PortQry to check if server is accpting the traffic; Use Case: AWS Machines Unable to Access an Application Link

 

The use case was AWS machines were not able to open a link. We had to request Network Firewall team to enable few subnets and whitelisted to access the link. 

Here’s a corrected, clear, and blog‑ready version with professional flow and concise explanation:

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Use Case: AWS Machines Unable to Access an Application Link

In this use case, AWS-hosted machines were unable to open a required application link. Initial investigation showed that the application itself was available, but requests from the AWS environment were not reaching the target server.

The issue was identified as a network firewall restriction. The Network/Firewall team was engaged, and specific AWS subnets were enabled and whitelisted to allow outbound access to the application URL. Once the firewall rules were updated, connectivity was restored.

To validate connectivity during troubleshooting, PortQry was used to check whether the target server was accepting traffic on the required port.

PortQry Usage

PortQry is a command-line utility used to verify network connectivity to a specific server and port.

Purpose:

• Confirm whether the target server is reachable
• Identify whether traffic is allowed, blocked, or filtered by a firewall

Example:

portqry.exe -n <target-server> -e <port> -p TCP

If the result shows FILTERED, it typically indicates that a firewall or network security device is blocking the traffic, confirming the need for Network/Firewall team intervention.