How to route a /30 subnet

  • Hi all.

    I apologize if this seems basic but while I know how to do this easily on Cisco devices I just want to confirm how to do this properly in pfSense. The status is that I have a static IP provided from my ISP using PPPoE with pfSense as my main router. I want to assign another public and static IP to a device in my network but not sure how to do that using PPPoE.

    My ISP says that in addition to my current static IP they would assign me a /30 subnet that would be routed to my current static public IP then I would be responsible for routing that to my internal devices. Is it as simple as creating a static route from the PPPoE interface to another interface? Wouldn't that mean that I would have to have one IP address for the interface then another for the device?

    Any insight on how I can set this up would be appreciated.



  • LAYER 8 Netgate

    Generally, yes. You would assign the /30 to an inside interface which would chew up 3 of the 4 addresses in the /30 leaving one for the device. You would make sure outbound NAT rules do not match the traffic so no NAT is performed out WAN.

    pfSense understands /31 netmasks so you could do two /31 interfaces and be able to use two of the addresses. The hosts involved would need to be good with /31 addressing too.

    You could, perhaps, make one /31 interface and route the other /31 to the host on that interface. That way you might be able to use 3 publics on that server (think http virtual hosts, etc). I've never tried it.

Log in to reply