I've installed OpenSnitch, a GNU/ Linux port of the rather well known macOS application Little Snitch…
Here's how-to build and install against an already properly configured go1.10.4 linux/amd64—slightly adopted from github.com/evilsocket/opensnitch/README.md:
# system dependencies
sudo apt-get install git libnetfilter-queue-dev libpcap-dev protobuf-compiler python3-pip
# src
go get github.com/golang/protobuf/protoc-gen-go
cd $GOPATH/src/github.com/golang/dep
git checkout master
go get -u github.com/golang/dep/cmd/dep
./install.sh
export PATH=$PATH:$GOPATH/bin
python3 -m pip install --user grpcio-tools
go get github.com/evilsocket/opensnitch
cd $GOPATH/src/github.com/evilsocket/opensnitch
# build and install daemon and ui
make
sudo make install
sudo systemctl enable opensnitchd
sudo service opensnitchd start
# had to manual build and autostart ui
cd ui
sudo /home/matthias/.local/bin/pip3 install -r requirements.txt
sudo /home/matthias/.local/bin/pip3 install .
cp opensnitch_ui.desktop ~/.config/autostart/Some pointers:
tail -f /var/log/opensnitchd.log