Whats the strategy for IP address when setting up ILB? It makes sense to have a static IP but when would you want Dynamic?
When you create an internal load balancer on Azure, you will associate a virtual network and subnet with this load balancer. If you do not know which specific IP address you will use it as the frontend IP of the load balancer, you can choose Dynamic, then Azure will assign the next available unassigned or unreserved IP address in the associated subnet's address range. Also, you can change it to static after you have created your load balancer. If you want to specify a dedicated or known IP in the subnet at the first time, you could select IP address assignment static.
Read more about Private IP addresses.
Bottom-Line.
If you have an Azure environment behind a load balance you might want Frontend IP to be static so you are rest assured that you environment's public IP will not accidentally change except you want it to, especially if you are making use of SNAT.
Also you do not really save by making it dynamic, if there is a resource behind it you will have an IP charge for the whole month.
Related
Are Azure public IPs truly static or can they change?
I have 2 load balancers each have 2 VMs behind them.
I offer a multi-tenant SAAS solution to my end users and ask that they map a CNAME record in their DNS to our domain name. www.ourDomain.com
There are some scenarios where i would allow the end user to map an A record to our IPs. How risky is this with Azure IPs?
In fact, whatever basic or standard load balancer you are using, both are supporting to assign the public-facing load balancing solution with the static allocation method.
For basic SKU LB, you can change the basic public IP from the dynamic allocation method to static, for standard SKU LB, Azure always uses static allocation method for your standard public IP.
So there is no risk unless you are assigning the public IP to other resources or release these public IPs. For more details, you can look at this.
Static addresses are only released if a network interface is deleted.
If you change the allocation method to dynamic, Azure dynamically
assigns the previously assigned static IP address as the dynamic
address, even if the address isn't the next available address in the
subnet's address range. The address also changes if the network
interface is assigned to a different subnet within the same virtual
network, but to assign the network interface to a different subnet,
you must first change the allocation method from static to dynamic.
Once you've assigned the network interface to a different subnet, you
can change the allocation method back to static, and assign an IP
address from the new subnet's address range.
If you change the setting to static ip in the load balancer , it should remain static until you change it again.
In which scenario can we use a dynamic public IP Address ? I cannot think of a scenario where i would want to expose a public IP for internet facing azure services but that could be dynamic.
The two scenarios we use dynamic IPs are
A VM has a mechanism to auto update a DNS A record with its new address.
The Ip address has a CNAME mapped to the DNS name - so mapping www.example.com to example.westus2.cloudapp.azure.com This way whenever the address changes it still points to the same thing.
Remember though that a dynamic IP address doesn't change unless the VM is deallocated. Or the underlying host fails and VM is started on another host.
Hope this helps- https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-ip-addresses-overview-arm
That outlines the use cases for both static and dynamic IPs.
The main use case for dynamic PIP's for me is for gateways. For web or app services I would use static.
A few days ago, the IP address of our VB Windows Server changed from 40.x.x.x to 13.x.x.x on the Azure platform. We have many loggers in the field that connect to this IP address and now, none of them can connect.
Can the IP change without any warning from Azure?
Also, there is no support to be found. No number, no online support... I mean, This is not a problem I should be paying support for... besides.. support is more expensive than the VM.
Your IP address will change if, for instance, you restart your virtual machine. However, you can set this to be static by doing so:
go to Public IP addresses
Click Configuration
Set assignment to Static
Click Save
This will retain the IP address that you have right now but at an additional cost.
Can the IP change without any warning from Azure?
For now, there is no warning when public IP address change. I think you should know IP address types and allocation methods in Azure.
There are two methods in which an IP address is allocated to a public IP resource - dynamic or static. The default allocation method is dynamic, where an IP address is not allocated at the time of its creation. Instead, the public IP address is allocated when you start (or create) the associated resource (like a VM or load balancer). The IP address is released when you stop (or delete) the resource. This causes the IP address to change when you stop and start a resource.
If you want to public IP address not change, you could change dynamic to static.
I have two VMs being load balanced by an external facing load balancer. I am able to successfully connect to those VM's from the internet through that LB rule.
However, I want to restrict access to that load balancer's public IP address (or more precisely - to the VM's behind it) to a specific source network. So that rather than the entire internet being able to access it, only specific public subnets could use it.
Looking in TCP connection tables on the VM's - it looks like the Azure LB is natting the source IP coming through it. So, my NSG's on the VM guests cannot filter on "SourceIP = Desired Source".
Is there any way to do this in the Resource Manager version of Azure?
The source port and address range are from the originating computer, not the load balancer.
From https://azure.microsoft.com/en-us/documentation/articles/virtual-networks-nsg/#design-considerations (look under "Load Balancers")
Similar to public facing load balancers, when you create NSGs to
filter traffic coming through an internal load balancer (ILB), you
need to understand that the source port and address range applied are
the ones from the computer originating the call, not the load
balancer. And the destination port and address range are related to
the computer receiving the traffic, not the load balancer.
I'm guessing it's using x-forwarded-for and that NSGs understand that. Connection tables don't. They're raw connections and as such show the NAT.
I have RM VNET and the address range is 192.168.3.0/24
I have 4 VM running on it without issue.
What I noticed here is I found the IP of the VM's get changed every alternate days and because of this the APP running on the VM's are affected.
For now I have assigned Static IP for the VM's. but need to change it to Dynamic as static IP is chargable
Is there any way to assign a static IP for the VM's without charges?
If this is referring to the free public IP assigned to you, one way to get around the cost is using a CNAME entry in your DNS pointing to your resource's FQDN. Set TTL as low as you can afford so the outside world can pick up the change fast.
Here is an article about how: http://www.codewrecks.com/blog/index.php/2015/10/11/where-is-my-dns-name-for-azure-vm-with-new-resource-manager/
If this is referring to VM's internal IP address such as 192.168.3.3, I don't believe static private IP address is chargeable.
Here is an solid article explain things:
https://azure.microsoft.com/en-us/documentation/articles/virtual-network-ip-addresses-overview-arm/