I am on Linux platform with MySQL NDB 5.7. I am trying to monitor all traffic related to MySQL clustering – between data nodes, management node and sql nodes. To that end, I used netstat to list all open ports listening on my machine before starting MySQL cluster. Then, I started MySQL cluster and ran netstat again. I assumed that the ports that were listening the second time around, but not the first time, were related to MySQL clustering.
But there are two problems with this. First, there could be ports opened by other processes between the two netstat runs. Second, MySQL might open other ports after I ran the netstat command the second time.
What is the best way to go about finding all ports being used by MySQL for clustering purposes?
I believe ephemeral ports are picked dynamically, so perhaps if I knew all the MySQL clustering related processes that would be running, I can figure out every port that they are using. Pointers will be very welcome.
If you have access to the server, you can just look at the MySQL server configuration to see how the cluster is configured. There you can see how many nodes are in the cluster pool and determine their ports per spec.
Hi,
I'm not sure to fully understand your question, but it wonder if you are not mixing several concepts.
Indeed, unless a an application runs with root privileges, it cannot open or close a port itself. Ports can be opened or closed at the OS level, for instance using its firewall UI. In other words, MySQL (or any other app) doesn't need to run for its related ports being open or close. In fact, MySQL will not be able to run properly if the port(s) it uses are not open before it is launched. Thus, checking if ports are open or close will probably not be a solution for you. If I'm right (but again, I'm not sure to have fully understood your question), you need to check the traffic on the (open) ports. A right tool to do this is tcpdump. You'll find several examples around, for instance at http://superuser.com/questions/604998/monitor-tcp-traffic-on-specific-port
Hope this helps.
Thanks very much @ Jourquin! It is very interesting and worth reading info.
Greetings,
As @Ala said with nmap you can see opened ports but if ports are being used will be blocked to MySQL. It is safer the option that propose @Jourquin. But you can combine techniques. But with nmap you can select other ports not listed and add you rules for them in the iptables. Also this way there is the risk if you install another tool with tcp traffic, can generate conflict. To sum, check your port environment, add to iptables new one and reconfigure MySQL. I think is a right way to do it.
Bests.