What are some common challenges faced when using PHP to crawl websites behind strict firewalls?

When using PHP to crawl websites behind strict firewalls, a common challenge is that the firewall may block the requests made by the PHP script, resulting in failed crawling attempts. To solve this, you can try setting custom headers in your PHP script to mimic a regular browser request, which may help bypass the firewall restrictions. 

<?php
$url = 'https://example.com';

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);

if($response === false){
    echo 'Error: ' . curl_error($ch);
} else {
    echo $response;
}

curl_close($ch);
?>

Keywords

firewall website crawling PHP cURL authentication

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