Replying to
@jwz@mastodon.social
@jwz@mastodon.social @randomwizard@social.vivaldi.net
Last time I looked, ec2 instances still have editable iptables so he was answering your question. If you can't use a load balancer then you must implement the block on the instance itself. Iptables are the way to achieve that.
https://repost.aws/knowledge-center/ec2-linux-configure-iptables-nftables