Port 6311

Port 6311 is the port on which the native component in R (Rserve) is listening to accept connections from Java (see http://rforge.net/Rserve/faq.html for more details). This port need not to be exposed to remote machines, just by way of localhost/loopback.

To check if the port is open, run the following command from the command line on the computer running the R Connector.

$netstat -anp | grep 6311
 
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
 
tcp  0  0 127.0.0.1:6311    0.0.0.0:*     LISTEN  8627/Rserve

If netstat is not available, you can try running nmap, telnet, or another port checker to test if this port is available at least on localhost.