编程：获取IP，判断是否为北京的IP

我的目标是获取IP，判断是北京的IP的话，就进入一个页
怎么写呀？
if Request.ServerVariables("REMOTE_ADDR") 是北京段 then
这里涉及到北京的IP段的数据库。
高分友情大家予以协助。

<%
Function lookaddress(sip)
Dim str1, str2, str3, str4
Dim num
Dim irs
If IsNumeric(Left(sip, 2)) Then
If sip = "127.0.0.1" Then sip = "192.168.0.1"
str1 = Left(sip, InStr(sip, ".") - 1)
sip = Mid(sip, InStr(sip, ".") + 1)
str2 = Left(sip, InStr(sip, ".") - 1)
sip = Mid(sip, InStr(sip, ".") + 1)
str3 = Left(sip, InStr(sip, ".") - 1)
str4 = Mid(sip, InStr(sip, ".") + 1)
If IsNumeric(str1) = 0 Or IsNumeric(str2) = 0 Or IsNumeric(str3) = 0 Or IsNumeric(str4) = 0 Then
Else
num = cdbl(str1) * 16777216 + cdbl(str2) * 65536 + cdbl(str3) * 256 + cdbl(str4) - 1
sql = "select timezone from IPaddress where startip <=" & num & " and endip >=" & num
Set irs = conn.Execute(sql)
If irs.EOF And irs.BOF Then
lookaddress = "0"
Else
Do While Not irs.EOF
lookaddress = irs(0)
irs.MoveNext
Loop
End If
irs.Close
Set irs = Nothing
End If
Else
lookaddress = "0"
End If
End Function
userip = Request.ServerVariables("HTTP_X_FORWARDED_FOR")
If userip = "" Then userip = Request.ServerVariables("REMOTE_ADDR")
visitflag = lookaddress(userip)
if visitflag = "" then
Response.Write("window.location.href=' http:/www.goimage.cn';")
elseif visitflag="010"
Response.Write("window.location.href='http:/bj.goimage.cn';")
end if
%>
数据库结构：
表名：IPaddress
startip: 起始IP
endip: 结束IP
country: 所在位置
timezone: 电话区号（这里根据电话区号做判断，分站可以做到县级）

using System.Net; IPAddress addr = new IPAddress(Dns.GetHostByName(Dns.GetHostName()).AddressList[0].Address); string newIP= addr.ToString();//首先获得本地IP

if(newIP==北京IP)

{

ClientScript.RegisterStartupScript(typeof(string), "", "<script>alert('IP相同，跳转页面');href='newpage.aspx'</script>");

}

else

{

ClientScript.RegisterStartupScript(typeof(string), "", "<script>alert('IP不是北京的IP')</script>");

}

1、先把北京的所有IP记录在数据库中

2、程序获取客户端的IP，同数据库中对比，要用循环或者in

自己有数据库查询

或者利用网络 从别人的网站上查 获取结果 显示在你那