Azure inbound TCP port rules don't work (with minor exceptions)

Attila Gulyas 96 Reputation points
2021-08-13T23:16:02.833+00:00

This issue has been mentioned so many times (or variants of it; e.g. port resets itself over time), but none if this works with new Ubuntu Server 20.04 VM for me.

Trying to open TCP ports 80 and 443, but the only one that gets opened is TCP 22 that was specified during creation. None of the following workarounds work:

  • delete and re-create rule with same values
  • dissociate/associate NSG
  • create new NSG with exact same value, dissociate original NSG, and associate the new one

Waited at least 30 mins after each workaround, no joy. I also don't think that rule propagation is the issue, because if I enable ICMP, then pinging works immediately.

Azure Virtual Network
Azure Virtual Network
An Azure networking service that is used to provision private networks and optionally to connect to on-premises datacenters.
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  1. Attila Gulyas 96 Reputation points
    2021-08-13T23:48:21.863+00:00

    Alright, I am/was an idiot. Kept getting

    $ nc -zv 1.2.3.4 80
    nc: connect to 1.2.3.4 port 80 (tcp) failed: Connection refused
    
    $ nc -zv 1.2.3.4 443
    nc: connect to 1.2.3.4 port 443 (tcp) failed: Connection refused
    

    but that just means that nothing is listening on the server side; if the rules would block, there would be no output, and netcat would seemingly just hang.

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