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：

 1 string IpAddress = "";
 2 if((HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]!=null 
 3 && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] !=String.Empty) )
 4 {
 5         IpAddress=HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] ;
 6 }
 7 else
 8 { 
 9         HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]; 
10 }

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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：

 1 using System;
 2 using System.Data;
 3 using System.Configuration;
 4 using System.Web;
 5 using System.Web.Security;
 6 using System.Web.UI;
 7 using System.Web.UI.WebControls;
 8 using System.Web.UI.WebControls.WebParts;
 9 using System.Web.UI.HtmlControls;
10 using System.Text.RegularExpressions;
11 namespace Common
12 {
13     /// <summary>
14     /// IPAddress 的摘要说明
15     /// </summary>
16 public class IPAddress : System.Web.UI.Page
17 {
18     public static Int64 toDenaryIp ( string ip )
19     {
20         Int64 _Int64 = 0;
21         string _ip = ip;
22         if ( _ip.LastIndexOf ( "." ) > -1 )
23         {
24             string[] _iparray = _ip.Split ( '.' );
25             _Int64 = Int64.Parse ( _iparray.GetValue ( 0 ).ToString() ) * 256 * 256 * 256 + Int64.Parse ( _iparray.GetValue ( 1 ).ToString() ) * 256 * 256 + Int64.Parse ( _iparray.GetValue ( 2 ).ToString() ) * 256 + Int64.Parse ( _iparray.GetValue ( 3 ).ToString() ) - 1;
26         }
27         return _Int64;
28     }
29     /// <summary>
30     /// /ip十进制
31     /// </summary>
32     public static Int64 DenaryIp
33     {
34         get {
35             Int64 _Int64 = 0;
36             string _ip = IP;
37             if ( _ip.LastIndexOf ( "." ) > -1 )
38             {
39                 string[] _iparray= _ip.Split ( '.' );
40                 _Int64 = Int64.Parse ( _iparray.GetValue ( 0 ).ToString() ) * 256 * 256 * 256 + Int64.Parse ( _iparray.GetValue ( 1 ).ToString() ) * 256 * 256 + Int64.Parse ( _iparray.GetValue ( 2 ).ToString() ) * 256 + Int64.Parse ( _iparray.GetValue ( 3 ).ToString() )-1;
41             }
42             return _Int64;
43         }
44     }
45     public static string IP
46     {
47         get
48         {
49             string result = String.Empty;
50             result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
51             if ( result != null && result != String.Empty )
52             {
53                //可能有代理
54                 if ( result.IndexOf ( "." ) == -1 ) //没有"."肯定是非IPv4格式
55                     result = null;
56                 else
57                 {
58                     if ( result.IndexOf ( "," ) != -1 )
59                     {
60                          //有","，估计多个代理。取第一个不是内网的IP。
61                         result = result.Replace ( " ", "" ).Replace ( "", "" );
62                         string[] temparyip = result.Split ( ",;".ToCharArray() );
63                         for ( int i = 0; i < temparyip.Length; i++ )
64                         {
65                             if ( IsIPAddress ( temparyip[i] )
66                                     && temparyip[i].Substring ( 0, 3 ) != "10."
67                                     && temparyip[i].Substring ( 0, 7 ) != "192.168"
68                                     && temparyip[i].Substring ( 0, 7 ) != "172.16." )
69                             {
70                                 return temparyip[i]; //找到不是内网的地址
71                             }
72                         }
73                     }
74                     else if ( IsIPAddress ( result ) ) //代理即是IP格式
75                         return result;
76                     else
77                         result = null; //代理中的内容 非IP，取IP
78                 }
79             }
80             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"];
81            
82             if ( null == result || result == String.Empty )
83                 result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
84             if ( result == null || result == String.Empty )
85                 result = HttpContext.Current.Request.UserHostAddress;
86             return result;
87         }
88     }
89      //是否ip格式
90     public static bool IsIPAddress ( string str1 )
91     {
92         if ( str1 == null || str1 == string.Empty || str1.Length < 7 || str1.Length > 15 ) return false;
93         string regformat = @"^\d{1,3}[\.]\d{1,3}[\.]\d{1,3}[\.]\d{1,3}$";
94         Regex regex = new Regex ( regformat, RegexOptions.IgnoreCase );
95         return regex.IsMatch ( str1 );
96     }
97 }
98 }

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