https://github.com/fail2ban/fail2ban/blob/master/config/action.d/nftables.conf

<nftables> add table inet <table>
<nftables> -- add chain inet <table> <chain> \{ type <chain_type> hook <chain_hook> priority <chain_priority> \; \}
              %(_nft_add_set)s

<chain_type> filter
chain_hook = input
chain_priority = -1

<nftables> add element inet <table> addr-set-<name> \{ <ip> \}

addr-set-<name> - The name of the nft set used to store banned addresses
