获取nginx转发前的真实ip

有时，需要获取客户端真实ip，但由于nginx转发后，已经不是真实ip地址

解决方式如下：在你的nginx配置下加上如下配置即可

  	location /{
  
        proxy_pass http://127.0.0.1:8080;//转发到你的业务服务器服务器
        proxy_set_header x-forwarded-for  $remote_addr;//把真实ip设置到请求头里面

      }

主要是：

proxy_set_header x-forwarded-for  $remote_addr;//把真实ip设置到请求头里面

说明：

REMOTE_ADDR

表示发出请求的远程主机的 IP 地址，remote_addr代表客户端的IP，但它的值不是由客户端提供的，而是服务端根据客户端的ip指定的，当你的浏览器访问某个网站时，假设中间没有任何代理，那么网站的web服务器（Nginx，Apache等）就会把remote_addr设为你的机器IP，如果你用了某个代理，那么你的浏览器会先访问这个代理，然后再由这个代理转发到网站，这样web服务器就会把remote_addr设为这台代理机器的IP

x_forwarded_for

简称XFF头，它代表客户端，也就是HTTP的请求端真实的IP，只有在通过了HTTP 代理或者负载均衡服务器时才会添加该项，正如上面所述,当你使用了代理时,web服务器就不知道你的真实IP了,为了避免这个情况,代理服务器通常会增加一个叫做x_forwarded_for的头信息,把连接它的客户端IP(即你的上网机器IP)加到这个头信息里,这样就能保证网站的web服务器能获取到真实IP

二、服务端java方式获取ip代码：

    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_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_CLUSTER_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_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_FORWARDED");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_VIA");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("REMOTE_ADDR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;