BUUCTF2018-OnlineTool

​ 今日心情不佳，整道ctf题

<?php

if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_FORWARDED_FOR'];
} #这里是让服务器获取ip的，没啥用

if(!isset($_GET['host'])) {
    highlight_file(__FILE__); #如果没有设定host参数，就给咱看代码
} else {
    $host = $_GET['host'];
    $host = escapeshellarg($host);
    $host = escapeshellcmd($host);
    $sandbox = md5("glzjin". $_SERVER['REMOTE_ADDR']);
    echo 'you are in sandbox '.$sandbox;
    @mkdir($sandbox);
    chdir($sandbox);
    echo system("nmap -T5 -sT -Pn --host-timeout 2 -F ".$host);
}

拿到代码先注释一下，下面放一下新学到的这俩函数吧