How to record what goes to DROP along the Iptables chain?

Question

linux

A GRE tunnel is connected to the server.
The server receives clean traffic, a chain of rules is set inside the server that receives clean traffic.
N ports are filtered and modeled, when viewing -L -n -v, it displays statistics of received and dropped traffic and the entire chain.
It looks something like this:

How to find out the information that got into DROP? Size/weight/address of the packet that was dropped?
Is it possible, if so, how, to display this information in a separate file in the most detailed form?

Answer 1

Iptables has a LOG action (-j LOG), you may not get all the data you are interested in, but the source/destination address will be available to you.
https://m.habr.com/en/post/259169/