Allow Non-NAT Traffic to Pass Through DET44 Plugin

[den1s]

Description

I am using the det44_plugin.so plugin in VPP with the following configuration:

• DET44 Interfaces:

  • Input interface: eth0.100
  • Output interface: eth0.200

• Mappings:

  • Input network: 192.168.99.0/24
  • Output network: 1.1.1.0/24

Currently, when traffic is received on the local interface (eth0.100), if the source IP (src_ip) does not fall within the NAT pool (i.e., 192.168.99.0/24), the traffic is dropped. However, I propose modifying this behavior to allow such traffic to pass through to the output interface (eth0.200) according to the FIB (Forwarding Information Base) without applying NAT.

Use Case

This change is necessary to support scenarios where the local interface (eth0.100) receives both:

1. Traffic from BOGON networks (private or non-routable addresses) that requires NAT.
2. Traffic with public IP addresses that should not be NATed but simply forwarded according to the FIB.

By allowing non-NAT traffic to pass through, the DET44 plugin can handle mixed traffic more flexibly, improving its usability in environments where both NAT and non-NAT traffic coexist on the same interface.

Proposed Solution

Modify the DET44 plugin to:

1. Check if the src_ip of incoming traffic on the local interface falls within the configured NAT pool.
2. If it does, apply NAT as usual.
3. If it does not, forward the traffic to the output interface according to the FIB without dropping it.