KOSD, or Kopi-O Siew Dai, is a type of Singapore coffee that I enjoy. It is basically a cup of coffee with a little bit of sugar. This series is meant to blog about technical knowledge that I gained while having a small cup of Kopi-O Siew Dai.
It is a common scenario for developers to integrate with different parties by using their APIs. Most of the time, the APIs are located in a locked-down network environment where only whitelisted IP addresses are allowed to access their APIs. We will then be asked to give the API providers the IP addresses of our servers.
If it’s our web back-end calling the APIs and we host our web applications on Microsoft Azure App Services, then how could we get the IP addresses?
As mentioned in a discussion about inbound IP address by Benjamin Perkins, the Escalation Engineer on the Azure team, there are about 4 outgoing IP addresses for an Azure Web Apps normally. To retrieve the outbound IP addresses of an Azure web app, we simply need to get it from the Properties of the web app on Azure Portal.
We can also get the same result if we use the Azure Resource Explorer which is still in preview now. Benjamin covered this in a video clip on his article too.
For PowerShell lovers, as pointed out by Adrian Calinescu, one of the commenters on Benjamin’s article, we can use PowerShell to find out the outbound IP addresses too. With the new Azure Cloud Shell, we can simply use the following command to retrieve directly the outbound IP addresses of an Azure web app on Azure Portal directly.
Get-AzureRmResource -ResourceGroupName -ResourceType Microsoft.Web/sites -ResourceName | select -expand Properties | Select-Object outboundIpAddresses
For those who would like to have your own set of outbound IP addresses, please check out ASE (App Service Environment) which grants users control over inbound and outbound application network traffic.
Finally, we can also whitelist all the IP addresses of the Azure datacentres, which can be downloaded here.
cuteprogramming 