springboot通过禁用异常访问IP的方式抵挡DDos攻击

1.基本原理

        DDos攻击原理就是短时间发动大量正常的网站访问占用服务器资源，造成服务器卡顿，或失去连接。通过将异常访问服务器的IP禁止访问，或延时访问可以一定程度的减轻DDos攻击强度。

2.springboot程序实现

2.1 先编写一个过滤器

/**
 * @author SongBin on 2021-11-08.
 */
package com.mtons.mblog.web.filter;

import com.mtons.mblog.base.utils.IPUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
 * 自定义过滤器，用来判断IP访问次数是否超限
 * 如果前台用户访问网站的频率过快（达到超过50次/秒），则判定该ip恶意刷新操作，
 * 限制该IP的访问，1小时后自己解除限制
 *
 * @author wukaikai
 *
 */
@WebFilter(urlPatterns="/*")
public class IpFilter implements Filter{
    protected final Logger logger = LoggerFactory.getLogger(this.getClass());
    /**
     * 默认限制时间-被限制多长时间（单位：ms）
     */
    private static final long LIMITED_TIME_MILLIS = 60 * 60 * 1000; //限制1小时

    /**
     * 用户连续访问最高阀值，超过该值则认定为恶意操作的IP，进行限制
     */
    private static final int LIMIT_NUMBER = 50;

    /**
     * 用户访问最小安全时间，在该时间内如果访问次数大于阀值，则记录为恶意IP，否则视为正常访问
     */
    private static final int MIN_SAFE_TIME = 5000;//判定5s内访问超过50次，为恶意访问
    private FilterConfig config;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.config = filterConfig;    //设置属性filterConfig
    }

    /* (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    @SuppressWarnings("unchecked")
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        ServletContext context = config.getServletContext();
        // 获取限制IP存储器：存储被限制的IP信息
        Map<String, Long> limitedIpMap = (Map<String, Long>) context.getAttribute("limitedIpMap");
        // 过滤受限的IP
        filterLimitedIpMap(limitedIpMap);
        // 获取用户IP
        String ip = IPUtils.getRemoteIpAddr(request);
        logger.debug("ip:"+ip);
        // 判断是否是被限制的IP，如果是则跳到异常页面
        if (isLimitedIP(limitedIpMap, ip)) {
            long limitedTime = limitedIpMap.get(ip) - System.currentTimeMillis();
            // 剩余限制时间(用为从毫秒到秒转化的一定会存在些许误差，但基本可以忽略不计)
            request.setAttribute("remainingTime", ((limitedTime / 1000) + (limitedTime % 1000 > 0 ? 1 : 0)));
            //request.getRequestDispatcher("/error/overLimitIP").forward(request, response);
            logger.error("ip访问过于频繁1："+ip);
            response.setContentType("text/html;charset=UTF-8");
            request.setCharacterEncoding("UTF-8");
            response.setCharacterEncoding("UTF-8");  //设置输出内容编码格式
            PrintWriter out = response.getWriter();
            out.println("<b>由于您访问过于频繁，被系统自动认定为机器人。1个小时自动解除</b>");
            return;
        }
        // 获取IP存储器
        Map<String, Long[]> ipMap = (Map<String, Long[]>) context.getAttribute("ipMap");
        // 判断存储器中是否存在当前IP，如果没有则为初次访问，初始化该ip
        // 如果存在当前ip，则验证当前ip的访问次数
        // 如果大于限制阀值，判断达到阀值的时间，如果不大于[用户访问最小安全时间]则视为恶意访问，跳转到异常页面
        if (ipMap.containsKey(ip)) {
            Long[] ipInfo = ipMap.get(ip);
            ipInfo[0] = ipInfo[0] + 1;
            logger.debug("当前第[" + (ipInfo[0]) + "]次访问");
            if (ipInfo[0] > LIMIT_NUMBER) {
                Long ipAccessTime = ipInfo[1];
                Long currentTimeMillis = System.currentTimeMillis();
                if (currentTimeMillis - ipAccessTime <= MIN_SAFE_TIME) {
                    limitedIpMap.put(ip, currentTimeMillis + LIMITED_TIME_MILLIS);
                    request.setAttribute("remainingTime", LIMITED_TIME_MILLIS);
                    logger.error("ip访问过于频繁2："+ip);
                    request.getRequestDispatcher("/error/overLimitIP").forward(request, response);
                    return;
                } else {
                    initIpVisitsNumber(ipMap, ip);
                }
            }
        } else {
            initIpVisitsNumber(ipMap, ip);
            logger.debug("您首次访问该网站");
        }
        context.setAttribute("ipMap", ipMap);
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @Description 过滤受限的IP，剔除已经到期的限制IP
     * @param limitedIpMap
     */
    private void filterLimitedIpMap(Map<String, Long> limitedIpMap) {
        if (limitedIpMap == null) {
            return;
        }
        Set<String> keys = limitedIpMap.keySet();
        Iterator<String> keyIt = keys.iterator();
        long currentTimeMillis = System.currentTimeMillis();
        while (keyIt.hasNext()) {
            long expireTimeMillis = limitedIpMap.get(keyIt.next());
            if (expireTimeMillis <= currentTimeMillis) {
                keyIt.remove();
            }
        }
    }

    /**
     * @Description 是否是被限制的IP
     * @param limitedIpMap
     * @param ip
     * @return true : 被限制 | false : 正常
     */
    private boolean isLimitedIP(Map<String, Long> limitedIpMap, String ip) {
        if (limitedIpMap == null || ip == null) {
            // 没有被限制
            return false;
        }
        Set<String> keys = limitedIpMap.keySet();
        Iterator<String> keyIt = keys.iterator();
        while (keyIt.hasNext()) {
            String key = keyIt.next();
            if (key.equals(ip)) {
                // 被限制的IP
                return true;
            }
        }
        return false;
    }

    /**
     * 初始化用户访问次数和访问时间
     *
     * @param ipMap
     * @param ip
     */
    private void initIpVisitsNumber(Map<String, Long[]> ipMap, String ip) {
        Long[] ipInfo = new Long[2];
        ipInfo[0] = 0L;// 访问次数
        ipInfo[1] = System.currentTimeMillis();// 初次访问时间
        ipMap.put(ip, ipInfo);
    }

}

不懂得看日志，基本能够看懂，看不懂就放弃吧！

2.2 IP获取工具类

package com.mtons.mblog.base.utils;

import org.apache.commons.lang3.StringUtils;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class IPUtils {
    public static String getRemoteHost() {
        ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        if (servletRequestAttributes == null) {
            return "127.0.0.1";
        }

        HttpServletRequest request = servletRequestAttributes.getRequest();
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("x-real-ip");
        }
        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();
        }
        if ("0:0:0:0:0:0:0:1".equals(ip)) {
            ip = "127.0.0.1";
        }
        return ip;
    }

    public static String getRemoteIpAddr(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();
            if("127.0.0.1".equals(ip)||"0:0:0:0:0:0:0:1".equals(ip)){
                //根据网卡取本机配置的IP
                InetAddress inet=null;
                try {
                    inet = InetAddress.getLocalHost();
                } catch (UnknownHostException e) {
                    e.printStackTrace();
                }
                ip= inet.getHostAddress();
            }
        }
        return ip;
    }

    /**
     * 判断IP是否在指定范围
     *
     * @param ipStart
     * @param ipEnd
     * @param ip
     * @return
     */
    public static boolean ipIsValid(String ipStart, String ipEnd, String ip) {
        if (StringUtils.isEmpty(ipStart)) {
            throw new NullPointerException("起始IP不能为空！");
        }
        if (StringUtils.isEmpty(ipEnd)) {
            throw new NullPointerException("结束IP不能为空！");
        }
        if (StringUtils.isEmpty(ip)) {
            throw new NullPointerException("IP不能为空！");
        }
        ipStart = ipStart.trim();
        ipEnd = ipEnd.trim();
        ip = ip.trim();
        final String REGX_IP = "((25[0-5]|2[0-4]\\d|1\\d{2}|[1-9]\\d|\\d)\\.){3}(25[0-5]|2[0-4]\\d|1\\d{2}|[1-9]\\d|\\d)";
        final String REGX_IPB = REGX_IP + "\\-" + REGX_IP;
        if (!ipStart.matches(REGX_IP) || !ip.matches(REGX_IP) || !ipEnd.matches(REGX_IP)) {
            return false;
        }
        String[] sips = ipStart.split("\\.");
        String[] sipe = ipEnd.split("\\.");
        String[] sipt = ip.split("\\.");
        long ips = 0L, ipe = 0L, ipt = 0L;
        for (int i = 0; i < 4; ++i) {
            ips = ips << 8 | Integer.parseInt(sips[i]);
            ipe = ipe << 8 | Integer.parseInt(sipe[i]);
            ipt = ipt << 8 | Integer.parseInt(sipt[i]);
        }
        if (ips > ipe) {
            long t = ips;
            ips = ipe;
            ipe = t;
        }
        return ips <= ipt && ipt <= ipe;
    }
}

2.3 创建一个监听器：需要初始化俩个容器：

/**
 * @author SongBin on 2021-11-08.
 */
package com.mtons.mblog.web.listener;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@WebListener
public class MyApplicationListener implements ServletContextListener {
    private Logger logger =  LoggerFactory.getLogger(MyApplicationListener.class);
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        logger.info("liting: contextInitialized");
        System.err.println("MyApplicationListener初始化成功");
        ServletContext context = sce.getServletContext();
        // IP存储器
        Map<String, Long[]> ipMap = new HashMap<String, Long[]>();
        context.setAttribute("ipMap", ipMap);
        // 限制IP存储器：存储被限制的IP信息
        Map<String, Long> limitedIpMap = new HashMap<String, Long>();
        context.setAttribute("limitedIpMap", limitedIpMap);
        logger.info("ipmap："+ipMap.toString()+";limitedIpMap:"+limitedIpMap.toString()+"初始化成功。。。。。");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        // TODO Auto-generated method stub

    }
}

注意：需要在springboot启动类里面添加以上监听器和过滤器的扫描包路径：

@ServletComponentScan(basePackages="com.mtons.mblog.web")

注意：本文归作者所有，未经作者允许，不得转载