07-06-2012 02:48 AM - edited 03-11-2019 04:27 PM
Zone: Outside
Member Interfaces:
Dialer0
Zone: Inside
Member Interfaces:
Virtual-Template1
Vlan1102
Zone: Guest
Member Interfaces:
Vlan1104
Zone-pair : Inside-to-Guest
Source Zone : Inside
Destination Zone : Guest
Service-policy inspect : Zone-Inside-to-Guest
Class-map : Default-Inspection(match-any)
Action : inspect
Class Map type inspect match-any Default-Inspection (id 10)
Description: Default protocol Inspection class
Match protocol tcp
Match protocol udp
Match protocol icmp
My question is: I cannot make it work the ZBF between my internal zones. As you can see above, I've got Zone-Pair: Inside-to-Guest with 'inspect'. Unfortunately, when I tried to ping for the first time, i received:
%FW-6-DROP_PKT: Dropping icmp session GUEST:0 INSIDE:0 due to policy match failure with ip ident 0
It indicated that the traffic going BACK was blocked... WHY? There is 'inspect'
So I created a new pair: Guest-to-Inside and I changed everything to pass. It DID work. But that is not what I wanted! I wanted INSIDE to access GUEST but Guest should not access Inside. I assumed I could do it with 'inspect' but it did now work.
Let me add that I have an exactly the same zone-pair and classes/policies for Inside-to-Outside and it does work with inspect.
Why can I not 'inspect' between my internal zones? Is it because there is no NAT?
07-13-2012 10:47 PM
Hello,
Well there is a problem with the communication the host are trying to make, the router with the ZBFW enable will perform a deep packet inspection in order to investigate and confirm if a session will need to be allowed or not.
In this particular traffic you are seeing here the inspection was not succesfull ( I mean it is being inspected just that the traffic did not pass the test ( Inspection). That is why with a pass/pass on the right zones it works like a charm.
As you know that this traffic is between internal zones the pass/pass it's okay ( It keeps being secure as this is between internal host, and you can restricted by using an ACL.
Regards,
Julio
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07-14-2012 05:09 AM
Do not understand what you are trying to say... zone is a zone (how would a router know it is internal zone? no nat? maybe I am not using nat at all?), why doesn't 'inspect' work between internal zones?
On another board someone suggested it was because I tested it with icmp which is stateless..
07-14-2012 11:10 AM
Hello,
First of all the router can be able to inspect ICMP sessions, he can perform a deep packet inspection and work with the echo and echo-replies.
Now let me explain my self again, I was way too tired yesterday
Traffic between inside to Guest is being inspected but the traffic is not passing the inspection engine ( this could be because of Asymetric routing, invalid payload,etc,etc)
So that being the case that is why the traffic is being allowed with a pass/pass this because the router does not become as specific as with the inspection engine.
Do you see what I mean?
Julio
07-14-2012 11:56 AM
Ok... any reason why it was happening???
What is so special about inside-to-guest (does not work) vs inside-to-outside (works great). Rules, policies etc are the same!
07-14-2012 12:16 PM
Hello,
Again this could be because of invalid flags, invalid tcp headers or payloads,etc.
Now in order o check what is happening you should take captures on both devices ( run wireshark ) and check if you see anything that is not normal on the packets.
Does this happens with all the data exchanged between the servers ( UDP,ICMP,TCP)
What is in between the two subnets besides the router?
Julio
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