https://github.com/adrienverge/openfortivpn
Homebrew
# install via homebrew
brew install openvpn-connect --cask
Edit the config
cd /usr/local/etc/openfortivpn/openfortivpn/
vi config
host = vpn-host
port = vpn-port
username = username
password = pwd
# trusted-cert = certificatedigest4daa8c5fe6c...
# trusted-cert = othercertificatedigest6631bf...
Simple and good to use.