I was trying to set up two wildfly instances running in two different machines. I need them to know that they are in the same cluster.
If I start up two wildfly instances in the same machine with port-offset, there will be no firewall blocking port numbers that are used for communication between two instances, and I can see that each instance recognizes the they are in the same cluster (using -Djboss.node.name parameter).
After I set up a virtualbox with two VM (different IP), and I deployed the wildfly instance to the two VMs, the two VMs now work independently without knowing they are in the same group. If I disable the firewall in both VM, they will know they are in the same cluster. But that is not what should be. So I need to configure firewall to allow certain port number to be open up.
However, I found jgroups related port number also use multicast. How to configure firewall to allow multicast communication between these two VM?