How to build/install sniffer on open-wrt?

Question

linux

wi-fi router tp-linkwr741nd (my personal)
If possible, do not touch the iron or touch it to a minimum.
Send sniffed data via the Internet or store in the memory of the router / flash drive (which will have to be soldered [if possible without it)
The goal is to completely sniff all the data that passes through the router.
I googled and didn't find anything useful. Well, I'm not good at it.

Answer 1

Easy to install
How do you imagine it?
Your router does not have the ability to use a flash drive, and the router's memory is so small that tcpdump will fill it up in a few minutes.

Answer 2

Yes, any internal memory will fill up quickly. Is it possible to mount CIFS in the local area and drop it there ...