Dear VPP community,
I hope this message finds you well.
I am currently working on a VPP-based traffic monitoring program and would like 
to ask for your advice regarding the integration of a custom node and the 
snort_plugin.
What I want to achieve:

 * 
My own custom program intercepts packets at the device-input feature arc.

 * 
At the same time, I need to duplicate the incoming packets (from dpdk-input) 
and send a copy to snort_plugin for intrusion detection, while my custom node 
still processes the original packets.

 * 
Therefore, I modified the snort_plugin node to attach to device-input instead 
of the default ip4-unicast.
What I observed:

 * 
From show trace, packets do go through snort-enq.

 * 
show runtime also shows non-zero counters for both snort-enq and snort-deq.

 * 
However, Snort (the external process) does not generate any alert, even though 
the same Snort configuration works when snort_plugin is attached to ip4-unicast.
My questions:

 * 
Is the above design (moving snort_plugin to device-input) considered 
reasonable? Could there be any missing prerequisites (e.g., L2 header not yet 
processed, or missing flow information) that prevent Snort from properly 
inspecting the packets?

 * 
If this design is not optimal, what alternative solutions would you recommend 
to achieve both (a) custom processing at an early stage and (b) sending a 
duplicate copy of the original packets to Snort?
Any suggestions or pointers to relevant documentation/examples would be greatly 
appreciated.
Thank you very much for your time and help.
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