如何在servlet中获取客户端的远程地址？

Question

有什么办法可以让客户端的原始IP地址进入服务器吗？我可以使用request.getRemoteAddr()，但我似乎总是得到代理或Web服务器的IP。

我想知道客户端用来连接我的IP地址。无论如何我能得到它吗？

Answer 1

试试这个：

public static String getClientIpAddr(HttpServletRequest request) {  
        String ip = request.getHeader("X-Forwarded-For");  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("Proxy-Client-IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("WL-Proxy-Client-IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_CLIENT_IP");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");  
        }  
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {  
            ip = request.getRemoteAddr();  
        }  
        return ip;  
    }  

Answer 2

InetAddress inetAddress = InetAddress.getLocalHost();
String ip = inetAddress.getHostAddress();

Answer 3

request.getRemoteAddr()就是这样。您的代理似乎更改了源IP。当某些代理执行此操作时，他们会在某些自定义http标头中添加原始IP。使用request.getHeaderNames()和request.getHeaders(name)并打印所有这些以查看是否没有任何感兴趣的内容。像X-CLIENT-IP（做了一个，但他们看起来像这样）

Answer 4

我用过的最好的解决方案

public String getIpAddr(HttpServletRequest request) {      
   String ip = request.getHeader("x-forwarded-for");      
   if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {      
       ip = request.getHeader("Proxy-Client-IP");      
   }      
   if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {      
       ip = request.getHeader("WL-Proxy-Client-IP");      
   }      
   if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {      
       ip = request.getRemoteAddr();      
   }      
   return ip;      
} 

Answer 5

你不能以有意义的方式做到这一点。

代理可能会也可能不会添加代理头，但在很多情况下，这将是一个内部唯一的地址，所以对你来说没有意义。组织边缘的大多数代理都被配置为尽可能少地揭示网络的内部结构。

您打算将这些信息用于什么？

Answer 6

由于这通常是部署问题，而不是应用程序问题，另一种方法是适当地配置应用程序容器。配置完成后，容器会负责检查相应的标题，您的应用程序将继续使用request.getRemoteAddr()。

例如，在Tomcat中，您可以使用Remote IP Valve。我认为大多数应用服务器都具有类似的功能。

如果您的前端负载均衡器正在终止SSL连接，并通过HTTP将请求转发到应用服务器，则容器还可以了解情况。当您的应用程序需要为自己生成URL时，这很重要。

Answer 7

如果使用代理或负载均衡器，“x-forwarded-for”请求标头包含原始客户端IP。但我认为并非所有代理/ lb都添加此标头。

这里有一些解析标题的java代码：http://www.codereye.com/2010/01/get-real-ip-from-request-in-java.html

如果这个标题不存在，那么我会像@Bozho建议的那样继续

Answer 8

String ipAddress = request.getHeader("x-forwarded-for");
        if (ipAddress == null) {
            ipAddress = request.getHeader("X_FORWARDED_FOR");
            if (ipAddress == null){
                ipAddress = request.getRemoteAddr();
            }
        }

Answer 9

为什么不使用这样更优雅的解决方案？

private static final List<String> IP_HEADERS = Arrays.asList("X-Forwarded-For", "Proxy-Client-IP", "WL-Proxy-Client-IP", "HTTP_CLIENT_IP", "HTTP_X_FORWARDED_FOR");

public static String getClientIpAddr(HttpServletRequest request) {
    for (String ipHeader : IP_HEADERS) {
        String ip = request.getHeader(ipHeader);
        if (ip != null && !ip.isEmpty() && !ip.equalsIgnoreCase("unknown")) {
            return ip;
        }
    }
    return request.getRemoteAddr();
}

重复编码你的代码！

Answer 10

为什么我认为我们应该首先尝试从标题'X-Forwarded-For'获取IP？如果你从request.getRemoteAddr()，它可能是client's real ip or last proxy's ip which forwards the request。因此，我们无法分辨它属于哪种情况。但是，如果将'X-Forwarded-For'设置到标头中，则客户端IP必然是您从中获取的最左侧部分。

    /**
     * Try to get real ip from request:
     * <ul>
     *     <li>try X-Forwarded-For</li>
     *     <li>try remote address</li>
     * </ul>
     *
     * @param request    request
     * @return real ip or ""
     */
    private String tryGetRealIp(HttpServletRequest request) {
        // X-Forwarded-For: <client>, <proxy1>, <proxy2>
        // If a request goes through multiple proxies, the IP addresses of each successive proxy is listed.
        // This means, the right-most IP address is the IP address of the most recent proxy and
        // the left-most IP address is the IP address of the originating client.
        String forwards = request.getHeader("X-Forwarded-For");
        if (StringUtils.isNotBlank(forwards)) {
            // The left-most IP must be client ip
            String ip = StringUtils.substringBefore(forwards, ",");
            return ip;
        } else if (StringUtils.isNotBlank(request.getRemoteAddr())) {
            // this could be real client ip or last proxy ip which forwards the request
            return request.getRemoteAddr();
        }
        return "";
    }