Lesson Learned #261: Java vs Permission denied: connect

Today, I worked on a service request that our customer got the following error message using Java code: 

Exception in thread "main" com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host servername.database.windows.net, port 1433 has failed. Error: "Permission denied: connect. Verify the connect
ion properties. Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port. Make sure that TCP connections to the port are not blocked by a firewall."

or 

"Exception in thread "main" com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host nodename.tenantring.northeurope1-a.worker.database.windows.net (redirected from servername.database.windows.
net), port 11001 has failed. Error: "Permission denied: connect. Verify the connection properties. Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port. Make sure that TCP connections to the port are not blocked by a firewall.". at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:234)
at com.microsoft.sqlserver.jdbc.SQLServerException.ConvertConnectExceptionToSQLServerException(SQLServerException.java:285)
at com.microsoft.sqlserver.jdbc.SocketFinder.findSocket(IOBuffer.java:2462)
at com.microsoft.sqlserver.jdbc.TDSChannel.open(IOBuffer.java:668)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:2695)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:2362)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectInternal(SQLServerConnection.java:2213)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:1276)
at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:861)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)"

I would like to share with you what was my lessons learned here.

The first thing is to isolate the problem running the suggested Java code to see the results:

package testconnectionms;

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.lang.model.util.ElementScanner6;
import javax.sql.DataSource;

/**
 * Simple connection test.
 *
 */
public class SQLTest
{
	static {
		try {
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
		} catch (Exception ex) {
			System.err.println("Unable to load JDBC driver");
			ex.printStackTrace();
			System.exit(1);
		}
	}

	public static void main(String[] args)
		throws SQLException
	{
		String username   = "username";
		String password   = "Password";
		String envname    = "env";
		String seconds   = "10";
		        
		System.out.println("Arguements are: username="+username+",password="+password+",envname="+envname+",seconds="+seconds);
		
		String url = String.format("jdbc:sqlserver://servername.database.windows.net:1433;database=dbname;sslProtocol=TLSv1.2", envname,envname);

		System.out.println("-- Connecting to " + url);
		
		long start = System.currentTimeMillis();
		Connection connection = DriverManager.getConnection(url, username, password);

		if (false) {
			
		}
		
		final long time1 = System.currentTimeMillis();
		long time2 = time1;
		long cnt = 0;
		Integer secInt = Integer.valueOf(seconds);

        PreparedStatement st = connection.prepareStatement("SELECT * from demo");
		st.setQueryTimeout(20);
		while (time1 + (secInt.intValue() * 1000) >= time2)
		{
			cnt++;
			
			
			ResultSet rs = st.executeQuery();
			rs.next();
			rs.close();
			
			
			time2 = System.currentTimeMillis();
		}
		st.close();
		
		Long statementsCount = Long.valueOf(cnt);
		Long statementsPerSecond = Long.valueOf(cnt / ((time2 - time1) / 1000));
		Double timePerStatement = Double.valueOf(1000.0 / (cnt / ((time2 - time1) / 1000.0)));
		
		System.out.println("statementsCount="+statementsCount);
		System.out.println("statementsPerSecond="+statementsPerSecond);
		System.out.println("timePerStatement="+timePerStatement);
	}
	
	private static void usage(String msg)
	{
        System.err.println("Usage: SQLTest -username username -password password -envname envname -seconds seconds");
        System.err.println(msg);
	}
}

The error message: Permission denied: connect reports that when when trying to open the port any firewall/NSG is blocking this outbound port, either, 1433 or redirect port 11000-12000.

If the issue is regarding with port 1433 means that the initial connection with port 1433 is rejecting, if the error message any port from 11000-12000 means that the issue is rejecting any of this port.

As a workaround, if your customer only has the port 1433 as outbound open, please, change the connection policy to Proxy meanwhile their networking team is opening as outbound connection from 11000-12000.

For reference: Azure SQL Database connectivity architecture - Azure SQL Database and Azure Synapse Analytics | Micr...

Enjoy!