大家获取用户IP地址常用的方法是
C# 代码
复制
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
C# 代码 复制
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 = 0; string _ip = ip; if ( _ip.LastIndexOf ( "." ) > -1 ) { string[] _iparray = _ip.Split ( '.' ); _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; } return _Int64; } /// <summary> /// /ip十进制 /// </summary> public static Int64 DenaryIp { get { Int64 _Int64 = 0; string _ip = IP; if ( _ip.LastIndexOf ( "." ) > -1 ) { string[] _iparray= _ip.Split ( '.' ); _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; } 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 ( "." ) == -1 ) //没有"."肯定是非IPv4格式 result = null; else { if ( result.IndexOf ( "," ) != -1 ) { //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 = 0; i < temparyip.Length; i++ ) { if ( IsIPAddress ( temparyip[i] ) && temparyip[i].Substring ( 0, 3 ) != "10." && temparyip[i].Substring ( 0, 7 ) != "192.168" && temparyip[i].Substring ( 0, 7 ) != "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 < 7 || str1.Length > 15 ) 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 ); } } }