Question

I recently deployed an Azure app to the staging environment which is supposed to accept TCP packets in port 2993. When run in the Azure emulator, it does this very well, and performs exactly as it should.

However, now that it is on Azure’s staging servers, whenever I try to connect to the TCP port, i get the following SocketException:

A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

My web app has two instances, one is a worker role (it has 2993 configured in its endpoints) and a web role (only for port 80). Port 80, by the way, functions perfectly. The web app was created with Visual Studio in C#. Why is this happening and how can I fix it?

All help is greatly appreciated.

Answer 1

I would like to explain what was the issue and why adding above code solve this problem for others benefit.

In your worker role, you configure any TCP endpoint along with any port number. When this VM starts the VM is provisioned to use this port and firewall is included an exception to provide access to this port. By the time your is ready to start your Azure VM already have TCP/IP address and configured port is enabled.

Now when your role starts and if you have any service or application required access this port you really need to l

For example If I have Tomcat/Java configured in my worker role, I must have to create a TCP listener on my configured port. This can be done when my worker role starts as below:

1. Get the IP address and Port number of the current role instance
2. Create a TCP Listener and start on this IP address and Port
3. Add the code to perform step 1) and 2) in my worker role OnStart() function.

The code will look like as below:

TcpListener TomcatPortListener = new  TcpListener(RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["TomcatWeb80"].IPEndpoint);
TomcatPortListener.Start();

In your case you you did exactly the same you got the IP address and Port number from and then created an endpoint from a socket address using IP/Port:

RoleInstanceEndpoint externalEndPoint = RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["TCPin"];
IPEndPoint localEndPoint = new IPEndPoint(externalEndPoint.IPEndpoint.Address, externalEndPoint.IPEndpoint.Port);
localEndPoint.Create();

It is a must setting for any web or worker role which create TCP endpoint.