Solving Asymmetric Routing: Accessing LAN Devices with Misconfigured Gateways

 

Issue:

Managed switch at 192.168.1.2 was reachable via ARP but "filtered" on all ports during Nmap scans over OpenVPN. The switch had a misconfigured Default Gateway (.254 instead of .1.1), causing a routing dead-end where the switch could receive packets but couldn't route replies back to the 10.8.0.0/24 VPN subnet.

Temporary Resolution (VPN):

Implemented a Hybrid Outbound NAT rule in pfSense on the LAN interface. This masqueraded VPN traffic as coming from the LAN interface IP (192.168.1.1), tricking the switch into responding to a local address. Once GUI access was gained, the System Default Gateway was corrected to 192.168.1.1 and saved to flash.

Resolution:

Update switch gateway to correct gateway. In this case it was .254 to .1

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