asp.net防類似DDOS攻擊(CC攻擊)代碼

< DOCTYPE html PUBLIC -WCDTD XHTML StrictEN httpwwwworgTRxhtmlDTDxhtml-strictdtd>

Web.config
 
<httpModules>
 <!-Url重寫->
 <add type=”UrlRewriter.RewriterHttpModule, UrlRewriter” name=”UrlRewriter”/>
 <!-防類似DDOS攻擊->
 <add type=”UrlRewriter.DDosAttackModule, UrlRewriter” name=”DDosAttackModule”/>
 </httpModules>
 
 
 
代碼：
 
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using System;
using System.Web;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Timers;
 
namespace UrlRewriter
{
    /// <summary>
    /// 阻止攻擊IP地址的回應
    /// </summary>
    public class DosAttackModule : IHttpModule
    {
        void IHttpModule.Dispose() { }
 
        void IHttpModule.Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }
 
        private static Dictionary<string, short> _IpAdresses = new Dictionary<string, short>();
        private static Stack<string> _Banned = new Stack<string>();
        private static Timer _Timer = CreateTimer();
        private static Timer _BannedTimer = CreateBanningTimer();
 
        private const int BANNED_REQUESTS = 1; //規定時間內訪問的最大次數
        private const int REDUCTION_INTERVAL = 1000; // 1 秒（檢查訪問次數的時間段）
        private const int RELEASE_INTERVAL = 5 * 60 * 1000; // 5 分鐘（清除一個禁止IP的時間段）
 
        private void context_BeginRequest(object sender, EventArgs e)
        {
            string ip = HttpContext.Current.Request.UserHostAddress;
            if (_Banned.Contains(ip))
            {
                HttpContext.Current.Response.StatusCode = 403;
                HttpContext.Current.Response.End();
            }
 
            CheckIpAddress(ip);
        }
 
        /// <summary>
        /// 檢查訪問IP
        /// </summary>
        private static void CheckIpAddress(string ip)
        {
            if (!_IpAdresses.ContainsKey(ip)) //如果沒有當前訪問IP的記錄就將訪問次數設為1
            {
                _IpAdresses[ip] = 1;
            }
            else if (_IpAdresses[ip] == BANNED_REQUESTS) //如果當前IP訪問次數等於規定時間段的最大訪問次數就拉於“黑名單”
            {
                _Banned.Push(ip);
                _IpAdresses.Remove(ip);
            }
            else //正常訪問就加次數 1
            {
                _IpAdresses[ip]++;
            }
        }
 
        #region Timers
 
        /// <summary>
        /// 建立計時器，從_IpAddress減去一個請求。
        /// </summary>
        private static Timer CreateTimer()
        {
            Timer timer = GetTimer(REDUCTION_INTERVAL);
            timer.Elapsed += new ElapsedEventHandler(TimerElapsed);
            return timer;
        }
 
        /// <summary>
        /// 建立定時器，消除一個禁止的IP地址
        /// </summary>
        /// <returns></returns>
        private static Timer CreateBanningTimer()
        {
            Timer timer = GetTimer(RELEASE_INTERVAL);
            timer.Elapsed += delegate { _Banned.Pop(); }; //消除一個禁止IP
            return timer;
        }
 
        /// <summary>
        /// 建立一個時間器，並啟動它
        /// </summary>
        /// <param name="interval">以毫秒為單位的時間間隔</param>
        private static Timer GetTimer(int interval)
        {
            Timer timer = new Timer();
            timer.Interval = interval;
            timer.Start();
 
            return timer;
        }
 
        /// <summary>
        /// 減去從集合中的每個IP地址的請求
        /// </summary>
        private static void TimerElapsed(object sender, ElapsedEventArgs e)
        {
            foreach (string key in _IpAdresses.Keys)
            {
                _IpAdresses[key]--;
                if (_IpAdresses[key] == 0)
                    _IpAdresses.Remove(key);
            }
        }
 
        #endregion
 
    }
}

轉載保留 : http://blog.wuaiwei.com/2011/04/02/asp-net%e9%98%b2%e7%b1%bb%e4%bc%bcddos%e6%94%bb%e5%87%bb%e4%bb%a3%e7%a0%81/

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