What Is 444 Error Code |How Does It Work Comprehensive Guide With Examples

444 Error Code

What is 444 Error Code?

It is a unique status code of nginx that closes the connection without returning anything. In practical terms, encountering a 444 error means that the server is configured to block specific requests outright without providing any feedback to the client about why the request was denied. This can be a planned security measure to avoid unwanted or malicious traffic.

It is used when blocking access from malicious bots. When a request is made with an undefined host header in Nginx, the HTTP status code is written as 444.

 A  444 Error code is commonly associated with web servers, particularly the Nginx web server. In Nginx, a 444 error typically indicates that the server has closed the connection without sending any response to the client.

Here’s a breakdown:

  • 4: The first digit in the error code indicates a client error. This means the issue originates from the client making the request.
  • 44x: The “44x” range of status codes specifically pertains to errors related to the client’s request.
  • 444: This code in Nginx signifies that the server has closed the connection without responding to the client, effectively denying the request.

Example of [nginx]Status code “444

I created an environment with Docker and tried it out.

I wrote a setting that returns “444” when accessing /hoge.

nginx.conf

server {

    listen 80;

    listen [::]:80;

    server_name localhost;

    location / {

        root /usr/share/nginx/html;

        index index.html index.htm;

    }

    location = /hoge {

        return 444;

    }

}

$ curl localhost:8080/hoge

curl: (52) Empty reply from server

nothing returned from the server

How 444 status code works 

Suppose you have an Nginx web server configured to block requests from a specific IP address range (e.g., known for malicious activity). When a request comes from an IP address within that blocked range, Nginx might respond with a 444 error code, closing the connection without responding to the client.

Here’s a hypothetical scenario:

  • A client with the IP address 192.168.1.100 sends a request to access a resource on your Nginx server.
  • Your Nginx configuration includes a rule to block requests from the IP range 192.168.1.0/24.
  • Since the client’s IP address falls within the blocked range, Nginx immediately closes the connection without processing the request further.
  • Instead of receiving a response (e.g., the requested webpage), the client gets no data from the server, and the connection is terminated abruptly.
  • In the server logs, you might see an entry indicating that a request from 192.168.1.100 was denied with a “444” status code.

How to Identify 444 Error

If you encounter a “444 error” while browsing the web, the connection to the server abruptly closes without any response. This often happens for security reasons, like blocking suspicious requests or specific IP addresses.

  • Check Server Logs: Look for entries mentioning “444” in the server logs.
  • Watch Your Browser: If you see an error page or connection timeout, it might be a “444 error.”
  • Use Network Tools: Programs like Wireshark or Chrome DevTools can help spot sudden connection terminations.

How to resolve 444 Error Code?

Resolving a 444 error might not always be in your hands, but here’s what you can try:

  • Contact the Website Owner: If you can’t access a site due to a 444 error, reach out to the website’s support team.
  • Review Server Settings: If you manage the server, check its settings to ensure no rules trigger a 444 error.
  • Check Security Settings: Firewalls or security measures sometimes cause “444 errors.” Make sure they’re not blocking valid requests.

Understanding and fixing a  444 error can help keep your website accessible and secure.

This is just one example of how a “444” error code might occur in practice, typically due to server-side configurations designed to block or deny specific requests. If you’re wondering what 444 is, it‘s nginx’s specification.

I didn’t know there were non-standard HTTP status codes, and 444 is an unlucky number.

reference

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