Can't access Frontend IP of load balancer externally and diagnostics says ports 80,30025,and40025 are being blocked but no block is in place.

Question

We are trying to deploy Jscape MFT Gateway on a Windows Server 2016 vm. We have put it behind a load balancer. However, we can not access the public IP and when we run diagnostics, it says that ports 80, 30025, and 40025 are blocked. But there are no deny rules for any of these ports. However, on the VM they don't show these ports are open and listening even though we've explicitly opened them.

What are some areas that may be blocking this connection that we are missing.

Answer 1

@Chris Porter

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

I understand that you have configured your backend (Jscape MFT Gateway on a Windows Server 2016 vm) to be a part of load balancer.

I suggested if you could please share more details about the configuration of the Load Balancer:

• Please note that the ports of a Load Balancer are by default blocked.
• You have to explicitly create Load Balancer rules to map a frontend IP configuration and port to a backend Pool's Port
• Only then, will Load Balancer start forwarding traffic in that Port.
• Also, your Backend VM must be listening on the port you configure on the Load Balancing rule, or else, Load Balancer will mark it unhealthy and will not forward traffic.
  • Refer : Azure Load Balancer health probes

You informed us that the configuration was indeed correct, however, the application was not listening on the Ports.

Post making some configurational changes in the application, you confirmed the issue to be resolved.

Thanks,

Kapil

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