how to detect search engine bots with php?

Question

How can one detect the search engine bots using php?

Answer 1

I use the following code which seems to be working fine:

function _bot_detected() {

  return (
    isset($_SERVER['HTTP_USER_AGENT'])
    && preg_match('/bot|crawl|slurp|spider|mediapartners/i', $_SERVER['HTTP_USER_AGENT'])
  );
}

update 16-06-2017 https://support.google.com/webmasters/answer/1061943?hl=en

added mediapartners

Answer 2

Check the $_SERVER['HTTP_USER_AGENT'] for some of the strings listed here:

http://www.useragentstring.com/pages/All/

Or more specifically for crawlers:

http://www.useragentstring.com/pages/Crawlerlist/

If you want to -say- log the number of visits of most common search engine crawlers, you could use

$interestingCrawlers = array( 'google', 'yahoo' );
$pattern = '/(' . implode('|', $interestingCrawlers) .')/';
$matches = array();
$numMatches = preg_match($pattern, strtolower($_SERVER['HTTP_USER_AGENT']), $matches, 'i');
if($numMatches > 0) // Found a match
{
  // $matches[1] contains an array of all text matches to either 'google' or 'yahoo'
}

Answer 3

You can checkout if it's a search engine with this function :

<?php
function crawlerDetect($USER_AGENT)
{
$crawlers = array(
'Google' => 'Google',
'MSN' => 'msnbot',
      'Rambler' => 'Rambler',
      'Yahoo' => 'Yahoo',
      'AbachoBOT' => 'AbachoBOT',
      'accoona' => 'Accoona',
      'AcoiRobot' => 'AcoiRobot',
      'ASPSeek' => 'ASPSeek',
      'CrocCrawler' => 'CrocCrawler',
      'Dumbot' => 'Dumbot',
      'FAST-WebCrawler' => 'FAST-WebCrawler',
      'GeonaBot' => 'GeonaBot',
      'Gigabot' => 'Gigabot',
      'Lycos spider' => 'Lycos',
      'MSRBOT' => 'MSRBOT',
      'Altavista robot' => 'Scooter',
      'AltaVista robot' => 'Altavista',
      'ID-Search Bot' => 'IDBot',
      'eStyle Bot' => 'eStyle',
      'Scrubby robot' => 'Scrubby',
      'Facebook' => 'facebookexternalhit',
  );
  // to get crawlers string used in function uncomment it
  // it is better to save it in string than use implode every time
  // global $crawlers
   $crawlers_agents = implode('|',$crawlers);
  if (strpos($crawlers_agents, $USER_AGENT) === false)
      return false;
    else {
    return TRUE;
    }
}
?>

Then you can use it like :

<?php $USER_AGENT = $_SERVER['HTTP_USER_AGENT'];
  if(crawlerDetect($USER_AGENT)) return "no need to lang redirection";?>

Answer 4

Here's a Search Engine Directory of Spider names

Then you use $_SERVER['HTTP_USER_AGENT']; to check if the agent is said spider.

if(strstr(strtolower($_SERVER['HTTP_USER_AGENT']), "googlebot"))
{
    // what to do
}

Answer 5

I'm using this code, pretty good. You will very easy to know user-agents visitted your site. This code is opening a file and write the user_agent down the file. You can check each day this file by go to yourdomain.com/useragent.txt and know about new user_agents and put them in your condition of if clause.

$user_agent = strtolower($_SERVER['HTTP_USER_AGENT']);
if(!preg_match("/Googlebot|MJ12bot|yandexbot/i", $user_agent)){
    // if not meet the conditions then
    // do what you need

    // here open a file and write the user_agent down the file. You can check each day this file useragent.txt and know about new user_agents and put them in your condition of if clause
    if($user_agent!=""){
        $myfile = fopen("useragent.txt", "a") or die("Unable to open file useragent.txt!");
        fwrite($myfile, $user_agent);
        $user_agent = "\n";
        fwrite($myfile, $user_agent);
        fclose($myfile);
    }
}

This is the content of useragent.txt

Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Mozilla/5.0 (compatible; MJ12bot/v1.4.6; http://mj12bot.com/)Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)mozilla/5.0 (compatible; yandexbot/3.0; +http://yandex.com/bots)
mozilla/5.0 (compatible; yandexbot/3.0; +http://yandex.com/bots)
mozilla/5.0 (compatible; yandexbot/3.0; +http://yandex.com/bots)
mozilla/5.0 (compatible; yandexbot/3.0; +http://yandex.com/bots)
mozilla/5.0 (compatible; yandexbot/3.0; +http://yandex.com/bots)
mozilla/5.0 (iphone; cpu iphone os 9_3 like mac os x) applewebkit/601.1.46 (khtml, like gecko) version/9.0 mobile/13e198 safari/601.1
mozilla/5.0 (windows nt 6.1; wow64) applewebkit/537.36 (khtml, like gecko) chrome/53.0.2785.143 safari/537.36
mozilla/5.0 (compatible; linkdexbot/2.2; +http://www.linkdex.com/bots/)
mozilla/5.0 (windows nt 6.1; wow64; rv:49.0) gecko/20100101 firefox/49.0
mozilla/5.0 (windows nt 6.1; wow64; rv:33.0) gecko/20100101 firefox/33.0
mozilla/5.0 (windows nt 6.1; wow64; rv:49.0) gecko/20100101 firefox/49.0
mozilla/5.0 (windows nt 6.1; wow64; rv:33.0) gecko/20100101 firefox/33.0
mozilla/5.0 (windows nt 6.1; wow64; rv:49.0) gecko/20100101 firefox/49.0
mozilla/5.0 (windows nt 6.1; wow64; rv:33.0) gecko/20100101 firefox/33.0
mozilla/5.0 (windows nt 6.1; wow64; rv:49.0) gecko/20100101 firefox/49.0
mozilla/5.0 (windows nt 6.1; wow64; rv:33.0) gecko/20100101 firefox/33.0
mozilla/5.0 (windows nt 6.1; wow64) applewebkit/537.36 (khtml, like gecko) chrome/53.0.2785.143 safari/537.36
mozilla/5.0 (windows nt 6.1; wow64) applewebkit/537.36 (khtml, like gecko) chrome/53.0.2785.143 safari/537.36
mozilla/5.0 (compatible; baiduspider/2.0; +http://www.baidu.com/search/spider.html)
zoombot (linkbot 1.0 http://suite.seozoom.it/bot.html)
mozilla/5.0 (windows nt 10.0; wow64) applewebkit/537.36 (khtml, like gecko) chrome/44.0.2403.155 safari/537.36 opr/31.0.1889.174
mozilla/5.0 (windows nt 10.0; wow64) applewebkit/537.36 (khtml, like gecko) chrome/44.0.2403.155 safari/537.36 opr/31.0.1889.174
sogou web spider/4.0(+http://www.sogou.com/docs/help/webmasters.htm#07)
mozilla/5.0 (windows nt 10.0; wow64) applewebkit/537.36 (khtml, like gecko) chrome/44.0.2403.155 safari/537.36 opr/31.0.1889.174

Answer 6

I use this function ... part of the regex comes from prestashop but I added some more bot to it.

    public function isBot()
{
    $bot_regex = '/BotLink|bingbot|AhrefsBot|ahoy|AlkalineBOT|anthill|appie|arale|araneo|AraybOt|ariadne|arks|ATN_Worldwide|Atomz|bbot|Bjaaland|Ukonline|borg\-bot\/0\.9|boxseabot|bspider|calif|christcrawler|CMC\/0\.01|combine|confuzzledbot|CoolBot|cosmos|Internet Cruiser Robot|cusco|cyberspyder|cydralspider|desertrealm, desert realm|digger|DIIbot|grabber|downloadexpress|DragonBot|dwcp|ecollector|ebiness|elfinbot|esculapio|esther|fastcrawler|FDSE|FELIX IDE|ESI|fido|H�m�h�kki|KIT\-Fireball|fouineur|Freecrawl|gammaSpider|gazz|gcreep|golem|googlebot|griffon|Gromit|gulliver|gulper|hambot|havIndex|hotwired|htdig|iajabot|INGRID\/0\.1|Informant|InfoSpiders|inspectorwww|irobot|Iron33|JBot|jcrawler|Teoma|Jeeves|jobo|image\.kapsi\.net|KDD\-Explorer|ko_yappo_robot|label\-grabber|larbin|legs|Linkidator|linkwalker|Lockon|logo_gif_crawler|marvin|mattie|mediafox|MerzScope|NEC\-MeshExplorer|MindCrawler|udmsearch|moget|Motor|msnbot|muncher|muninn|MuscatFerret|MwdSearch|sharp\-info\-agent|WebMechanic|NetScoop|newscan\-online|ObjectsSearch|Occam|Orbsearch\/1\.0|packrat|pageboy|ParaSite|patric|pegasus|perlcrawler|phpdig|piltdownman|Pimptrain|pjspider|PlumtreeWebAccessor|PortalBSpider|psbot|Getterrobo\-Plus|Raven|RHCS|RixBot|roadrunner|Robbie|robi|RoboCrawl|robofox|Scooter|Search\-AU|searchprocess|Senrigan|Shagseeker|sift|SimBot|Site Valet|skymob|SLCrawler\/2\.0|slurp|ESI|snooper|solbot|speedy|spider_monkey|SpiderBot\/1\.0|spiderline|nil|suke|http:\/\/www\.sygol\.com|tach_bw|TechBOT|templeton|titin|topiclink|UdmSearch|urlck|Valkyrie libwww\-perl|verticrawl|Victoria|void\-bot|Voyager|VWbot_K|crawlpaper|wapspider|WebBandit\/1\.0|webcatcher|T\-H\-U\-N\-D\-E\-R\-S\-T\-O\-N\-E|WebMoose|webquest|webreaper|webs|webspider|WebWalker|wget|winona|whowhere|wlm|WOLP|WWWC|none|XGET|Nederland\.zoek|AISearchBot|woriobot|NetSeer|Nutch|YandexBot|YandexMobileBot|SemrushBot|FatBot|MJ12bot|DotBot|AddThis|baiduspider|SeznamBot|mod_pagespeed|CCBot|openstat.ru\/Bot|m2e/i';
    $userAgent = empty($_SERVER['HTTP_USER_AGENT']) ? FALSE : $_SERVER['HTTP_USER_AGENT'];
    $isBot = !$userAgent || preg_match($bot_regex, $userAgent);

    return $isBot;
}

Anyway take care that some bots uses browser like user agent to fake their identity
( I got many russian ip that has this behaviour on my site )

One distinctive feature of most of the bot is that they don't carry any cookie and so no session is attached to them.
( I am not sure how but this is for sure the best way to track them )