NAT between LAN and WAN + filtering bridge between WAN and OPT

  • Hi,
    My ISP will not let me use my own router behind their modem. THey provided me with a cheap "home gateway" that authenticates with the modem through 802.1x protocol over wired connection (so on lower level than IP protocol,i have sniffed the packets between gateway and modem that iwould like to let through). If this gateway does not authenticate then the modem will not renew any dhcp lease. So basically here is the setup I want to achieve :

      my computers - - - - - -|LAN             |
                               |       PF box    |
                               |              WAN|--------------- modem
      home gateway- - - - - -| OPT            |

    Basically have a "normal" WAN-LAN NAT connection (WAN gets it's ip through dhcp).
    But in addition in order for modem to renew dhcp lease i need to let some packets (on ethernet level) through between home gateway –- opt -- wan --- modem (and other way round too).
    I've attached the kind of packets I want to let through opt to wan an back.

    Is this possible?
    Any hint on what i need to setup on pfsense box ? A bridge between opt and wan since the packets i want to let trough are on lower level than tcp/ip ?


    PS If anyone in Japan knows how to use your own router on KDDI hikari one service without jumping through those hoops please let me know