I'm trying to pass a very specific UDP packet from one interface to another on different networks on the same router. I've run a packet capture on both interfaces, I can see the packet coming in on the input interface but it just disappears after that. There are no firewall logs indicating the packet was blocked. I've tried sending the packet through with the firewall and NAT disabled but it still doesn't get processed. I'm convinced its either the interface or Kernel blocking the packet before the firewall can process it.
If anyone has any tips on where I can look to see why the packet is being blocked that would be great. Any help would be appreciated here as I'm at a complete loss on where to troubleshoot next.