WAN /26 into 2x DMZ /27 and multiple LANs using vlan.



  • Trying to setup a 3/4 legged firewall, WAN, LAN, N1, N2 on a XG-1537

    We have a x.x.x.128 /26 network from the ISP that we want to split into two sub networks:

    N1: x.x.x.128/27 (129-158) 30 addresses, gw: x.x.x.129, bc: x.x.x.159
    N2: x.x.x.160/27 (161-190) 30 addressers, gw: x.x.x.161, bc: x.x.x.191

    N1 should be routed but without firewall
    N2 should be routed and behind firewall

    LAN will use NAT and segmented into multiple vlans each with own subnets all behind firewall.

    On the XG-1537
    N1 is on interface ix1
    N2 is on interface ix0
    WAN is on interface igb1 (SFP+)
    LAN is on interface igb0 (SFP+)

    Does pfsense need to have an ip address on both N1 and WAN?
    Should N1 and WAN be bridged?
    WAN should have an address from N1, but what subnet mask /26 or /27 ?
    What is needed from the ISP? Certain config or otherwise?

    x.x.x.129 is ISP Gateway.

    Any help or experience with similar setups is much appreciated, thanks.


  • LAYER 8 Netgate

    They need to give you a small interface network, like a /29 or /30, and route the /26 to you on that.



  • …usually referred to as transit network.
    Otherwise you cannot route.



  • @Derelict:

    They need to give you a small interface network, like a /29 or /30, and route the /26 to you on that.

    Thanks for the quick reply!

    Is there a way to do it without any ISP changes? Proxy arp?

    I am thinking that the fw has an external IP on the WAN interface ex. x.x.x.141/26 or x.x.x.141/27 from N1 address range.

    Then on the N2 interface it has an IP from the N2 address range e.g. x.x.x.161/27 and Proxy ARP enabled?

    The N1 (.128/27) range has x.x.x.129 as gateway same as the complete block (0.128/26) - so any server setup directly on the WAN with an ip between .130-158 /27 side should work without any ISP setup right?
    The only reason for having a N1 interface for the N1 range is that the external network comes in directly to the SFP+ port on the firewall - I do not have a switch with SPF+ before the firewall - so I was thinking to bridge the N1 interface to the WAN interface.

    Does this make sense?


  • LAYER 8 Netgate

    Why are people so hesitant to ask their ISP for a properly-configured network being content instead with hacks and fudged workarounds?



  • @Derelict:

    Why are people so hesitant to ask their ISP for a properly-configured network being content instead with hacks and fudged workarounds?

    That I do not know. But I would like to know how to setup pfsense for my use case. Thanks.


  • LAYER 8 Netgate

    It is a complete hack to do what you are trying to do with a /26 on WAN.

    I told you what you need to do. Get your ISP to configure your circuit with a properly-routed subnet.



  • @Derelict:

    They need to give you a small interface network, like a /29 or /30, and route the /26 to you on that.

    So I can get my ISP to make a /29 'transit network / link net'. So I guess I declare to the ISP which ip within my /26 that acts as the gateway/router for the /26? And then that gateway/router is assigned the ISP gateway of the /29 correct?

    This gateway/router is in this case the pfsense firewall. But in practical terms how do I split/use my /26 so I get a firewalled DMZ with public ips and a non-firewalled DMZ with public ips using pfsense?

    I have 4 interface on the pfsense firewall. Ideally I would use 1 for WAN, 1 for LAN, 1 for firewalled DMZ and 1 for non-firewalled DMZ. (Potentially also using vlans to isolate public ips from each other on the DMZs).

    Best regards


  • LAYER 8 Netgate

    Actually you (or your ISP) declare which IP address on the /29 the /26 is routed to.

    Once you have the /26 routed to you you can do whatever you want with the addresses.

    Just split it into two /27s and use those as the interface addresses for the DMZ networks and disable NAT for them.

    Example (in Cisco-ish Speak):

    Their Side:

    Interface (transit) network:

    interface ethernet 0/0
      ip address 198.51.100.1 255.255.255.248

    Routed /26 Subnet:

    ip route 192.0.2.0 255.255.255.192 198.51.100.2

    Your side:

    Interface (transit) network:

    interface WAN
      ip address 198.51.100.2 255.255.255.248

    DMZ Networks

    /27

    interface DMZ
      ip address 192.0.2.1 255.255.255.224

    /27

    interface DMZ1
      ip address 192.0.2.33 255.255.255.224

    ip route 0.0.0.0 0.0.0.0 198.51.100.1



  • @Derelict Thanks for your recommendation. I can only agree that it is much more clean and easy to configure with a link/transit network.

    (Due to some ISP issues with a new fiber it took forever to proceed with the case.)

    Followed the guide here: https://docs.netgate.com/pfsense/en/latest/book/routing/routing-public-ip-addresses.html
    all great expect for the outbound NAT instructions. I had to change to "Manual Outbound NAT rule generation (AON - Advanced Outbound NAT)" and delete the auto generated rules. It was not enough to use the hybrid with NO NAT options.

    Link net/transit net /29 (WAN)
    Inside net /28 split into two /27 (DMZ1 and DMZ2)
    RFC1918 /16 (LAN)

    BR


  • LAYER 8 Netgate

    @desrux2 said in WAN /26 into 2x DMZ /27 and multiple LANs using vlan.:

    It was not enough to use the hybrid with NO NAT options.

    That is enough. You should have posted what you had when it wasn't working because there was probably a mistake made.



  • @Derelict said in WAN /26 into 2x DMZ /27 and multiple LANs using vlan.:

    @desrux2 said in WAN /26 into 2x DMZ /27 and multiple LANs using vlan.:

    It was not enough to use the hybrid with NO NAT options.

    That is enough. You should have posted what you had when it wasn't working because there was probably a mistake made.

    Sure thing.

    Not working:
    4D127110-328D-4A5A-B79B-FA27EF4D3D4B.jpeg
    B4009A9C-5DAD-416E-956B-A07B28D02878.jpeg

    Working (I would assume I can also remove the NO NAT):
    5DE1F0DC-75CE-4820-9A0E-BB8841EC5EDB.jpeg
    E84B35C4-01F6-4FEC-961F-6FE741B49E9A.jpeg



  • @Derelict
    Found the issue. The NO NAT settings had somehow lost the interface assignment. It would look correct in the settings but not until clicking save (without changing anything) would the WAN show up in the menu.

    4DB697D7-9079-4E0E-A2A5-67A8AFC2F296.jpeg

    I wonder if this happens if the firewall has experienced at some point loosing said interface during boot?


  • LAYER 8 Netgate

    I don't know. I have never seen that. booting after losing an assigned interface should trigger interface reassignment.


  • LAYER 8 Moderator

    I'd not go with "no NAT" rules but instead switch to manually configuring NAT, delete the automatic copied entries that aren't needed (those on the IFs with public IPs) and be done :)



  • @JeGr Agreed!


  • LAYER 8 Netgate

    In an HA environment where all NAT needs a custom rule I would agree.

    I like the NO NAT rules in this case. The routed subnet is unlikely to change, leaving Automatic NAT in place.

    Personal preference, of course.


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