c# 用户登陆限制，错误登陆次数不超过3次15分钟内

思路：

 1,通用配置（错误次数与间隔时间）可以修改，不需要发布代码

2，用户登录错误次数>=设定的错误次数，进行判断在时间内不能累加错误次数，弹出提示

3，间隔时间外错误次数清0

4，用户名不存在，记录IP判断次数(走一次用户名存在密码错误的过程，不要直接加黑ip ，可能有情况的)

5, 用户登录密码错误时 错误次数累加 与 时间记录

6，登录成功，错误次数清0

上代码

 public UserEntity CheckLogin(string username, string password)
        {
            UserEntity userEntity = service.CheckLogin(username);
            var errorCount = Config.GetValue("ErrorCount").ToInt();
            var errorTime = Config.GetValue("ErrorTime").ToInt();
            if (userEntity != null && userEntity.OrganizeId != "")
            {
                if (userEntity.EnabledMark == 1)
                {
                    if (userEntity.ErrorCount != null && userEntity.ErrorCount >= errorCount)
                    {
                        DateTime errortime = Convert.ToDateTime(userEntity.ErrorTime);
                        //Subtract函数减去指定时间，返回一个时间差，时间的格式可以是分钟也可以是秒、小时
                        TimeSpan span = DateTime.Now.Subtract(errortime);
                        double minute = span.TotalMinutes;//取时间间隔的分钟数

                        if (minute < errorTime)
                        {
                            throw new Exception("您已经连续" + errorCount + "次输入密码错误，请" + errorTime + "分钟之后再次重试!");


                        }
                        else
                        {
                            userEntity.ErrorCount = 0;
                            service.SaveForm(userEntity.UserId, userEntity);

                        }
                    }

                    string dbPassword = Md5Helper.MD5(DESEncrypt.Encrypt(password.ToLower(), userEntity.Secretkey).ToLower(), 32).ToLower();
                    if (dbPassword == userEntity.Password)
                    {
                        //登录成功后，错误次数清0
                        userEntity.ErrorCount = 0;

                        DateTime LastVisit = DateTime.Now;
                        int LogOnCount = (userEntity.LogOnCount).ToInt() + 1;
                        if (userEntity.LastVisit != null)
                        {
                            userEntity.PreviousVisit = userEntity.LastVisit.ToDate();
                        }
                        userEntity.LastVisit = LastVisit;
                        userEntity.LogOnCount = LogOnCount;
                        userEntity.UserOnLine = 1;

                        service.UpdateEntity(userEntity);
                        return userEntity;
                    }
                    else
                    {
                        userEntity.ErrorCount = (userEntity.ErrorCount==null?0:userEntity.ErrorCount).ToInt() + 1;
                        userEntity.ErrorTime = System.DateTime.Now;
                        service.UpdateEntity(userEntity);
                        throw new Exception("密码和账户名不匹配!");
                    }
                }
                else
                {
                    throw new Exception("账户名被系统锁定,请联系管理员!");
                }
            }
            else
            {
                //判断客户端IP限制
                FilterIPEntity filterIPEntity = filterService.CheckErrorIp(Net.Ip);
                if(filterIPEntity!=null)
                {
                    
                    if (filterIPEntity.ErrorCount!=null&&filterIPEntity.ErrorCount >= errorCount)
                    {
                        DateTime errortime =Convert.ToDateTime(filterIPEntity.ErrorTime);
                        //Subtract函数减去指定时间，返回一个时间差，时间的格式可以是分钟也可以是秒、小时
                        TimeSpan span = DateTime.Now.Subtract(errortime);
                        double minute = span.TotalMinutes;//取时间间隔的分钟数
                                                            
                        if (minute < errorTime)
                        {
                            throw new Exception("您已经连续"+errorCount+"次输入账号密码错误，请"+errorTime+"分钟之后再次重试！");
                            
                            
                        }
                        else
                        {
                            filterIPEntity.ErrorCount = 0; 
                            filterService.SaveForm(filterIPEntity.FilterIPId, filterIPEntity);
                            
                        }

                    }
                    else
                    {
                        filterIPEntity.ErrorCount = (filterIPEntity.ErrorCount == null ? 0 : filterIPEntity.ErrorCount).ToInt() + 1;
                        filterIPEntity.ErrorTime = System.DateTime.Now;
                        filterService.SaveForm(filterIPEntity.FilterIPId, filterIPEntity);
                    }
                      
                }
                else
                {
                    filterIPEntity = new FilterIPEntity();
                    filterIPEntity.ErrorCount = (filterIPEntity.ErrorCount==null?0:filterIPEntity.ErrorCount).ToInt() + 1;
                    filterIPEntity.ErrorTime = System.DateTime.Now;
                    filterIPEntity.ErrorIp = Net.Ip;
                    filterService.SaveForm("", filterIPEntity);
                   
                }
                 throw new Exception("账户名或密码错误，请重新输入！");
            }
        }

代码有些冗余的，自行处理

   获取IP代码

        /// <summary>
        /// 获取Ip
        /// </summary>
        public static string Ip
        {
            get
            {
                var result = string.Empty;
                if (HttpContext.Current != null)
                    result = GetWebClientIp();
                if (result.IsEmpty())
                    result = GetLanIp();
                return result;
            }
        }

        /// <summary>
        /// 获取Web客户端的Ip
        /// </summary>
        private static string GetWebClientIp()
        {
            var ip = GetWebRemoteIp();
            foreach (var hostAddress in Dns.GetHostAddresses(ip))
            {
                if (hostAddress.AddressFamily == AddressFamily.InterNetwork)
                    return hostAddress.ToString();
            }
            return string.Empty;
        }

        /// <summary>
        /// 获取Web远程Ip
        /// </summary>
        private static string GetWebRemoteIp()
        {
            return HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] ?? HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
        }

        /// <summary>
        /// 获取局域网IP
        /// </summary>
        private static string GetLanIp()
        {
            foreach (var hostAddress in Dns.GetHostAddresses(Dns.GetHostName()))
            {
                if (hostAddress.AddressFamily == AddressFamily.InterNetwork)
                    return hostAddress.ToString();
            }
            return string.Empty;
        }