APT repository

# Add the GPG key
curl -s 'https://nobodyinperson.gitlab.io/sshtunnel/gpg.key' | sudo apt-key add -
# Add the repository
echo 'deb https://nobodyinperson.gitlab.io/sshtunnel/ unstable main' | sudo tee -a /etc/apt/sources.list.d/sshtunnel.list
# Update your package cache
sudo apt-get update
# Install packages from the repository
sudo apt-get install sshtunnel