Check if an NSG is blocking a port

Question

_{Wednesday, April 4, 2018 9:52 AM}

Hello,

We have a server in Azure and can't connect through on a port, I've added a rule and I'm told the port is open on the App within the VM.  Is there a log that can tell me if the port is being blocked by the NSG or if another port is being used and blocked?

Thanks

All replies (4)

_{Wednesday, April 4, 2018 11:05 AM ✅Answered}

The best tool to use for this is Flow Loggin, part of the Azure Network Watcher tool. This will show you where traffic is being allowed and blocked. Have a read of this article to get started.

Sam Cogan Microsoft Azure MVP
Blog | Twitter

_{Wednesday, April 4, 2018 11:18 AM}

Adding to Sam’s suggestions. To analyze and troubleshoot the VM traffic flow, I suggest you refer the suggestions outlined in this document Using Effective Security Rules to troubleshoot VM traffic flow and see if that helps.

Also, refer the steps outlined in this document Troubleshoot access to an application running on a Windows virtual machine in Azure to further isolate the application access issue and do let us know what specific port you are referring to.

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_{Wednesday, April 4, 2018 6:18 PM}

I used "IP Flow Verify" in the end and it was ready helpful.

_{Thursday, April 5, 2018 6:06 AM}

Thanks for the update. Glad to know the ‘IP Flow Verify’ helped.

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