Most servers with port 25565 open get hits from either Minecraft griefer bots, or from a bot that looks for that port and warns anyone on that server about the

Most servers with port 25565 open get hits from either Minecraft griefer bots, or from a bot that looks for that port and warns anyone on that server about the risks of leaving that port open. It doesn't take a huge scale operation to spam every IPv4 address in the world, there are only 2^32 of them, and even then many of those addresses are reserved.