java HttpServletRequest -- 获取请求主机真实的IP地址（摘抄整理）

短命女 2021-09-27 06:58 533阅读 0赞

在JSP里，获取客户端的IP地址的方法是：request.getRemoteAddr()，这种方法在大部分情况下都是有效的。但是在通过了 Apache，Nagix等反向代理软件就不能获取到客户端的真实IP地址了。如果使用了反向代理软件，用 request.getRemoteAddr()方法获取的IP地址是：127.0.0.1或 192.168.1.110，而并不是客户端的真实IP。

经过代理以后，由于在客户端和服务之间增加了中间层，因此服务器无法直接拿到客户端的 IP，服务器端应用也无法直接通过转发请求的地址返回给客户端。但是在转发请求的HTTP头信息中，增加了X-FORWARDED-FOR信息。用以跟踪原有的客户端 IP地址和原来客户端请求的服务器地址。

通过名字就知道，X-Forwarded-For 是一个 HTTP 扩展头部。HTTP/1.1（RFC 2616）协议并没有对它的定义，它最开始是由 Squid 这个缓存代理软件引入，用来表示 HTTP 请求端真实 IP。如今它已经成为事实上的标准，被各大 HTTP 代理、负载均衡等转发服务广泛使用，并被写入 RFC 7239（Forwarded HTTP Extension）标准之中。

X-Forwarded-For 请求头格式非常简单，就这样：

X-Forwarded-For: client, proxy1, proxy2

可以看到，XFF 的内容由「英文逗号 + 空格」隔开的多个部分组成，最开始的是离服务端最远的设备 IP，然后是每一级代理设备的 IP。

**request.getHeader("X-FORWARDED-FOR") 伪造这一字段非常容易，应该谨慎使用X-Forwarded-For字段**

**nginx 配置一**

proxy\_set\_header X-Real-IP $remote\_addr;

proxy\_set\_header X-Forwarded-For $proxy\_add\_x\_forwarded\_for;

public class IpUtils {
    
        private static final Logger logger = LoggerFactory.getLogger(IpUtils.class);
    
        public static final String _255 = "(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)";
    
        public static final Pattern pattern = Pattern.compile("^(?:" + _255 + "\\.){3}" + _255 + "$");
    
    
    
        public static String longToIpV4(long longIp) {
    
            int octet3 = (int) ((longIp >> 24) % 256);
    
            int octet2 = (int) ((longIp >> 16) % 256);
    
            int octet1 = (int) ((longIp >> 8) % 256);
    
            int octet0 = (int) ((longIp) % 256);
    
            return octet3 + "." + octet2 + "." + octet1 + "." + octet0;
    
        }
    
    
    
        public static long ipV4ToLong(String ip) {
    
            String[] octets = ip.split("\\.");
    
            return (Long.parseLong(octets[0]) << 24) + (Integer.parseInt(octets[1]) << 16)
    
                    + (Integer.parseInt(octets[2]) << 8) + Integer.parseInt(octets[3]);
    
        }
    
    
    
        public static boolean isIPv4Private(String ip) {
    
            long longIp = ipV4ToLong(ip);
    
            return (longIp >= ipV4ToLong("10.0.0.0") && longIp <= ipV4ToLong("10.255.255.255"))
    
                    || (longIp >= ipV4ToLong("172.16.0.0") && longIp <= ipV4ToLong("172.31.255.255"))
    
                    || longIp >= ipV4ToLong("192.168.0.0") && longIp <= ipV4ToLong("192.168.255.255");
    
        }
    
    
    
        public static boolean isIPv4Valid(String ip) {
    
            return pattern.matcher(ip).matches();
    
        }
    
    
    
        /**
    
         * 获取请求主机IP地址,如果通过代理进来，则透过防火墙获取真实IP地址;
    
         *
    
         * @param request
    
         * @return
    
         */
    
        public final static String getIpAddress(HttpServletRequest request) {
    
            logger.info("IpUtils.getIpAddress is start");
    
            if (request == null){
    
                logger.info("IpUtils.getIpAddress request is null");
    
                return null;
    
            }
    
    
    
            String headerType = "X-Forwarded-For";
    
            String ip = request.getHeader("X-Forwarded-For");
    
            if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                    headerType = "Proxy-Client-IP";
    
                    ip = request.getHeader("Proxy-Client-IP");
    
                }
    
                if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                    headerType = "WL-Proxy-Client-IP";
    
                    ip = request.getHeader("WL-Proxy-Client-IP");
    
                }
    
                if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                    headerType = "HTTP_CLIENT_IP";
    
                    ip = request.getHeader("HTTP_CLIENT_IP");
    
                }
    
                if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                    headerType = "HTTP_X_FORWARDED_FOR";
    
                    ip = request.getHeader("HTTP_X_FORWARDED_FOR");
    
                }
    
                if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
    
                    headerType = "getRemoteAddr";
    
                    ip = request.getRemoteAddr();
    
                }
    
            } else if (ip.length() > 15) {
    
                String[] ips = ip.split(",");
    
                for (int index = 0; index < ips.length; index++) {
    
                    String strIp = (String) ips[index];
    
                    if (!("unknown".equalsIgnoreCase(strIp))) {
    
                        ip = strIp;
    
                        break;
    
                    }
    
                }
    
            }
    
            logger.info("IpUtils.getIpAddress {} ip = {}",headerType,ip);
    
    
    
            if (isIPv4Valid(ip) && !isIPv4Private(ip)) {
    
                return ip;
    
            }
    
            return null;
    
        }
    
    }