If you want the information in a Terminal you can run
sudo lsof -i which will tell you all open internet connections (and listening processes too).
Your screenshot shows no anomaly, nothing unexpected (except maybe tomcat). So take one more step to investigate: you are going to look at actual bandwidth used in any connection with external hosts.
For this you need to
- install iftop by typing
sudo apt-get install iftop
- run it with
sudo iftop (or maybe
sudo iftop -i wlan0 if the first command gives an error)
You will get a picture like
where the top line shows the overall used bandwidth (here very little bandwidth is used at the moment).