First configuration : NAT
-
@freyja I can't get it working either after playing with it for a few minutes. I wonder if this is another manifestation of the multi-wan NAT bug?
-
For this to work - the IPs that would be natted would have to exist on pfsense interface - so @KOM you setup vips in this 10.1.10 network on pfsense?
If you have a network 10.1.10 as lan, and 10.1.12 as dmz
And you want to hit 10.1.10.X and get natted 1:1 to dmz that .X would have to be an IP on pfsense lan interface. Or why would the traffic ever get sent to pfsense to get natted and sent to its 1:1 match up in 10.1.12
Here - I setup a vip on my lan 192.168.9.32, setup a 1:1 nat to 192.168.3.32 (my dmz vlan)
Now I ping 192.168.9.32 from client on my lan 192.168.9.100, it gets answers. And via the sniff done on pfsense dmz interface you can see the traffic was sent and answered by 192.168.3.32
Now if this has something to do with the multi wan nat issue - but seems to be working as expected on 21.02.2
This sort of setup just doesn't make any sense from any way you look at.. Be it you hide the actual IP from lan or not - the access is still there..
-
@johnpoz Sure did. When I couldn't get it going, I double-checked the docs at
https://docs.netgate.com/pfsense/en/latest/nat/1-1.html
In my KVM lab, I created my VIP on my DMZ, then a 1:1 NAT to a Mint box on LAN. Server on DMZ could not ping the VIP successfully. Now I also have block rules on DMZ to prevent traffic to LAN, but I assumed the NAT would bypass that. Perhaps I'm wrong?
-
Do you have rule that prevents access to your vip?
-
@johnpoz The DMZ, VIP and ubuntu server are all on the same subnet so rules shouldn't matter, but no I don't have anything specific to that VIP.
Block to VLAN20 net
Block to LAN net
Allow DMZ to Anyand that's it.
-
So you still need a rule that allows the nat.. Here I just blocked access on lan to 192.168.3.32
And if try and ping 192.168.9.32 it fails.
-
@johnpoz I added an Allow rule on DMZ for my VIP and it still doesn't work.
Do me a favour and recreate your test going the other way, DMZ to LAN instead of LAN to DMZ? My tiny brain is spinning trying to keep my lab setup, your config and his config all straight.
Meanwhile it's lunchtime. Back in a few.
-
Ok flipped it - doesn't matter
Put the vip on the dmz interface, setup the 1:1 nat on the dmz interface, created a firewall rule to allow that access to the 9.100 IP..
Works just fine..
For my next trick - I will go wash my car in the rain.. Then water my lawn.. Same sort of nonsense as doing this sort of thing.
-
@johnpoz OK I got it working. I had my allow rule pointing to my VIP instead of the LAN address I was natting to.
-
Yeah the nat rule is evaluated before the firewall rule - but the actual traffic has to be allowed for it to work.. Just like any normal port forward..
-
@johnpoz I know all of that which makes it extra-stupid on my part.
-
Hi both, thanks for your investigations.
However, it's not a single IP I would like to nat 1:1 but a whole network.
If you need screens, I'll post them this afternoon.
-
And how would you do that when some IPs on the network you want to nat are on device on that L2..
If you have 10.1.10 on A, and 10.1.12 on B you can not 1:1 nat either of those for a whole network.. You would need a 3rd network. Say 10.1.11
-
@johnpoz why that ?
Of course I would not NAT the server IP.
Honestly, it's working with the Pix and it's bugging me it's not working with pfSense/Netgate :(Should I make a NAT exception for the Server IP and the pfSense IP (if possible)?
-
You can't have the same IP in 2 places. if you have device 10.1.10.x on a device in A, how can you also say 10.1.10.x nats to 10.1.12.x
In my example, I don't have a 192.168.9.32 device, nor do I have a 192.168.3.100 device
-
@johnpoz I don't have such device, the only concern is how pfsense is handling arp, does it create a nat only when a device goes through the netgate or does it make a reservation for the whole network ?
Basically if internall I don't have a 10.10.12.1 device, i will not have any problem reaching the server in DMZ, of course if I have a 10.10.10.1 device and try to reach 10.10.12.1 from it, it wont work but that's not what I have.
So should I configure a /24 1:1 NAT (with eventually a NAT exclusion if necessary and possible) or should I break it down in smaller subnets (/25, etc)? Better option: can we nat an IP range instead of a subnet?
-
If you create vip in a range.. It will answer arp for any of those IPs.. The only way to create such a range is via the proxy arp vip.
This can be problematic if you have a host in that actual range. On which device answers the arp first, or at all..
Like I said your complicating the design of the network - for no real added security at all. More complex leads to greater chance of issues, greater chance of configuration mistakes..
There is really no reason to nat rfc1918 to rfc1918.. I could see doing it if you were trying to get a device without a gateway to talk to something else in another vlan.. If you needed vlans that are on the same IP space to be able to talk to each other.. There are some reasons where you might have to do it.
I am not seeing it at all in this scenario.. It sure is not a security anything to do it this way, if anything it reduces your overall security because your more complex setup makes for more likely mistakes that expose more than you desire.
-
@johnpoz there are plenty of reasons I'm doing this but that's not the subject (again, the simple fact I want to reproduce what I already have should be enough for you).
I guess I will have to find by myself or ask somewhere else.
At least with cisco I had plenty of different scenarii cases I can try (with plenty of errors I have to admit).
I've never been in front of such hostility on what I'm trying to implement.
-
@freyja No hostility. Asking why you're doing what you're doing isn't an attack. Maybe you're doing something unusual to get around some edge case we haven't seen before and we could learn from it. Either way you seem quite reluctant to explain what you're doing.
there are plenty of reasons I'm doing this
Like what, for instance?
In a lot of cases, people decide on a course of action that is either wrong or sub-optimal and they ask specific questions when they would be better off explaining what they want to accomplish and getting suggestions on the best way to do it with pfSense.
Anyway, you have been given your NAT solution. There is no automatic way to map every LAN client to a VIP on your DMZ and a NAT for that VIP. You will have to set them up one by one.
-
Hi,
I was able to make the NAT work, it was a typo in the subnet mask of the interface (/32 instead of /24).
My inside devices are correctly natted into DMZ according to their LAN IP (i.e. 10.10.10.20 natted to 10.10.12.20).However, it looks like I have an ARP problem, the netgate doesn't answer arp request for these IP except its own IP.
If I force the entry in ARP table of my server the flow is working perfectly.
Any idea ?
