Hey keep in mind Isilon is a NAS device. I just want to make sure your posting in the right place.
If this is the right place trying "sockstat -l" or "netstat -l"
Granted this will probably only show you the open ports on the node you are on so you will have to be careful running this command as a cluster wide command output cause the output will be huge if all the nodes have an external port connected to a production network.
I hope this helps!