Nethogs → creating socket failed while establishing local IP - are you root?

This is solved by version 0.8.1.

As it's not available in repo nor PPA you need to build it (it is really easy and quickly done).

Fetch and extract the most recent version (as of August 2016, v0.8.5)

wget -c https://github.com/raboof/nethogs/archive/v0.8.5.tar.gz
tar xf v0.8.5.tar.gz 
cd ./nethogs-0.8.5/

Install dependencies and build

sudo apt-get install libncurses5-dev libpcap-dev
make && sudo make install 

Check and run

nethogs -V
sudo nethogs

You can also build from latest source code in the git repository. You still need to install the dependency packages first. After building you can run nethogs from your current directory:

sudo apt-get install libncurses5-dev libpcap-dev
git clone --depth 1 https://github.com/raboof/nethogs.git
cd nethogs
make
sudo ./src/nethogs

You can also find the instructions on the Nethogs project page.