Der Azure Networking Experts,
Our WebApps are frequently running out of outbound TCP connections. Most of the outbound connections are actually Azure-internal connections (SQL, BlobStore, Backend Services). But we don't have Virtual Network and Private Endpoints in place yet.
Could Virtual Network and Private Endpoints help solve our issue? I'd expect that by using internal IP addresses, there's no SNAT IP matching required at all?
I'm unfortunately no expert in networking, but I'm looking at this issue from WebApp-Developer perspective.. (the recommendations for how to save connections, like keepalive etc. are just not enough to fix the issue).. Any advice appreciated, however, we definietly prefer to use managed Azure services like auto-scalable WebApp farms.
SNAT is used when you route outbound traffic through a public load balancer. App service plans are provisioned with public IP addresses and would not need SNAT out of the box.
App service plans support vNet integration and can accesses other resources on their private IP addresses if the vnet peering is correctly configured.
Q: Could Virtual Network and Private Endpoints help solve our issue?
A: Yes, it would be a matter of configuring the vnet integration on the App Service plans and configuring private end points on the other azure resources. One might also look to utilize the public IPs of the services rather than putting things behind a load balancer.
Q: I'd expect that by using internal IP addresses, there's no SNAT IP matching required at all?
A: Yes, you should not need any SNAT IP matching.
Related
I have several machines in a backend pool associated with an internal load balancer. However, they currently do not have outbound access. The documentation seems to indicate that I should be able to create a public load balancer and attach the same backend pool with it so that I can have outbound access from those machines. However, when I create a public load balancer, I don't have the option of associating it with an existing pool, and when I try to create a new backend pool for the public LB I can't associate those machines with it. Neither machine has a public IP address. From the dashboard it shows:
where all the interesting info is cut off. What am I missing?
Even VM's in the backend pool of an ILB should have a default outbound IP. If you don't have outbound access have you checked the security group rules to make sure outbound traffic is allowed?
I'm afraid you can't do this on the same LB for both inbound & outbound traffic.
If you happen to use the Basic SKU, VMs behind the LB have internet
access as outbound connections are NAT'ed by Azure. But, all VMs have to be in the same AZ. This wasn't a great idea & we declined it
If you use a Standard SKU, outbound connections to the internet are not possible. We learned this after many failed & painful attempts. More details here
As discussed in the above link, attaching a public IP to each VM nic isn't a good idea either
What worked for us is to create another LoadBalancer specifically for outbound connections, attach public IP to that LB & configure outbound rules. More details here
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'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.
I have a case where I want to migrate on-prem servers to Azure, but I should still have the local IPs pointing to these VMs. I mean by the local IPs the country-range of IPs since these VMs should be accessed using country IPs for regulatory reasons.
I heard that this is possible, but I have no idea what type of resources I should use to allow this, VNET, VPN, ExpressRoute ?? And how to do it as I have no experience in networking what so ever.
Regards,
NAT is a method of remapping one IP address space into another by modifying network address information in Internet Protocol (IP) datagram packet headers while they are in transit across a traffic routing device.
You can setup a site-to-site VPN between on-prem and Azure Vnet, then deploy a server on-prem run as the NAT device.
It is possible, but with some complications and constraints:
You can run these servers/VMs in Azure using their public IP addresses. You need to create the Virtual Network using these address ranges, but it is possible. The catch here is that these public IP addresses are only accessible via cross premises connectivity solutions such as Azure VPN gateway or Azure ExpressRoute. You cannon access these VMs using their "public" IP addresses directly over the Internet. For this purpose, these public IP address ranges are really treated as "private addresses".
Once you create the virtual network with the public IP addresses (as private address space) in Azure, you will also need to make sure your routing in the on premises network is configured correctly to forward the traffic to these VMs over the VPN tunnels or MPLS/WAN network if you are using ExpressRoute.
If these servers/VMs need to accept requests directly from the Internet, the traffic from the Internet will still come to your on premises network because that's where your ISPs will direct the traffic. You will need to ensure these traffic will be routed correctly over the cross premises connectivity (VPN/ExpressRoute) to Azure.
Hope this helps a bit. Please let me know if this answers your question.
Thanks,
Yushun [MSFT]
I am building an cloud infrastructure on AWS.
I have some backend applications (like database servers) and other front end app (like webservers) that needs ingoing/outgoing traffic.
I also have some devops/dev app like Jenkins, and Airlfow (a workflow management tahts has a web UI) that i need to protect. Some of these apps, like Airflow, doesn't have security mechanism (for example login/password). And I still need access it on 80 port from Internet.
I was thinking to setup a AWS VPC, with a private subnet and public subnet. In the public subnet I will put the fron end apps and the private subnet I will put the backend services (like databases).
For the backend services, I need a way to my dev team to connect, for example, in a MySQL database (port: 3306).
What is the correct way of do this?
I need to expose port 3306?
Do I need a NAT or a bastion host? What is the difference between them?
If I setup a NAT/Bastion hosti will make a port foward rigth? If I have two instances of a mysql database, how can I connect to each other using the bastion? I need to allocate different ports on bastion and make the port foward?
For the devops/dev app:
Which subnet do I choose?
If i put on the private subnet, how can my team access it on 80 port?
Do i need a intranet/vpc foo this applications?
These are all quite common problems people are faced with on AWS. You have lots of options.
You could put all of your backend and dev opps services in the private subnet. You then have a number of choices to connect to them securely.
Option 1
Use Security Groups to limit access to these nodes. You can use Security groups to only allow specific IP addresses to connect to your resources.
Option 2
Use a bastion host.
Referring to your question "What is the difference NAT and bastion host?".
NAT simply allows instance inside a private subnet to connect to the internet by routing all their traffic through the NAT instance. The NAT instance then directs the return traffic from the internet back to the correct nodes in the private subnet. NAT alone does not allow you to connect to instances inside your private subnet from the outside, you'd need to combine it with Port Address Translation to achieve this.
A Bastion host is an instance that you place in a public subnet of your VPC. You can therefore connect to it from the internet. Once you're connected to your Bastion host, you can connect to any other instance inside your VPC using the private IP. Once you ensure maximum security to your bastion host, you're in business.
As a result, you could use a bastion host to connect to all those special nodes in your private subnet.
Option 3
Set up a VPN connection to your VPC using the built in functionality in VPC or setting up a VPN instance with something like OpenSwan running on it.
VPN connections are extremely secure but can often be a tad temperamental (*personal opinion from personal experience).
So, you have lots of choices. I'd recommend doing a few more google searches and digging deeper into the AWS docs as these are all commonly asked questions!
Good luck! :)