have overlapped recycling so during scale up/maintenance, the App Service Plan may run on twice the number of VM's to ensure minimal downtime. However this also means, that the Integrated Subnet should have sufficient addresses available, so that these allocations can happen.
The IP Address of this interface is exposed via the environment variable WEBSITE_PRIVATE_IP. Here is a screenshot of my Kudu Console
If your site is running on multiple instances, then you can use the Instance menu to toggle through the instances.
With Gateway-required VNet Integration, there is a pre-requisite of provisioning a Virtual Network route-based gateway configured with an SSTP point-to-site VPN. In this case, the VM's hosting the Web App download the VPN package on the respective VM's to setup a VPN, and this is used to connect to the resources in the Virtual Network.
Even here, you can use the WEBSITE_PRIVATE_IP environment variable to see the IP Address used by the VPN client on the App Service VM.
HTH,
Kaushal
When setting up the Backend pools of an Azure Application Gateway, I want to set a specific VM in the pool.
This VM is in another VNet, and I've set up peering between the App Gateway's VNet and the VM's VNet.
Still, when I choose Virtual Machine as the target type of the Backend pool, the list is empty and I don't see any VM.
What's the problem? Am I missing something?
It seems that you only could see VMs in the same VNet as the application gateway located when you select the virtual machine as the target type of the backend pool.
If you have VNet peering, you can just add the internal IP of the VM to target the backend pool.
A backend pool routes request to backend servers, which serve the request. Backend pools can contain:
NICs
Virtual machine scale sets
Public IP addresses
Internal IP addresses
FQDN
Multitenant backends (such as App Service)
If you use internal IPs as backend pool members, you must use virtual
network peering or a VPN gateway. Virtual network peering is supported
and beneficial for load-balancing traffic in other virtual networks.
Reference: https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-components#backend-pools
I need to close a port 8010 on one of my app service on Azure. Is it possible to configure ports on app service?
In the App Service shared tenant environment, it is not possible to block specific ports because of the nature of the infrastructure.
But in App Service Environment(ASE), you have full control over inbound and outbound traffic. You can use Network Security Groups to restrict or block specific ports.
An ASE always exists in a virtual network, and more precisely, within a subnet of a virtual network. You can use the security features of virtual networks to control inbound and outbound network communications for your apps.
So, you need to create app service, virtual network. Then deploy app service to virtual network. (The vnet applies asg rules)
follow steps:
1.create a virtual network and make sure it is in the same location with your app service.
2.create a network secure group.(also make sure in the same location, In my side all of location is 'Central US')
3.add security rules of your nsg. Inbound or Outbound.
3.create a subnet in the vnet. Use the network secure group that you create above.
4.deploy your app service to the subnet of virtual network that you create above.
Finally, the app service deploy to the subnet of virtual network and the subnet virtual network use the network secure group which blocks specific ports. So your app service also block specific ports.
Please let me know if you have more problems.
We are using Azure Application Gateway for our site, and we are getting few people scraping our site. We want to block their IP at gateway level, as we don't want to configure the same blocks in every web service.
We can not find the way of blocking IPs using only the gateway or its virtual network. Had anybody the same problem and can illuminate our path?
You could deploy Application Gateway in a virtual network. If so, you will have a dedicated subnet for this Application Gateway. This subnet can only contain Application Gateways. You could associate an NSG to this subnet. If so, you could restrict inbound and outbound traffic from this Application Gateway subnet via inbound or outbound security rules in NSG. In this case, you could add an inbound security rule to backlist your clients' IP.
Refer to DOC, Note:
Network Security Groups (NSGs) are supported on the application
gateway subnet with the following restrictions:
Exceptions must be put in for incoming traffic on ports 65503-65534
for the Application Gateway v1 SKU and ports 65200 - 65535 for the v2
SKU. This port-range is required for Azure infrastructure
communication. They are protected (locked down) by Azure certificates.
Without proper certificates, external entities, including the
customers of those gateways, will not be able to initiate any changes
on those endpoints.
Outbound internet connectivity can't be blocked.
Traffic from the AzureLoadBalancer tag must be allowed.
Hope this helps.
When I try to execute New-AzureRmApplicationGatewayIPConfiguration to create an application gateway, I get an exception:
Subnet xxx cannot be used for application gateway yyy since subnet is not empty.
I encountered this error when I tried to add the application gateway to the same subnet as the backend servers.
Why is this not an option? Does each gateway require a separate subnet? What is the recommended configuration?
Related questions:
The documentation says backend servers can be added when they belong to the virtual network subnet. How can a back-end server belong to the virtual network subnet of the application gateway if the application gateway must be in a separate subnet?
How can the application gateway be configured without requiring a public IP address on the backend servers?
The application gateway must be in a subnet by itself as explained in the documentation, hence the reason it is not an option. Create a smaller address space for your application gateway subnet (CIDR 'x.x.x.x/29') so you're not wasting IP addresses unnecessarily.
It's a good practice to strive for a multi-tier network topology using subnets. This enables you to define routes and network security groups (ie: allow port 80 ingress, deny port 80 egress, deny RDP, etc.) to control traffic flow for the resources in the subnet. The routing and security group requirements for a gateway are generally going to be different than routing and security group requirements of other resources in the virtual network.
I had the same issue, so my virtual network was 10.0.0.0/24 which was not allowing me to create a separate subnet. I solved the issue as we added another address space into the azure virtual network e.g. 10.10.0.0.24, then created a new subnet so that the application gateway was happy to work with the backend servers.