There's a great thread on [ask ubuntu](https://askubuntu.com/questions/104739/which-applications-are-using-internet) on seeing which applications are using the Internet. I'm going to add my own spin on the answers for future reference.
```bash
lsof -i | awk '{print $1}' | uniq | tail -n +2
```
Breaking it down...
-`lsof -i` shows us a lot of information pertaining to processes accessing the Internet.
-`awk '{print $1}'` filters the last output to only shown us the `COMMAND` column.
-`uniq` filters out multiple occurrences of a single application.
