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Routing Question, how to avoid "could not associate packet to any connection"

Ok this is tricky to describe:

Sophos XG firewall at 192.168.1.251 - Has static route to 192.168.3.X network via 192.168.1.253 router

Server A at 192.168.1.17 - Has default route of 192.168.1.251, Has no static routes defined

Sophos UTM firewall at 192.168.1.252 - Has static route to 192.168.3.X networks via 192.168.1.253

Cisco Router at 192.168.1.253 and 192.168.3.253 - Has 192.168.3.X network as a vlan with, Has 192.168.1.252 as default router, has routing enabled to route between subnets

Workstation A at 192.168.3.65 and default gateway of 192.168.3.253

Situation is that Server A can initiate contact with Workstation A, but Workstation A cannot initiate contact with Server A

When I review the XG log it shows that traffic from 192.168.1.17 to 192.168.3.65 is being blocked as invalid traffic with message of "could not Associate Packet to any connection".  From what I can tell this is that because Server A is sending the traffic back through the XG firewall and the XG firewall is not seeing the workstations initial Packet as it's coming directly from the Router at 192.168.1.253. 

I know I can "fix" this by adding a Static route to the Server A "Route add 192.168.3.0 MASK 255.255.255.0 192.168.1.253" but that is kind of messy and I would rather handle with the routers. 

You might wonder why I have this config and it's because we are transitioning from the UTM firewall to the XG and some servers are connecting to the Internet via the XG firewall and some still via the UTM firewall. 

Any way to make this work other than adding the static routes to the servers?  Maybe some way to tell the XG to quit acting like a stateful router for the traffic between those subnets?



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  • Hi  Thanks for sharing the information with us here, based on the provided information it seems there is an "asymmetric routing design" because of that this situation is getting observed here. Ideally one should avoid "asymmetric routing design" but if you require it due to some specific reasons then in such cases on XG CLI you may add "advanced firewall bypass stateful inspection firewall rule" in the CLI console.

    Sophos Firewall/Sophos UTM: Identify an asymmetric routing design condition
    https://support.sophos.com/support/s/article/KB-000038267?language=en_US

    For command reference, you may refer below KBA where you can replace source and destination IP as per your setup and need. This rule can be added for the host aswell  though below KBA has an example with network-based command. 

    Sophos Firewall: Bypass stateful inspection
    support.sophos.com/.../KB-000044309

    Regards,

    Vishal Ranpariya
    Technical Account Manager | Sophos Technical Support

    Sophos Support Videos | Knowledge Base  |  @SophosSupport | Sign up for SMS Alerts |
    If a post solves your question use the 'Verify Answer' link.

  • This sounds like my situation (asymmetric routing) and what I am looking for as far as a "solution".  Will these rules that bypass the stateful inspection show up in the GUI?  If they are only visible in the CLI then I would be worried they would never get "cleaned up" after I did not need them anymore.   Regardless I will give it a try. 

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  • This sounds like my situation (asymmetric routing) and what I am looking for as far as a "solution".  Will these rules that bypass the stateful inspection show up in the GUI?  If they are only visible in the CLI then I would be worried they would never get "cleaned up" after I did not need them anymore.   Regardless I will give it a try. 

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