How to create logical subnets with a single Lan interface without VLAN?



  • Hi,

    Is it possible to create logical LAN subnets (172.16.4.0/16, 10.1.9.0/16) without VLAN in pfsense. I was able to do something like this in Sonicwall. Just wanted to know if this is possible with Pfsense.

    All I need is both the subnets should be able to communicate and I should be also be able to give restricted internet access to these subnets.

    I tried these but for some reasons my ping between these two lan subnets works intermittently. But there is no issue with internet. The rules that I have created for these two subnets for internet works well.


    1. Set the Bypass firewall rules for traffic on same interface

    2. Set the lan g/w as 172.16.4.254 and created a virtual IP 10.1.9.254

    3. Created a static route 10.1.0.0/16 to use LANGW 172.16.4.254

    4. Set firewall rule to allow * for these two subnets.


    Regards,
    Raja



  • Rebel Alliance Global Moderator

    This is a broken configuration.. Your trying to run two layer 3 networks over the same physical network.

    If you need two segments, get a 2nd nic for pfsense and use a different dumb switch for the other segment.  Or get a switch that does vlans and run vlans on pfsense phy interface.



  • Hi,

    Thanks for the info. But it looks like  pfsense version 2.1.5 supports this type of network.

    Actually it is working fine for me with a single WAN. I am able to create logical subnets with restricted internet access to these logical subnets. No issues.

    The problem occurs only in dual wan (WAN and OPT). When I configured the WAN failover, the WAN part is working fine without any issues. I am able to view the websites when the line switches to OPT. But for some reasons the LAN subnets gets disconnected when the line switches to OPT.

    When I did a tracert on a LAN IP while on OPT, the first hop always goes to WAN IP instead of pfsense LAN Interface IP.

    Is there  a way to forcibly route through pfsense lan ip?

    Any help would be greatly appreciated.

    Regards,

    Raja


  • Netgate

    Just because you can doesn't mean you should.



  • Hello Derelict,

    I agree that it may not be a standard way. But still when a feature is there why not exploit it?

    Look at the advantage it has… You don't need additional switches and additional nic for subnets.

    Regards,
    Raja


  • Netgate

    And you will end up breaking your network, but go ahead.

    And if you're using it for security, anyone with a sniffer can see what you're doing and just jump on the other "segment" at will.

    And both "segments" are in the same broadcast domain.

    And "routing" between the two requires ICMP redirects.

    And, well, go ahead.

    A managed, gigabit switch is like $60.  I just don't get it.


  • Rebel Alliance Global Moderator

    Well Derelict beat me to some of the problems with doing something like this!!

    My car works if I piss in the radiator vs a antifreeze/water mix as well - does that mean you should run it that way and save on coolant?



  • My car works if I piss in the radiator vs a antifreeze/water mix as well - does that mean you should run it that way and save on coolant?

    What a great idea. Pity I don't have a car, or I would try it.  :D



  • Guys,

    Instead of "Why", if we can switch to "How", there may be a possibility to get a great budget network solution.

    Regards,
    Raja


  • Netgate

    No.  It's ugly, lousy design.

    There is absolutely no reason to run multiple IP subnets in the same broadcast domain, other than, maybe, some temporary renumbering situations.  Emphasis on temporary, as in ephemeral, as in get it finished and turned off as quickly as one can.  (Migrating to a new VLAN is much, much better.)

    Exactly what do you expect to gain?  You get zero security enhancements.  Your firewall can't firewall between them.  All you can, maybe, do is tell your firewall to behave differently for traffic from subnet A and subnet B, but you can do exactly the same thing with a firewall rule than behaves one way for a specific /29 out of a /24 and a different way for the rest (not that it's not trivial to bypass for security - talking more about something like putting all your VOIP phones in the /29 for ease of shaping) - using sound design and without resorting to ugly hacks that really have no place at the table to even be discussed as viable.

    But don't listen to us.  Go for what you know.



  • There is no reason to avoid VLANs when you consider you can have it for about $30 or less.



  • Hi,

    I believe it doesn't end up with one managed switch. I need to change all the end point switches so that it can do vlan.

    I have a client who has network setup as attached. Currently sonicwall is there instead of pfsense and just works without vlan. And thats the reason why I am trying to replicate a similar setup with Pfsense.

    I am ok in having vsphere+ vswitch + pfsense ( all in one box).  Not sure if this works?

    What would be the best way to achieve this?

    Regards,
    Raja



  • Netgate

    That will work just fine with one subnet.  Why do you want multiple layer 3 subnets on a single layer2 segment again?  What do you expect to gain from such a thing?

    And you would not have to change all the edge switches IF all the hosts on each switch are on the same VLAN.  You would tag three VLANS from pfSense to the "core" switch then put each edge switch on an untagged port on each of the three VLANs.  They can be dumb, unmanaged switches.



  • Yep.  Thats the way my network in Maryland works.
    The reason I used multiple VLAN subnets is so I could firewall the LAN segments from "seeing" each other.

    If you are not trying to segregate things, I see no reason to have multiple subnets or VLANs



  • Hi,

    Yes, the subnets has been created for firewalling ( Restricted Lan/Wan Access).

    If you look at the diagram above, there are 3 groups of users connected to different switches.

    Group A - Have access to all internet sites (WAN) + Full access to LAN

    Group B   - Full access to LAN + restricted internet access

    Group C   - Isolated users who can communicate between the same group but cannot communicate with other users/PCS and will have restricted WAN access.

    Actually with the default route, iam able to do all these with pfsense(with deny rule). I have problem only when I configure Gateway groups for loadbalancing/failover. The moment I configure gateway groups, the local subnets gets disconnected.

    Regards,
    Raja


  • Netgate

    Any security you think you're getting from your proposed solution is an illusion.

    Any host can just change its IP address to one of the other subnet schemes and they're now on that "LAN."

    Traffic among the "different LANs" is not dependent on pfSense's firewall to forward.  Any host can also add VIPs on all three subnets and access any host on any subnet at any time and there's not a damn thing your firewall can do about it, because it's not being routed through.



  • Hi,

    The client is ok with that.. Users are not given admin rights to the pcs/registry and hence can't change the IPs.

    Mac ID for each PCs are also in place.

    Believe me or not.. They have been running this setup for past 3 years without any issues.

    Regards,
    Raja


  • Netgate

    OK.  Good luck.



  • ;D



  • Derelict - Are you saying that putting the 3 switches in 3 separate VLANs will not work for isolating them from each other?


  • Netgate

    No.  That absolutely will, providing one doesn't want different VLANs on the same unmanaged edge switch.

    Nothing wrong with the attached config if you can tolerate unmanaged switches in your network.




  • Cool - You scared me for a minute.  Occasionally my thinking gets a correction here…
    Last time I thought I knew something absolutely for sure, I ended up getting punked by CMB.  haha.
    I'm not sure why OP is so opposed to VLANS, but what he said about the client computers being locked down gave me this idea:

    Assuming he is correct and the network is PHYSICALLY secure.  No one can plug/unplug things and the machines are truly secured and no config changes can be made, he could just control what can and can not be accessed on each client machine's firewall.  Seems to me the only other way to do it.  Other than running 3 separate LAN NICs or VLANs.

    I wouldn't recommend that though.


  • Netgate

    VLANs are far easier than maintaining the necessary MAC address lists.  And since MACs can be easily spoofed, far more effective.

    US$500 gets managed switches all around (cheap ones, but light years better than the proposed hack).

    Dude doesn't want to listen and that's fine with me.  I'm not the one on call when it blows up.



  • Even at $500 he would be doing himself a favor.

    But seriously, for $30 to $50 he could get a VERY nice used managed gigabit switch with a ton of ports from someone on ebay who is upgrading to 10GB…

    You think I make a habit of buying all new hardware?  I'd be broke...  I have stuff everywhere.

    (I buy hardware for people with the condition to run my services on their bandwidth)



  • Hi,

    Mac can be spoofed.. Even vlans are not secure. A determined person can still put a plug on vlan port can still gain access to the vlan. But Iam not going into this now. And its hard for me to convince my client to buy additional hardwares. He has been living with this network for years.

    If my configuration will work, why is that I have problems when configuring gateway groups( load balancing) in pfsense. Is this a known issue with pfsense? Whennever I configure gateway groups, the first hop always goes to the wan router instead of my pfsense router. I believe it should be a simple routing issue. Not sure how to fix this. I am just new to pfsense.

    Regards,
    Raja


  • Rebel Alliance Global Moderator

    You don't run multiple layer 3 over the same layer 2 - you do not do this, this is wrong.. I don't care what the client says.  Why do they even think it is possible??  Let them setup their own network then - I wouldn't have anything to do with this.  If they are so freaking cheap they wont spend pennies to get the correct hardware - they sure and the hell can not be paying you anything worth doing something this wrong!!


  • Netgate

    @cceraja:

    Is this a known issue with pfsense? Whennever I configure gateway groups, the first hop always goes to the wan router instead of my pfsense router. I believe it should be a simple routing issue. Not sure how to fix this. I am just new to pfsense.

    No.  It's a known issue with hokey, broken network design.  All sorts of wacky crap will happen.  Expect it.


  • Netgate

    @cceraja:

    Even vlans are not secure. A determined person can still put a plug on vlan port can still gain access to the vlan.

    Umm, yes.  Plug into an enabled port on the VLAN and you're on the VLAN.  That's sort of the point.  Controlling such access is a completely separate problem, which might be solved using 802.1x if that's what you're worried about.  You'd need managed switches though.  ;)

    If you're talking about VLAN hopping I'll need to see an example with modern gear to believe it's still a viable hack.


  • Rebel Alliance Global Moderator

    @Derelict:

    No.  It's a known issue with hokey, broken network design.  All sorts of wacky crap will happen.  Expect it.

    Oh that made my morning!!  Always good to start the day with a laugh!! ;) heheeheheh



  • @cceraja:

    Hello Derelict,

    I agree that it may not be a standard way. But still when a feature is there why not exploit it?

    Look at the advantage it has… You don't need additional switches and additional nic for subnets.

    Regards,
    Raja

    That's not a feature, it's an undefined configuration that is highly recommended against. Kind of like people using a high or low IP address of a subnet. It can work in some setups, but expect strange stuff to happen.