NoDDoS

NoDDoS v6. 2. 9 Technical Overview

NoDDoS is a lightweight security utility for Minecraft 1. 21+ designed to mitigate packet-based exploits and automated bot joins. The system uses an Atomic Sliding Window algorithm to monitor incoming traffic per-player, ensuring that rate limits cannot be bypassed by timing packets at the end of a second. It operates with high concurrency safety using ConcurrentHashMap and Atomic variables to maintain server stability during high-load events.

Core Functionality:

Packet Filtering: Specifically monitors CUSTOM_PAYLOAD, CHAT, and WINDOW_CLICK packet types. Join Rate Limiting: Implements a two-tier threshold (Normal and Burst) to distinguish between server restarts and bot attacks. Progressive Punishment: Increases ban duration based on the frequency of violations from a specific IP address. Resource Efficiency: Uses asynchronous cleanup tasks and single-kick scheduling to minimize main-thread impact.

Configuration (config.yml):

``` settings: # Maximum allowed player joins per second under normal conditions joins-per-second: 5 # Burst join limit - Reaching this triggers the progressive ban system burst-limit: 15 # Maximum simultaneous connections allowed from a single IP address max-connections-per-ip: 2 # Maximum packets (Chat, Click, Payload) allowed per second per player max-packets-per-second: 300

messages: prefix: "&8[&6NoDDoS&8] " # Message when the normal join limit is reached global-cooldown: "&cThe server is currently busy! Please wait a few seconds and try again." # Message when an IP exceeds the connection limit ip-limit: "&cToo many connections from this IP. Please logout from your other accounts." # Kick message for packet flooding packet-spam: "&cSuspicious packet traffic detected! Connection closed for security." # Message for players currently blocked by the progressive ban system blacklisted: "&cYour IP has been temporarily blocked due to suspicious activity. Please wait." # Message sent to admins after reloading the plugin reload: "&aConfiguration reloaded and violation records cleared!" ```

Technical Requirements:

Java 21 and Java 25 ProtocolLib dependency required for packet interception.