//首先我们要实现 IHttpModule接口using System;using System.Collections.Generic;using System.Text;using System.Web;using System.Web.UI;using System.Web.SessionState;using System.Configuration;namespace MyHttp{    public class UrlReWrite : IHttpModule    {        /// 
        /// 单个IP最大连接限制数量        /// 
        private int rowCount = Convert.ToInt32(ConfigurationSettings.AppSettings["HttpRowCount"]);        /// 
        /// 指定区域时间范围 单位分        /// 
        private int httpTime = Convert.ToInt32(ConfigurationSettings.AppSettings["HttpTime"]);        public void Init(HttpApplication application)        {            application.BeginRequest += (new                 EventHandler(this.Application_BeginRequest));            application.EndRequest += (new                 EventHandler(this.Application_EndRequest));        }        private void Application_BeginRequest(Object source, EventArgs e)        {            HttpApplication Application = (HttpApplication)source;            HttpContext ctx = Application.Context;            //IP地址            string isIp = ctx.Request.UserHostAddress;            if (ctx.Application["time"] == null)            {                ctx.Application["time"] = DateTime.Now;            }            else            {                DateTime isTime = (DateTime)ctx.Application["time"];                int timeTract = Convert.ToInt32(DateTime.Now.Subtract(isTime).Minutes.ToString());                if (timeTract > (httpTime - 1))                {                    ctx.Application["time"] = null;                    ctx.Application["myip"] = null;                }            }            if (ctx.Application["myip"] != null && ctx.Application["myip"] is CartIp)            {                CartIp cartIp = (CartIp)ctx.Application["myip"];                cartIp.Insert(isIp);                ctx.Application["myip"] = cartIp;                if (cartIp.GetCount(isIp) > rowCount)                {                    ctx.Response.Clear();                    ctx.Response.Close();                }            }            else            {                CartIp cartIp = new CartIp();                cartIp.Insert(isIp);                HttpContext.Current.Application["myip"] = cartIp;            }        }        private void Application_EndRequest(Object source, EventArgs e)        {        }          public void Dispose()        {        }    }} //ListIp 类 using System;using System.Collections.Generic;using System.Text;namespace MyHttp{    [Serializable]    public class ListIp    {        private string ip;        private int count;        /// 
        /// IP地址        /// 
        public string IP        {            get { return ip; }            set { ip = value; }        }        /// 
        /// 累加数量        /// 
        public int Count        {            get { return count; }            set { count = value; }        }    }    [Serializable]    public class CartIp    {        public CartIp()        {            if (_listIp == null)            {                _listIp = new List
     
      ();            }        }        private List
      
        _listIp;        public List
       
         _ListIp        {            get { return _listIp; }            set { _listIp = value; }        }        /// 
        
        /// 添加IP        /// 
        public void Insert(string ip)        {            int indexof = ItemLastInfo(ip);            if (indexof == -1)            {                //不存在                ListIp item = new ListIp();                item.IP = ip;                _listIp.Add(item);            }            else            {                _listIp[indexof].Count += 1;            }        }        //判断IP是否存在        public int ItemLastInfo(string ip)        {            int index = 0;            foreach (ListIp item in _ListIp)            {                if (item.IP == ip)                {                    return index;//存在                }                index += 1;            }            return -1;//不存在        }        /// 
        
        /// 获得IP的数量        /// 
        /// 
                /// 
                public int GetCount(string ip)        {            foreach (ListIp item in _ListIp)            {                if (item.IP == ip)                {                    return item.Count;//存在                }            }            return -1;//不存在        }    }}  //在web.config 配置访问规则
        
         
         
         
           
            
            
         
        
       
      
     

来源：http://www.cnblogs.com/Fooo/archive/2013/01/27/2878820.html