NetcraftSurveyAgent
Netcraft •
Since 1995
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Official Docs
What is NetcraftSurveyAgent?
NetcraftSurveyAgent is operated by Netcraft, a British internet security services company known for their Web Server Survey and anti-phishing services. The bot performs internet-wide scans to detect phishing sites, malware distribution, and gather statistics about web technologies. Netcraft's data powers various security products and their monthly Web Server Survey has tracked internet growth since 1995. The crawler helps identify fraudulent websites and provides early warning of cyber threats.
User Agent String
Mozilla/5.0 (compatible; NetcraftSurveyAgent/1.0; [email protected])
How to Control NetcraftSurveyAgent
Block Completely
To prevent NetcraftSurveyAgent from accessing your entire website, add this to your robots.txt file:
# Block NetcraftSurveyAgent
User-agent: NetcraftSurveyAgent
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: NetcraftSurveyAgent
Disallow: /admin/
Disallow: /private/
Disallow: /wp-admin/
Allow: /public/
Set Crawl Delay
To slow down the crawl rate (note: not all bots respect this directive):
User-agent: NetcraftSurveyAgent
Crawl-delay: 10
How to Verify NetcraftSurveyAgent
Verification Method:
Netcraft's published information
Netcraft's published information
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect NetcraftSurveyAgent in your application:
Basic Pattern
/NetcraftSurveyAgent/i
Strict Pattern
/^Mozilla/5\.0 \(compatible; NetcraftSurveyAgent/1\.0; \+info@netcraft\.com\)$/
Flexible Pattern
/NetcraftSurveyAgent[\s\/]?[\d\.]*?/i
Vendor Match
/.*Netcraft.*NetcraftSurveyAgent/i
Implementation Examples
// PHP Detection for NetcraftSurveyAgent
function detect_netcraftsurveyagent() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/NetcraftSurveyAgent/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('NetcraftSurveyAgent detected from IP: ' . $_SERVER['REMOTE_ADDR']);
// Set cache headers
header('Cache-Control: public, max-age=3600');
header('X-Robots-Tag: noarchive');
// Optional: Serve cached version
if (file_exists('cache/' . md5($_SERVER['REQUEST_URI']) . '.html')) {
readfile('cache/' . md5($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for NetcraftSurveyAgent
import re
from flask import request, make_response
def detect_netcraftsurveyagent():
user_agent = request.headers.get('User-Agent', '')
pattern = r'NetcraftSurveyAgent'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False
# Django Middleware
class NetcraftSurveyAgentMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for NetcraftSurveyAgent
const express = require('express');
const app = express();
// Middleware to detect NetcraftSurveyAgent
function detectNetcraftSurveyAgent(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /NetcraftSurveyAgent/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('NetcraftSurveyAgent detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'NetcraftSurveyAgent';
}
next();
}
app.use(detectNetcraftSurveyAgent);
# Apache .htaccess rules for NetcraftSurveyAgent
# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} NetcraftSurveyAgent [NC]
RewriteRule .* - [F,L]
# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} NetcraftSurveyAgent [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]
# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "NetcraftSurveyAgent" is_bot=1
# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /NetcraftSurveyAgent/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for NetcraftSurveyAgent
# Map user agent to variable
map $http_user_agent $is_netcraftsurveyagent {
default 0;
~*NetcraftSurveyAgent 1;
}
server {
# Block the bot completely
if ($is_netcraftsurveyagent) {
return 403;
}
# Or serve cached content
location / {
if ($is_netcraftsurveyagent) {
root /var/www/cached;
try_files $uri $uri.html $uri/index.html @backend;
}
try_files $uri @backend;
}
# Add headers for bot requests
location @backend {
if ($is_netcraftsurveyagent) {
add_header Cache-Control "public, max-age=3600";
add_header X-Robots-Tag "noarchive";
}
proxy_pass http://backend;
}
}
Should You Block This Bot?
Recommendations based on your website type:
| Site Type | Recommendation | Reasoning |
|---|---|---|
| E-commerce | Optional | Evaluate based on bandwidth usage vs. benefits |
| Blog/News | Allow | Increases content reach and discoverability |
| SaaS Application | Block | No benefit for application interfaces; preserve resources |
| Documentation | Selective | Allow for public docs, block for internal docs |
| Corporate Site | Limit | Allow for public pages, block sensitive areas like intranets |
Advanced robots.txt Configurations
E-commerce Site Configuration
User-agent: NetcraftSurveyAgent
Crawl-delay: 5
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Disallow: /api/
Disallow: /*?sort=
Disallow: /*?filter=
Disallow: /*&page=
Allow: /products/
Allow: /categories/
Sitemap: https://example.com/sitemap.xml
Publishing/Blog Configuration
User-agent: NetcraftSurveyAgent
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: NetcraftSurveyAgent
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
NetcraftSurveyAgent
Robots.txt Name
NetcraftSurveyAgent
Category
security, other
Respects robots.txt
Yes
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