# (I) Firewall config /etc/sysctl.conf
    sysctl -w net.inet.ip.forwarding=1 net.inet.ip.fw.enable=1
    sysctl -a net.inet.ip.forwarding net.inet.ip.fw.enable

    ipfw list
    ... shoud have ....
    net.inet.ip.forwarding=1
    net.inet.ip.fw.enable=1


    # (II) Enable nat access to /etc/pf.conf
    #============add your host-only vlan =================
    # this commented lines doesn't work after computer reboot
    #nat on en0 from vboxnet0:network -> (en0)
    #nat on en3 from vboxnet0:network -> (en3)
    # this will work in any situation
    nat on en0 from 10.1.100.0/24 to any -> (en0)
    nat on en3 from 10.1.100.0/24 to any -> (en3)
    #==========================

    # Reload pf
    pfctl -f /etc/pf.conf
    pfctl -e