Spark ports to connect to rdbms source using jdbc

[#1]

Hello

I have a spark cluster on CHD 6.3.3
1 master node and 3 worker nodes

I will read huge data from external RDBMS”mssql” using jdbc driver 

And I need to open the port in the firewall

My external RDBMS port is 99766

But my problem is what port should I open from the spark side for each node so I can read and write data using the master and all workers in my spark application.

Thank you 

[#2]

Hi

Apache spark will initiate connection to your db on that port only via jdbc , so you can open a firewall where sources are your nodes ips and destination is your db server ip on the port you specified.

Best Regards