[Linux Firewall Configuration]

nftables.conf

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
	chain ports {
		tcp dport 33333 counter accept
	}

	chain input {
		type filter hook input priority filter; policy drop;
		ct state established,related counter accept
		ct state invalid counter drop
		iif != lo ip6 daddr ::1/128 counter drop comment "drop connections to loopback not coming from loopback"
		# ip protocol icmp accept
		icmpv6 type { echo-request,nd-neighbor-solicit,nd-neighbor-advert,nd-router-solicit,nd-router-advert,mld-listener-query,destination-unreachable,packet-too-big,time-exceeded,parameter-problem } accept
		iifname lo counter accept
		ip protocol tcp jump ips
		ip protocol tcp jump ports
	}

	chain ips {
	}


	chain forward {
		type filter hook forward priority 0; policy drop;
		counter drop comment "Drop forwarded packets since this isn't a router"
	}

	chain output {
		type filter hook output priority 0; policy accept;
	}
}