Usage
curl -sSL https://gist.githubusercontent.com/ttimasdf/ef739670ac5d627981c5695adf4c8f98/raw/autossh@host1 | \
sudo tee /etc/default/autossh@example
curl -sSL https://gist.githubusercontent.com/ttimasdf/ef739670ac5d627981c5695adf4c8f98/raw/autossh@.service | \
sudo tee /etc/systemd/system/autossh@.service
sudo useradd -g nogroup -s /bin/false -m tunnel
sudo -u tunnel mkdir -p ~tunnel/.ssh # and copy your private key here