I have a very simple Azure VM setup. One VM is behind an Internal Load Balancer, and it's private IP address is 10.0.1.10.
A Web Service is running in that VM. I can access website by using http://localhost, but as per my software requirement, I have to use Load Balancer private IP address instead of localhost. But I can not browse with Internal Load Balancer IP address (http://10.0.1.10 does not work from that VM).
Is that by design that I can't access Internal Load Balancer by it's private IP address? Or I need to do something special to make it work?
There's a difference between public and internal Azure Load Balancer configurations.
When Azure Load Balancer is used in a public load balancer configuration, SNAT is used for outbound requests. This means a VM behind a public can reach the public IP address of the load balancer and the flow will be load balanced accordingly. This will consume an ephemeral port for each connection to the VIP.
Internal load balancer configurations do not offer SNAT today. In turn, an internal load balancer configuration does not allow a pool member to access the IP address of the internal load balancer.
We are looking at addressing this in a future release by allowing an option to enable SNAT for internal load balancers as well. Mandatory SNAT can actually impose constraints for those who don't need to access the IP address of the load balancer, and therefore this needs to be an option rather than the default.
According to your description, do you means that the VM in the load balancer and the web service running on the VM, you want to use the VM to browse the internal load balancer IP, but it doesn’t work.
I had test in my lab, and the same error occurred. By the way, the load balancer can’t work in this way.
Here is my network capture result:
Maybe we should to create a new VM outside of the load balancer, then you can browse the load balancer IP. Because once a network interface is added to a load balancer's back-end IP address pool, the load balancer is able to send load-balanced network traffic based on the load-balanced rules that are created.
If you still have questions, welcome to post back here. Thanks.
Best Regards,
Related
Please can someone advise how to restrict access on port 80/443 to some Azure VMs, so that they can only be access via the public IP Address that is associated to an Azure Load Balancer.
Our current setup has load balancing rules passing through traffic from public IP on 80=>80 and 443=>443, to back end pool of 2 VMs. We have health probe setup on port 80. Session persistence is set to client IP and floating IP is disabled.
I thought the answer was to deny access (via Network Security Group) to internet (service tag) on 80/443. Then add rule to allow service tag (AzureLoadBalancer) on the same ports. But that didnt seem to have an effect. Having read up a little more on this, it seems the AzureLoadBalancer tag is only to allow the health probe access and not specifically inbound traffic from that load balancer.
I have also tried adding rules to allow the public IP address of the load balancer, but again no effect.
I was wondering if I need to start looking into Azure Firewalls? and somehow restrict access
to inbound traffic that comes through that?
The only way I can get the VMs to respond on those ports is to add rules to allowing 80/443 from any to any....
After reading your question, my understanding is that you have a Public load balancer and the backend VMs also have instance level Public IPs associated with them and hence direct inbound access to the VMs is possible. But you would like to make sure that the direct inbound access to VMs is restricted only via the load balancer.
The simple solution for you to achieve this is by disassociating the instance level public IP of the VMs, this will make the LB public IP as the only point of contact for your VMs.
Keep in mind that the LB is not a proxy, it is just a layer 4 resource to forward traffic, therefore, your backend VM will still see source IP of the clients and not the LB IP, hence, you will still need to allow the traffic at the NSGs level using as source "Any".
However, if your requirement is to enable outbound connectivity from Azure VMs while avoiding SNAT exhaustion, I would advise you to create NAT Gateway, where you can assign multiple Public IP address for SNAT and remove the Public IP from the VM. This setup will make sure that the inbound access is provided by the Public load balancer only and the outbound access is provided by the NAT gateway as shown below:
Refer : https://learn.microsoft.com/en-us/azure/virtual-network/nat-gateway/nat-gateway-resource#nat-and-vm-with-standard-public-load-balancer
https://learn.microsoft.com/en-us/azure/virtual-network/nat-gateway/tutorial-nat-gateway-load-balancer-public-portal
You could also configure port forwarding in Azure Load Balancer for the RDP/SSH connections to individual instances.
Refer : https://learn.microsoft.com/en-us/azure/load-balancer/manage#-add-an-inbound-nat-rule
https://learn.microsoft.com/en-us/azure/load-balancer/tutorial-load-balancer-port-forwarding-portal
I want to run my application with AKS cluster(version - 1.18.14) with the dependency of standard load balancer to create multiple node pools. But, the standard load balancer is creating public IP address. which is not suitable for my application. Because my application is private not public.
Is there any way to "create Standard load balancer without public IP address in Azure?"
Thanks.
Actually, when you create the AKS, it creates a public IP as the outbound IP address for the Load Balancer, and it's for the egress. So it does not affect that your application is private or public. Instead, what you need to focus on is inbound, if your application is private, you just need to use the internal Load Balancer, I think this is what you are looking for.
I have created a internal load balancer in azure and backend pool configured two vm's health probe and rule also configured, If I browse the Load balance ip it work fine but while i'm checking the ping request from the VM to Load balancer it shows time out error. Is it possible to make a successful ping request.
Regular icmp traffic is not allowed on Azure load balancers, you should either try a port ping (psping), telnet, nmap, nc, or other utilities to check E2E connectivity.
Some extra details here:
https://social.msdn.microsoft.com/forums/azure/en-US/e9e53e84-a978-46f5-a657-f31da7e4bbe1/icmp-outbound-ping-on-azure-vm
Not only ICMP, any traffic from backend VM to frontend IP of internal load balancer will not work. This is one of the limitation of azure internal load balancer.
Bhuvanesh Kumar Kumaresan, Cloud Solution Architect
I have a VNET with a subnet, there are 3 VMs in the subnet, the VNET is connected via a VPN connection to an on-premises server. The on-premises server will send requests to an internal IP of the subnet.
What I'd like to do is host a load balancer with no public IP, but has an IP in the subnet range. The on-premises app would then talk to the single load balancer, which would in turn forward the request on to any of the servers hosting my app in the subnet.
Can anyone tell me if this is possible, or an alternative if possible.
I believe you are looking for an internal load balancer.
You can find documentation for that here: https://learn.microsoft.com/en-us/azure/load-balancer/load-balancer-get-started-ilb-arm-portal.
Azure Internal Load Balancer (ILB) provides network load balancing between virtual machines that reside inside a cloud service or a virtual network with a regional scope.
Create a Load Balancer as usual, but specify Type: Internal.
Probably best to make it use a static IP address as well so it won't change.
Then you'll need to configure its back-end pool and health probe so it knows where to route traffic.
How can virtual machines behind an Azure internal load balancer access internet? Is there an AWS NAT gateway equivalent in Azure?
A Virtual Machine that is part of the backend pool of a Standard (not Basic) Internal Load Balancer can not make outgoing connections to the Internet.
To make outgoing connections it is necessary to create a second Load Balancer with a public IP with the same backend pool and a dummy rule with a dummy probe. Once the rule is created then it will trigger the creation of an outbound SNAT.
https://learn.microsoft.com/en-us/azure/load-balancer/load-balancer-outbound-connections#defaultsnat
By default, Azure VM behind an Azure internal load balancer, that VM can access the internet, but you can't access it from internet.
If you want to access it, you can create a VM in that VM with a public IP address, use that VM work as jumpbox. Also you can assign a public IP address to that VM, then use that public IP address to access it.