Nowadays, crawlers are very popular. If we want to curb this behavior, firewalls can help us a lot, such as limiting the number of visits per minute and so on.
In addition to using -m limit, there is one more REJECT, because after the rule is matched, the next chain must be matched. If it does not match, it will default to ACCEPT, so it is necessary to add a second chain:
You can see that after receiving five messages, it was banned