asp.net防类似DDOS攻击(CC攻击)代码

Web.config

<httpModules>
<!–Url重写–>
<add type=”UrlRewriter.RewriterHttpModule, UrlRewriter” name=”UrlRewriter”/>
<!–防类似DDOS攻击–>
<add type=”UrlRewriter.DDosAttackModule, UrlRewriter” name=”DDosAttackModule”/>
</httpModules>

 

 

代码：

using System

;


using System

.Web
;


using System

.Collections

.Generic
;


using System

.Collections

.Specialized
;


using System

.Timers
;


 

namespace UrlRewriter

{


    /// <summary>


    /// 阻止攻击IP地址的回应


    /// </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
;
 //规定时间内访问的最大次数


        private
 const
 int
 REDUCTION_INTERVAL =
 1000
;
 // 1 秒（检查访问次数的时间段）


        private
 const
 int
 RELEASE_INTERVAL =
 5
 *
 60
 *
 1000
;
 // 5 分钟（清除一个禁止IP的时间段）


 

        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>


        /// 检查访问IP


        /// </summary>


        private
 static
 void
 CheckIpAddress(
string ip)


        {


            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


            {


                _IpAdresses[
ip]
 =
 1
;


            }


            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”


            {


                _Banned.Push
(
ip)
;


                _IpAdresses.Remove
(
ip)
;


            }


            else
 //正常访问就加次数 1


            {


                _IpAdresses[
ip]
++;


            }


        }


 

        #region Timers

 

        /// <summary>


        /// 创建计时器，从_IpAddress减去一个请求。


        /// </summary>


        private
 static
 Timer

 CreateTimer(
)


        {


            Timer

 timer =
 GetTimer(
REDUCTION_INTERVAL)
;


            timer.Elapsed
 +=
 new
 ElapsedEventHandler(
TimerElapsed)
;


            return
 timer;


        }


 

        /// <summary>


        /// 创建定时器，消除一个禁止的IP地址


        /// </summary>


        /// <returns></returns>


        private
 static
 Timer

 CreateBanningTimer(
)


        {


            Timer

 timer =
 GetTimer(
RELEASE_INTERVAL)
;


            timer.Elapsed
 +=
 delegate {
 _Banned.Pop
(
)
;
 }
;
 //消除一个禁止IP


            return
 timer;


        }


 

        /// <summary>


        /// 创建一个时间器，并启动它


        /// </summary>


        /// <param name="interval">以毫秒为单位的时间间隔</param>


        private
 static
 Timer

 GetTimer(
int
 interval)


        {


            Timer

 timer =
 new
 Timer

(
)
;


            timer.Interval
 =
 interval;


            timer.Start
(
)
;


 

            return
 timer;


        }


 

        /// <summary>


        /// 减去从集合中的每个IP地址的请求


        /// </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

 

    }


}