How to obtain the user's real IP address based on nginx reverse proxy

引言

nginx做反向代理时，默认的配置后端获取到的Ip地址都来自于nginx，用request.getRemoteAddr();获取到的是nginx的ip地址,而不是用户的真实ip.

1.修改Nginx配置:

    server {
        listen       80;
        server_name  jenkins.local.com;
        location / {
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_pass http://192.168.10.204:8899;   
         }
         error_page   500 502 503 504  /50x.html;
         location = /50x.html {
            root   html;
            index  index.html index.htm index.jsp index.action default.html;
         }
           proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

在原来的基础配置上加上后三行配置，就可以使用request.getHeader(“x-forwarded-for”)来获取用户真实的Ip地址了

2.java获取客户端Ip

package com.zimax.cqyf.admin.util;

import javax.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;
 
/**
 * http工具类
 */
public class HttpUtils {
    /**
     * 获取真实的ip
     * @param request
     * @return
     * @throws UnknownHostException
     */
    public static String getRealIp(HttpServletRequest request){
        String ip;
        // 有的user可能使用代理，为处理用户使用代理的情况，使用x-forwarded-for
        if  (request.getHeader("x-forwarded-for") == null)  {
            ip = request.getRemoteAddr();
        }  else  {
            ip = request.getHeader("x-forwarded-for");
        }
        if  ("127.0.0.1".equals(ip))  {
            try {
                // 获取本机真正的ip地址
                ip = InetAddress.getLocalHost().getHostAddress();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        return ip;
    } 
}

附：一个ip工具类

import javax.servlet.http.HttpServletRequest;
/**
* IP地址工具类
* @author xudongdong
*
*/
public class IpUtil {
    
    /**
     * 私有化构造器
     */
    private IpUtil() {
    }
    /**
     * 获取真实IP地址
     * <p>使用getRealIP代替该方法</p>
     * @param request req
     * @return ip
     */
    @Deprecated
    public static String getClinetIpByReq(HttpServletRequest request) {
        // 获取客户端ip地址
        String clientIp = request.getHeader("x-forwarded-for");
        if (clientIp == null || clientIp.length() == 0 || "unknown".equalsIgnoreCase(clientIp)) {
            clientIp = request.getHeader("Proxy-Client-IP");
        }
        if (clientIp == null || clientIp.length() == 0 || "unknown".equalsIgnoreCase(clientIp)) {
            clientIp = request.getHeader("WL-Proxy-Client-IP");
        }
        if (clientIp == null || clientIp.length() == 0 || "unknown".equalsIgnoreCase(clientIp)) {
            clientIp = request.getRemoteAddr();
        }
        /*
         * 对于获取到多ip的情况下，找到公网ip.
         */
        String sIP = null;
        if (clientIp != null && !clientIp.contains("unknown") && clientIp.indexOf(",") > 0) {
            String[] ipsz = clientIp.split(",");
            for (String anIpsz : ipsz) {
                if (!isInnerIP(anIpsz.trim())) {
                    sIP = anIpsz.trim();
                    break;
                }
            }
            /*
             * 如果多ip都是内网ip，则取第一个ip.
             */
            if (null == sIP) {
                sIP = ipsz[0].trim();
            }
            clientIp = sIP;
        }
        if (clientIp != null && clientIp.contains("unknown")){
            clientIp =clientIp.replaceAll("unknown,", "");
            clientIp = clientIp.trim();
        }
        if ("".equals(clientIp) || null == clientIp){
            clientIp = "127.0.0.1";
        }
        return clientIp;
    }
    
    /**
     * 判断IP是否是内网地址
     * @param ipAddress ip地址
     * @return 是否是内网地址
     */
    public static boolean isInnerIP(String ipAddress) {
        boolean isInnerIp;
        long ipNum = getIpNum(ipAddress);
        /**   
        私有IP：A类  10.0.0.0-10.255.255.255   
               B类  172.16.0.0-172.31.255.255   
               C类  192.168.0.0-192.168.255.255   
        当然，还有127这个网段是环回地址   
        **/
        long aBegin = getIpNum("10.0.0.0");
        long aEnd = getIpNum("10.255.255.255");
        
        long bBegin = getIpNum("172.16.0.0");
        long bEnd = getIpNum("172.31.255.255");
        
        long cBegin = getIpNum("192.168.0.0");
        long cEnd = getIpNum("192.168.255.255");
        isInnerIp = isInner(ipNum, aBegin, aEnd) || isInner(ipNum, bBegin, bEnd) || isInner(ipNum, cBegin, cEnd)
                || ipAddress.equals("127.0.0.1");
        return isInnerIp;
    }
    private static long getIpNum(String ipAddress) {
        String[] ip = ipAddress.split("\\.");
        long a = Integer.parseInt(ip[0]);
        long b = Integer.parseInt(ip[1]);
        long c = Integer.parseInt(ip[2]);
        long d = Integer.parseInt(ip[3]);
        return a * 256 * 256 * 256 + b * 256 * 256 + c * 256 + d;
    }
    
    private static boolean isInner(long userIp, long begin, long end) {
        return (userIp >= begin) && (userIp <= end);
    }
    public static String getRealIP(HttpServletRequest request){
        // 获取客户端ip地址
        String clientIp = request.getHeader("x-forwarded-for");
        if (clientIp == null || clientIp.length() == 0 || "unknown".equalsIgnoreCase(clientIp)) {
            clientIp = request.getRemoteAddr();
        }
        String[] clientIps = clientIp.split(",");
        if(clientIps.length <= 1) return clientIp.trim();
        // 判断是否来自CDN
        if(isComefromCDN(request)){
            if(clientIps.length>=2) return clientIps[clientIps.length-2].trim();
        }
        return clientIps[clientIps.length-1].trim();
    }
    private static boolean isComefromCDN(HttpServletRequest request) {
        String host = request.getHeader("host");
        return host.contains("www.189.cn") ||host.contains("shouji.189.cn") || host.contains(
                "image2.chinatelecom-ec.com") || host.contains(
                "image1.chinatelecom-ec.com");
    }
}

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