# File lib/vagrant-lxc/action/prepare_nfs_settings.rb, line 44
        def add_ips_to_env!(env)
          provider = @machine.provider

          host_ip    = read_host_ip
          machine_ip = provider.ssh_info[:host]

          raise Vagrant::Errors::NFSNoHostonlyNetwork if !host_ip || !machine_ip

          env[:nfs_host_ip]    = host_ip
          env[:nfs_machine_ip] = machine_ip
        end