Behind another firewall

  • I had my existing firewall on my network, and i want pfsense behind it as my ips/ids, how can i setup my pfsense behind existing firewall.
    this what i want to do.

    ISP => Existing Firewall => pfsense => switch => workstations.

  • Well, you have a couple of options, you can setup a double NAT, or you can setup a bridge. Then you would setup snort to monitor the interfaces.

  • Please send me a step by step instruction how to setup in bridge mode,, am i newbie. tnx

  • or in NAT i dont know how to setup in NAT mode please help..

  • NAT is the default mode. You should be able to use it as is if you have the WAN and LAN setup.

  • sorry sir but in not NAT mode the setup that i would like to be in my pf sense box. I want it in bridge mode. bcause i will use my existing firewall as my gateway.

  • Then you will need to set NAT to manual and remove all NAT rules created. Then follow the tutorial for bridge (which includes the NAT disabling).,50711.0/topicseen.html
    Have fun.

  • I've already red that tutorial but nothing happens still can't ping LAN side of my existing firewall from workstation passing through PFsense box.
    I want to know the physical connections of LAN cables. I already plug on all Ports that i have in the pfsense box but still i cant get ip from dhcp server of my existing firewall..


  • You have to create the special rules in the bride to pass that type of traffic. What I would do for now is to allow all protocols on any source or destination on any port to pass. Once you have it working, then you can change it to be more restrictive. I would also hard set an IP to test if only dhcp configured systems are affected.

  • how will i do that? please…. tnx

  • If you followed the guide, you are going to have a LAN wan and opt interface. Opt I think would need to be wide open. LAN would also need to allow most thinks in. Then you are going to create in bound rules on the wan interface. It has been a long time since I did a firewalled bridg e perhaps I need to refresh.

  • Sir Thank You very much for your support it was a success..

    On the other hand i had another question to ask you,,, on that setup the topic that we've talked, is it possible to trunk LAN and WAN, how?

  • sir how can i setup this bridge mode in vlan. i have my layer 2 switch with vlan..

  • For trunking, I guess you could do LAGG interfaces into the bridge, though I have never done that before.
    It would imagine that it would be the same for VLAN. Assign VLANs to WAN and LAN (or opt1 and opt2 with the bridge on opt3) and then create the bridge out of them. Again, I am theorizing as I have don't have experience doing that either.

  • Hi Sir
    this is the setup that i have and we discussed earlier.

    ISP => Existing Firewall => PFSense => Switch => workstations

    This setup has been solved
    The new setup is like this:

    ISP => Existing Firewall => PFSense => Layer 3 switch setup with VLAN's => workstations connected to VLAN's

    My VLAN's can ping each other without PFSense.
    But when i setup PFSense in transparent bridge mode. I can't obtain ip from existing firewall. how can i setup my network like this with PFSense in Bridge Mode.


  • You will have to create an interface per each VLAN you have setup. The apply all those interfaces into the bridge. Though, if you have VLANs, is your existing firewall handing out DHCP address on each VLAN in a different subnet?

  • Hi sir, yes sir, I have created 9 VLAN's in my existing firewall with DHCP on it. How can i set up this with PFsense on bridge mode?

  • And in different subnets the 9 VLAN's

  • Sorry, I think you are going to have to create 18 VLANs (1 on WAN and its matching one on LAN). Then put each matching VLAN into its own bridge. I think that is going to be the only way that the VLAN tag will survive.

  • I can't understand you sir,, how can i create 18 VLAN's if i have 3 NIC's on my PFSense box? RL0 as my WAN, DC0 as my LAN and DC1 as the OPT1 as where i assign my RL0 and DC0 bridge.

    on other i had my 9 VLAN's setup on my existing firewall (Zyxell USG 1000)


  • and sir I always see this pop up message on my pfsense box: DC0 TX underrun – increasing TX threshold .. what is the meaning of this?

  • @semperfi:

    and sir I always see this pop up message on my pfsense box: DC0 TX underrun – increasing TX threshold .. what is the meaning of this?

    Not sure about this … perhaps a driver or NIC issue. Perhaps there is a tweak in the advanced options you can do to prevent that ... search the forums and google.

    The 9 VLANs you have on the Zyxell has to go somewhere. I assumed they are on the same NIC as the LAN port. If you are putting the pfsense box inline, the VLAN tag must survive the traversal of the pfsense machine. If you are assigning each VLAN its own nic, then perhaps you really don't need VLANs. You can have many VLAN on one physical NIC. Please see docs server for info on how to setup VLANS in pfsense.
    So in pfsense, you are going to create a VLAN on WAN and a matching one on LAN (opt2 and opt3) then you are going to assign them to opt4 as a bridge. So for each VLAN on the Zyxell, you will have 2 on the pfsense machine. This is to pass the VLAN traffic on. If you are hooking it up in parallel with the VLANs and you are only wanting to block traffic on the default VLAN, then don't worry about the setup, you already have it working.

  • I create alieases for the VLAN's

  • rule for bridge

  • Rule for LAN

  • rule for OPT1

  • rule for WAN

  • Sir I dont know it is correct but my Network is working fine i can access Zyxell and PFSense, i Have my internet..

    Please check,,

    How can i use bandwith limiter for every network and transparent proxy + dansguardian

    Thanks sir,,

  • All of your VLAN are able to pass through the bridge and are able to get to the internet?

    I am not familiar with the limiter or dansguardian, I use the squid3 package for proxying. It is easy to setup and you would only need to tell it what subnets you want to proxy on and it will do that.

  • Yes sir all of the VLAN's able to ping each other and has internet.
    I want to ask you if this setup is ok?  this were I come up, because its different from your setup..
    I can't understand your concept, on how to set up my network,

    we successfully setup pfsense in transparent bridge mode behind my Zyxell firewall,,
    the problem is with this set as my WAN=rl0 and LAN=dc0 was bridge in opt1. I cant imagine how can i assign this 3 NIC's because its already in use…

  • If it is working, you don't need to do anything. I didn't think that VLAN ids would be kept intact when passing over the bridge much less be able to see any subnets in it. If you remove a VLAN subnet from your alias, does that VLAN no longer work? how is your network connected?

  • when i removed one VLAN subnet on my aliase. and i use that VLAN port on my Layaer 2 switch, icant ping my pfsense, my zywall even i cant get ip from dhcp server..

  • This would mean that filtering is working as expected. Just install the packages you want and configure them to allow all your subnets. Once everything is working, you can start restricting if you want.

  • In this st up I want to limit download and upload in my network,, example i want to limit download and upload in VLAN 2 with the network of, how can i dothis

  • You can do this with limiter, traffic shaper, or squid … The best way depends on what you want to limit as in, all traffic, traffic on certain ports, or just web based download and upload. I am most familiar with the shaper and you can do this with that using a penalty setup. Just run the wizard and when you see penalty ip, put in the entire VLAN2 subnet. You can then create other penalty queues for other subnets. If you want to just have a physical cap, you would use the limiter, but I am not sure how to set that up as I have never used it. (Something for me to learn soon)

  • sir how can i use transparent proxy in transparent bridge mode


  • I have not done this before, but I would speculate that you just need to install squid3, set is to listen on WAN and LAN, and check the option to be transparent.

  • ok sir thank I'll try the squid3..

  • how to use this squid3 sir?

  • Where are you having trouble? Perhaps some questions. Search, there is probably a doc or a forum write up for a simple starter config.

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