I'm working on a script to figure out which IPs are available for an Application Gateway if there are already Gateways in the subnet.
When I use Test-AzureRmPrivateIPAddressAvailability and test an IP address that's being used by the frontend of an Application Gateway, it still outputs Available. Should it be unavailable?
Not sure, but it seems that is a bug. The private IPs can associate to VM, Load Balancer and Application Gateway. And there should no difference that the availability shows. You can get more details about the Private IP Addresses.
I did the test that when a private IP address associated with the VM and Load Balancer, then the availability of the IP shows False. Except for the Application Gateway.
But don't worry, it does not affect the function of the Application Gateway and the virtual network. When a private IP associated with the Application Gateway and then Azure will disallow other Application Gateways use it( when the Application Gateway create in a subnet and then the subnet can only contains Application Gateway, see this ). Maybe this issue would be fixed in the future.
Hope this will help you.
Related
I have the following situation:
If I deploy an application (Deployment, Service and Ingress) in my kubernetes cluster, my ingress deployment is being automatically added to my application gateway (I am using the Azure Application Gateway Ingress Controller; https://azure.github.io/application-gateway-kubernetes-ingress/annotations/ ). So far so good.
That means that my application can be reached via my application gateway via https://my-app-gateway-public-ip/myAppPath/. Also, I have an additional private DNS zone which makes my app accessible via https://dns-name/myAppPath.
Additionally, we have an AADDS in combination with a Bastion Service. Deployed some virtual machines and the virtual machines use the DNS resolver of the AADDS (for authentication against the AAD).
The problem is: If I am outside of the cloud, I can nslookup the dns or can access the site via the ip, but I cannot do that with my virtual machines. My DNS server (within the AADDS) is unable to resolve the dns or accessing the ip. I am wondering what the issue is.
The bastion and AADDS are in different subscriptions and therefore different virtual networks. I established already a peering between those virtual networks (or the authentication between the AADDS and the VMs wouldn't work).
The kubernetes cluster and the application gateway are also in a different subscription, but no peering has been done so far.
Are there any hints what I could be missing?
Kind regards
• Since, you are using a Bastion gateway server to connect to the VMs hosted in your subscription, the Bastion gateway server must be having a public IP address through which then the registered underlying VMs can be connected to via private links created in the private DNS zones associated with a particular virtual network in a subnet and an assigned private IP address and a FQDN accordingly. Thus, if you want to access the application website hosted behind the application gateway, then you will have to create a conditional forwarder in the DNS zone in AADDS to redirect the internal requests from the VMs hosted within a virtual network to the public IP address of the website hosted behind the application gateway
• Thus, a conditional forwarder forwards the DNS resolution requests for a particular resource hosted on the public internet for which the DNS host resolution is not found or done in that DNS zone which usually serves or fulfils the requests related to internal environment. As a result, when a VM configured with a private IP is registered as a host in the internal DNS zone queries the public IP or FQDN associated with the application’s website, the DNS requests are forwarded to the public internet through the conditional forwarder and then the results are displayed in the VM’s browser for the application’s webpage. Thus, the VMs don’t need to have internet access but the DNS server should have or should forward the requests through the Internet proxy server accordingly to reach the internet.
For more information on creating conditional forwarder in AADDS, kindly refer to the below link: -
https://learn.microsoft.com/en-us/azure/active-directory-domain-services/manage-dns#create-conditional-forwarders
I have created one Web app on Azure portal and its integrated with subnet under specific VNET.
Now, when I am trying to do telnet to one of my organisation's internal relay server IP from my web app its not getting connected. The request is going from web app's APIPA address range not from subnet's address range. I checked the IP as well of the web app using ifconfig and I found out that its taking from APIPA address range not from subnet one.
Any idea what steps do I need to take so that web app will take IP from subnet address range of the VNET not from APIPA address range.
Thanks in advance.
After my validation, when the app service on Linux is integrated with a virtual network. There is an extra NIC binding to the app service. It's IP address from APIPA address range. It looks like a design behavior as the app service on Linux is running in a standard Docker Container, read here. Also, for a normal app service is a multi-tenant environment, you can not get a dedicated IP address unless you are using a dedicated environment---ASE, read here.
Furthermore, from how regional VNet Integration works, you will see the app service integrated with a vNet is not the same as a VM from a VNet.
Regional VNet Integration works by mounting virtual interfaces with
addresses in the delegated subnet. Because the from address is in your
VNet, it can access most things in or through your VNet like a VM in
your VNet would. The networking implementation is different than
running a VM in your VNet. That's why some networking features aren't
yet available for this feature.
In this case, if you wan assign a private IP address for app service, you can use Azure Private Endpoint with web apps(Preview). Read this blog for more details.
Azure Private Endpoint provides private IP address access by using a
network interface controller (NIC) attached to a virtual network
subnet for an Azure web app, allowing access from an on-premise VPN or
ExpressRoute. Implementing an endpoint effectively blocks the public
inbound access. This technology is very similar to an internal App
Service Environment (ASE) but much cheaper.
I'm trying to deploy my application on Azure. Currently, I have an application gateway deployed in one subnet s1, and in the backend pool I have Linux VMs. As per the requirement, I cannot use any public ip so, I'm using only private ip on Application Gateway. Since we need the internet connection at the time of deploying application, I tried attaching NSG to the Application Gateway's subnet with inbound "Internet" allowed. When I attached the NSG to application gateway subnet, the backend health showed as unhealthy with error:
"Cannot connect to server. Check whether any NSG/UDR/Firewall is blocking access to server. Check if application is running on correct port."
I tried to add rules specified in MSFT's document https://learn.microsoft.com/en-us/azure/application-gateway/configuration-overview#allow-application-gateway-access-to-a-few-source-ips but its not helpful. So my questions are:
Is there anything more I need to add to NSG on application gateway's subnet.
Is it a good strategy to allow internet access using the inbound rule on NSG? (Inbound rule -> service tag -> Internet). Is there any other way I can have internet access just at the time of deployment? PS: I'm not allowed to use public IP at all.
Many thanks!
You can deploy Application Gateway with Public IP and Private IP. All you need to do is to create the listener with the private Frontend IP and leave the Public IP as such.
Since Public IP is not attached with any of the listener, no one will be able to access your site from Internet via Public IP of your Application Gateway.
When AppGW needs to initiate outbound to Internet, it uses that Public IP.
Note: You cannot have only Private IP as Frontend in V2 deployment and you can deploy Application Gateway with only Private Frontend IP in V1 SKU.
I am little but puzzled by Azure Network Analytics! Can someone help resolving this mystery?
My Kubernetes cluster in Azure is private. It's joined to a vNET and there is no public ip exposed anywhere. Service is configured with internal load balancer. Application gateway calls the internal load balancer. NSG blocks all inbound traffics from internet to app gateway. Only trusted NAT ips are allowed at the NSG.
Question is- I am seeing lot of internet traffic coming to aks on the vNET. They are denied of course! I don't have this public ip 40.117.133.149 anywhere in the subscription. So, how are these requests coming to aks?
You can try calling app gateway from internet and you would not get any response! http://23.100.30.223/api/customer/FindAllCountryProvinceCities?country=United%20States&state=Washington
You would get successful response if you call the Azure Function- https://afa-aspnet4you.azurewebsites.net/api/aks/api/customer/FindAllCountryProvinceCities?country=United%20States&state=Washington
Its possible because of following nsg rules!
Thank you for taking time to answer my query.
In response to #CharlesXu, I am sharing little more on the aks networking. Aks network is made of few address spaces-
Also, there is no public ip assigned to any of the two nodes in the cluster. Only private ip is assigned to vm node. Here is an example of node-0-
I don't understand why I am seeing inbound requests to 40.117.133.149 within my cluster!
After searching all the settings and activity logs, I finally found answer to the mystery IP! A load balancer with external ip was auto created as part of nginx ingress service when I restarted the VMs. NSG was updated automatically to allow internet traffic to port 80/443. I manually deleted the public load balancer along with IP but the bad actors were still calling the IP with a different ports which are denied by default inbound nsg rule.
To reproduce, I removed the public load balancer again along with public ip. Azure aks recreated once I restarted the VMs in the cluster! It's like cat and mouse game!
I think we can update the ingress service annotation to specify service.beta.kubernetes.io/azure-load-balancer-internal: "true". Don't know why Microsoft decided to auto provision public load balancer in the cluster. It's a risk and Microsoft should correct the behavior by creating internal load balancer.
App Service IP Restriction for Application Gateway with WAF
I want to setup Application Gateway WAF in front of multi-tenant (non-ASE) App Service Web Apps.
I know this is possible now, according to official document.
For security, inbound traffic to Web Apps should be restricted to only allow requests for connection the application gateway Public IP. But I couldn't find the way to do it.
Idea 1. Using VNet integration:
It's not possible to using "App Service Vnet Integration" cause it's not possible to specify App gateway's VNet.
Moreover, in my understanding, VNet integration can't restrict inbound traffic.
Idea 2. Using IP Restriction config of App Service:
Application Gateway's Public IP Address can be configured as Dynamic one, Static IP Address can't be chosen.
So, I think it's not possible to specify Application Gateway's Public IP Address to IP Restriction config of App Service, cause configured IP is static but actual IP can be changed.
Any good idea?
The Application gateway IP address can change if the gateway is stopped and started by the customer.
So if you have not stop and start the application gateway, the IP address will not change.