asp.net 防ddos(cc)攻击代码

asp.net防类似DDOS攻击(CC攻击)代码001	Web.config 
002	   
003	<httpModules> 
004	 <!–Url重写–> 
005	 <add type=”UrlRewriter.RewriterHttpModule, UrlRewriter” name=”UrlRewriter”/> 
006	 <!–防类似DDOS攻击–> 
007	 <add type=”UrlRewriter.DDosAttackModule, UrlRewriter” name=”DDosAttackModule”/> 
008	 </httpModules> 
009	  
010	using System; 
011	using System.Web; 
012	using System.Collections.Generic; 
013	using System.Collections.Specialized; 
014	using System.Timers; 
015	   
016	namespace UrlRewriter 
017	{ 
018	    /// <summary> 
019	    /// 阻止攻击IP地址的回应 
020	    /// </summary> 
021	    public class DosAttackModule : IHttpModule 
022	    { 
023	        void IHttpModule.Dispose() { } 
024	   
025	        void IHttpModule.Init(HttpApplication context) 
026	        { 
027	            context.BeginRequest += new EventHandler(context_BeginRequest); 
028	        } 
029	   
030	        private static Dictionary<string, short> _IpAdresses = new Dictionary<string, short>(); 
031	        private static Stack<string> _Banned = new Stack<string>(); 
032	        private static Timer _Timer = CreateTimer(); 
033	        private static Timer _BannedTimer = CreateBanningTimer(); 
034	   
035	        private const int BANNED_REQUESTS = 1; //规定时间内访问的最大次数 
036	        private const int REDUCTION_INTERVAL = 1000; // 1 秒（检查访问次数的时间段） 
037	        private const int RELEASE_INTERVAL = 5 * 60 * 1000; // 5 分钟（清除一个禁止IP的时间段） 
038	   
039	        private void context_BeginRequest(object sender, EventArgs e) 
040	        { 
041	            string ip = HttpContext.Current.Request.UserHostAddress; 
042	            if (_Banned.Contains(ip)) 
043	            { 
044	                HttpContext.Current.Response.StatusCode = 403; 
045	                HttpContext.Current.Response.End(); 
046	            } 
047	   
048	            CheckIpAddress(ip); 
049	        } 
050	   
051	        /// <summary> 
052	        /// 检查访问IP 
053	        /// </summary> 
054	        private static void CheckIpAddress(string ip) 
055	        { 
056	            if (!_IpAdresses.ContainsKey(ip)) //如果没有当前访问IP的记录就将访问次数设为1 
057	            { 
058	                _IpAdresses[ip] = 1; 
059	            } 
060	            else if (_IpAdresses[ip] == BANNED_REQUESTS) //如果当前IP访问次数等于规定时间段的最大访问次数就拉于“黑名单” 
061	            { 
062	                _Banned.Push(ip); 
063	                _IpAdresses.Remove(ip); 
064	            } 
065	            else //正常访问就加次数 1 
066	            { 
067	                _IpAdresses[ip]++; 
068	            } 
069	        } 
070	   
071	        #region Timers 
072	   
073	        /// <summary> 
074	        /// 创建计时器，从_IpAddress减去一个请求。 
075	        /// </summary> 
076	        private static Timer CreateTimer() 
077	        { 
078	            Timer timer = GetTimer(REDUCTION_INTERVAL); 
079	            timer.Elapsed += new ElapsedEventHandler(TimerElapsed); 
080	            return timer; 
081	        } 
082	   
083	        /// <summary> 
084	        /// 创建定时器，消除一个禁止的IP地址 
085	        /// </summary> 
086	        /// <returns></returns> 
087	        private static Timer CreateBanningTimer() 
088	        { 
089	            Timer timer = GetTimer(RELEASE_INTERVAL); 
090	            timer.Elapsed += delegate { _Banned.Pop(); }; //消除一个禁止IP 
091	            return timer; 
092	        } 
093	   
094	        /// <summary> 
095	        /// 创建一个时间器，并启动它 
096	        /// </summary> 
097	        /// <param name="interval">以毫秒为单位的时间间隔</param> 
098	        private static Timer GetTimer(int interval) 
099	        { 
100	            Timer timer = new Timer(); 
101	            timer.Interval = interval; 
102	            timer.Start(); 
103	   
104	            return timer; 
105	        } 
106	   
107	        /// <summary> 
108	        /// 减去从集合中的每个IP地址的请求 
109	        /// </summary> 
110	        private static void TimerElapsed(object sender, ElapsedEventArgs e) 
111	        { 
112	            foreach (string key in _IpAdresses.Keys) 
113	            { 
114	                _IpAdresses[key]--; 
115	                if (_IpAdresses[key] == 0) 
116	                    _IpAdresses.Remove(key); 
117	            } 
118	        } 
119	   
120	        #endregion 
121	   
122	    } 
123	}