Blocklists for iptables / ipset

ipset create blocklist hash:net -exist
curl -fsSL "https://www.team-cymru.org/Services/Bogons/fullbogons-ipv6.txt" | grep -Eo '^[0-9]{1,3}(.[0-9]{1,3}){3}(/[0-9]{1,2})?' | 
  while read -r net; do ipset add blocklist "$net" -exist; done
iptables -I INPUT  -m set --match-set blocklist src -j DROP
iptables -I FORWARD -m set --match-set blocklist src -j DROP

Persist the set and re-run the download from cron to keep it current:

ipset save blocklist -f /etc/ipset.blocklist
# /etc/cron.daily/blocklist