The way to find out is from the terminl
Code:
sudo iftop -nNP
for a port listening application.  
<t> toggles through incoming/outgoing/both.
<shift><p> pauses the bouncing refresh.
Find the offending 
IP:port and tack it on to the end of 
Code:
sudo netstat -tnp | grep 192.168.0.4:34931
like the 
192.168.0.4:34931 is done.
That will return the name of the process using that IP and port.
There is a 'simpler' method but that requires additional software (nethogs, 
sudo apt-get install nethogs)