pfSense caused asymmetric routing, blocks traffic
I divided my network in multiple subnets. There is traffic between those subnets passing the LAN gateways and related rules. That traffic is largely blocked by the firewall due to “TCP:S”.
I have been investigating the problem and my conclusion is that pf sense handles the traffic between two subnets (LAN-A) and (LAN-B) as follows:
- System-x on LAN-A (192.168.1.x) sends trys to send something to an address in LAN-B (192.168.2.y)
(192.168.1.x to 192.168.1.1 (LAN-A-GW))
- Lan-A-GW knows from the routing table where 192.168.2.y is and send it to that route
(192.168.1.1 to 192.168.2.y)
The response follows the same methodology
- 192.168.2.y to 192.168.2.1
- 192.168.2.1 to 192.168.1.x
As you can see that are two different routes ==> TCP:S ==> Blocked
The route * should * IMHO have been
- 192.168.1.x to 192.168.1.1
- * 192.168.1.1 to 192.168.2.1 *
- 192.168.2.1 to 192.168.2.y
So traffic towards another LAN * should * IMHO always! Go via the corresponding LAN-gateway !
1. Solve the asymmetric routing problem (do not know how to solve that!) AND
2. Would allow the LAN-B gateway to check if the incoming traffic is (in the B-LAN’s opinion) allowed!
In the actual FW setup, your neighbor LAN’s(GW) determine what is allowed to reach your LAN (house) Crazy IMHO !!!
Tested on actual 2.4.4 release 3 version
Note that I did some serious investigation to analyze the problem, and did write some more details in the forum. However the essence is described over here
#1 Updated by Jim Pingle about 1 year ago
- Status changed from New to Not a Bug
- Priority changed from High to Normal