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I have an App Service (currently under development so no heavy traffic) on Azure. It connects to a Google Cloud DB. Yesterday for no apparent reason, the Outbound IP addresses of the App Service all changed causing the connection between Azure and Google to fall over.

We haven't scaled the app or made any large configuration changes.

I'm just wondering for what reason(s) the Outbound IP addresses might change on Azure with seemingly no warning? Has anyone experienced this?

Thanks for any insight.

Update

Just to clarify - I am aware of the range of IPs (accessible via the App Serivce > Properties > Outbound IP Addresses) but in this case they ALL changed without notice.

scgough
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1 Answers1

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Azure App Service does not support fixed outbound IP due to its architecture considerations, instead, you have a range of IPs that could be used. To see the list of these IPs:

  1. select your app service
  2. navigate to properties
  3. verify the list of outbound IPs in "OUTBOUND IP ADDRESSES"

Note that you also get an external IP address if you configure a Custom Domain, but this is related to INBOUND connections only.

If you want your own set of outbound IPs or really need a fixed one, consider App Service Environment.

Update:

Are these outbound IPs guaranteed to remain the same as long as the azure web site isn’t deleted?

there is no guarantee, but they will not change from 1 day to the next, nor is there any plan or real need to change them. I have read that if this ever happens those impacted will get enough warning to make any changes to their systems to prevent any problems. They are never expected to change and you should feel comfortable that they will remain static.

https://blogs.msdn.microsoft.com/benjaminperkins/2016/03/02/how-to-find-you-outgoing-azure-app-service-ip-address/

Static Outbound IP without ASE - Still Under Review

https://feedback.azure.com/forums/169385-web-apps-formerly-websites/suggestions/16790656-add-static-ip-address-for-outbound-traffic-without

Bruno Faria
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  • Hi Bruno, Thanks for this. I know of the range of outbound IPs but perhaps I should clarify - they ALL changed. – scgough Nov 16 '16 at 13:47
  • I've updated the answer to reflect Microsoft statement on this. Benjamin is one of the engineers working with App Service. – Bruno Faria Nov 16 '16 at 14:03
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    Also, other references like azure feedback portal imply these are really not guaranteed to remain the same and the only way to achieve that would be using ASE. Latest reply about this topic: https://feedback.azure.com/forums/169385-web-apps-formerly-websites/suggestions/16790656-add-static-ip-address-for-outbound-traffic-without – Bruno Faria Nov 16 '16 at 14:15
  • What if I want to change the IP, is there any way to force a new IP – rollsch Apr 26 '18 at 02:50