C#获取真实IP地址实现方法

通常来说，大家获取用户IP地址常用的方法是：

 string IpAddress = "";
 if((HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]!=null
 && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] !=String.Empty) )
 {
         IpAddress=HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] ;
 }
 else
 {
         HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
 }

事实上，上面的代码只试用与用户只使用了1层代理，如果用户有2层，3层HTTP_X_FORWARDED_FOR 的值是："本机真实IP,1层代理IP,2层代理IP,....." ，如果这个时候你的数据中保存IP字段的长度很小（15个字节），数据库就报错了。

实际应用中，因为使用多层透明代理的情况比较少，所以这种用户并不多。

获取用户真实IP的方法：

 using System;
 using System.Data;
 using System.Configuration;
 using System.Web;
 using System.Web.Security;
 using System.Web.UI;
 using System.Web.UI.WebControls;
 using System.Web.UI.WebControls.WebParts;
 using System.Web.UI.HtmlControls;
 using System.Text.RegularExpressions;
 namespace Common
 {
     /// <summary>
     /// IPAddress 的摘要说明
     /// </summary>
 public class IPAddress : System.Web.UI.Page
 {
     public static Int64 toDenaryIp ( string ip )
     {
         Int64 _Int64 = ;
         string _ip = ip;
         if ( _ip.LastIndexOf ( "." ) > - )
         {
             string[] _iparray = _ip.Split ( '.' );
             _Int64 = Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  *  *  + Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  *  + Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  + Int64.Parse ( _iparray.GetValue (  ).ToString() ) - ;
         }
         return _Int64;
     }
     /// <summary>
     /// /ip十进制
     /// </summary>
     public static Int64 DenaryIp
     {
         get {
             Int64 _Int64 = ;
             string _ip = IP;
             if ( _ip.LastIndexOf ( "." ) > - )
             {
                 string[] _iparray= _ip.Split ( '.' );
                 _Int64 = Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  *  *  + Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  *  + Int64.Parse ( _iparray.GetValue (  ).ToString() ) *  + Int64.Parse ( _iparray.GetValue (  ).ToString() )-;
             }
             return _Int64;
         }
     }
     public static string IP
     {
         get
         {
             string result = String.Empty;
             result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
             if ( result != null && result != String.Empty )
             {
                //可能有代理
                 if ( result.IndexOf ( "." ) == - ) //没有"."肯定是非IPv4格式
                     result = null;
                 else
                 {
                     if ( result.IndexOf ( "," ) != - )
                     {
                          //有","，估计多个代理。取第一个不是内网的IP。
                         result = result.Replace ( " ", "" ).Replace ( "", "" );
                         string[] temparyip = result.Split ( ",;".ToCharArray() );
                         for ( int i = ; i < temparyip.Length; i++ )
                         {
                             if ( IsIPAddress ( temparyip[i] )
                                     && temparyip[i].Substring ( ,  ) != "10."
                                     && temparyip[i].Substring ( ,  ) != "192.168"
                                     && temparyip[i].Substring ( ,  ) != "172.16." )
                             {
                                 return temparyip[i]; //找到不是内网的地址
                             }
                         }
                     }
                     else if ( IsIPAddress ( result ) ) //代理即是IP格式
                         return result;
                     else
                         result = null; //代理中的内容 非IP，取IP
                 }
             }
             string IpAddress = ( HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != String.Empty )  HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] : HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

             if ( null == result || result == String.Empty )
                 result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
             if ( result == null || result == String.Empty )
                 result = HttpContext.Current.Request.UserHostAddress;
             return result;
         }
     }
      //是否ip格式
     public static bool IsIPAddress ( string str1 )
     {
         if ( str1 == null || str1 == string.Empty || str1.Length <  || str1.Length >  ) return false;
         string regformat = @"^\\d{1,3}[\\.]\\d{1,3}[\\.]\\d{1,3}[\\.]\\d{1,3}$";
         Regex regex = new Regex ( regformat, RegexOptions.IgnoreCase );
         return regex.IsMatch ( str1 );
     }
 }
 }