We need create a CentOS 6.8 server with public IP address on the host, an Ubuntu Server 16.04. First enable CPU virtualization tech in BIOS. Then run:
sudo apt install virtualbox
sudo apt install vagrant
vagrant box add bento/centos-6.8
mkdir -p $HOME/vms/ddaas; cd $HOME/vms/ddaas
vagrant init bento/centos-6.8
# add this line in Vagrantfile: config.vm.network "public_network", ip: "172.18.0.251"
vagrant up
Now you can login to this new vm server with ssh vagrant@172.18.0.251
(password vagrant) using a SSH client in LAN.