剛剛測試程序，一個功能要求獲取客戶端IP，然而在本機測試過程中發現，客戶端(本機)IP始終返回::1，獲取 IP 部份的代碼如下：
private string GetIP()
{
string result = String.Empty;
result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (null == result || result == String.Empty)
{
result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
}
if (null == result || result == String.Empty)
{
result = HttpContext.Current.Request.UserHostAddress;
}
if (null == result || result == String.Empty || !IsIP(result))
{
result = "0.0.0.0";
}
return result;
}
public static bool IsIP(string ip)
{
return Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
}
於是最終獲取倒的是因無法匹配而返回的默認IP 0.0.0.0
google了一下，沒有結果。
繼續想辦法。發現不影響獲取其它客戶端（非本機）IP。根據此現象，我想應該是localhost引起的，於是查看host映射，果然發現::1
(Host映射查看方法 C:\Windows\System32\drivers\etc 文件hosts)
# Copyright (c) 1993-2006 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 sosoft.cnblogs.com # source server
# 38.25.63.10 roucheng.cnblogs.com # x client host
127.0.0.1 localhost
::1 localhost
原來是因為操作系統開啟了IPV6，它對localhost進行了映射的原因。如果我們需要獲取的IP是IPV4的，那麼可以刪掉::1映射。
如果將來我們需要獲取的是IPV6的IP，那麼就需要這樣的映射。然後程序裡統一實現獲取IPv6的代碼。
或者：
1。Dns.GetHostByName("").AddressList[0].ToString();
或
2、 string localIP = "";
foreach (IPAddress ip in Dns.GetHostAddresses(""))
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
localIP = ip.ToString();
}
}
