How can I make sure that port 8787 works

[pierrot10]

Good day,

I ma managing a cluster with centos 7.
All work fine. The firewall is disable and we can display a web page (port 80) about the cluster status.
On the master I installed Rstudio server and the procedure asked me to enable the firewall and open the port 8787. Later I had to open the port 80 as well.
The problem is since I enabled the firewall, the nodes do not communicate with the master.

From this point, I have a couple of question:
I would like to disable the firewall as before. But how can make sure that Rstudion server work with the port 8787?
And why the nodes can communicate with the Master, while the port 8787 can not, when the firewall is disabled?

If I absolutely need to enable the firewall, is there a command to let me know which port I have to open for the node?

I would prefer to leave my cluster as it is (the firewall disabled) but port 8787 would not work...

Many thank for your advises.
Cheers
Pierre

[tunk]

I have no experience with Rstudio and I'm not sure if I understand your setup.
I think I would start with looking at the documentation. As for opening ports in
the firewall, it depends on if you're using firewalld (default) or iptables.
You can use nmap to see if ports are open, e.g.:
nmap -p 8787,80 dns.name.or.ip.address

[TrevorH]

No firewall means ALL ports are open including 8787.