How To Block IP Address on Nginx

Block IP Address on Nginx

In today’s digital landscape, web servers play a pivotal role in delivering content and services to users worldwide. Nginx, a popular open-source web server, is known for its speed and versatility. However, as your web applications gain popularity, they can become targets for malicious activities, making security a top priority. One effective way to enhance your Nginx server’s security is by blocking unwanted or potentially harmful IP addresses. In this comprehensive guide, we will walk you through the process of blocking IP addresses in Nginx using the command line, providing you with a robust defense against threats.

Understanding IP Address Blocking

The Concept of IP Address Blocking

IP address blocking is a security measure used to prevent access to your web server from specific IP addresses or ranges. By denying access to malicious or unwanted visitors, you can safeguard your server, enhance performance, and protect sensitive data.

Common Use Cases for IP Blocking in Nginx

1. Mitigating DDoS Attacks

  • Preventing attackers from overwhelming your server with a Distributed Denial of Service (DDoS) attack.

2. Blocking Malicious Bots

  • Identifying and blocking web crawlers or bots that scrape your content without permission.

3. Protecting Against Brute-Force Attacks

  • Defending your server against unauthorized access attempts by blocking IP addresses after repeated failed login attempts.

Benefits and Potential Drawbacks


  • Enhanced Security: Reducing the attack surface by blocking potentially harmful IPs.
  • Improved Performance: Decreasing server load by preventing unnecessary traffic.
  • Protection of Resources: Ensuring that your server resources are reserved for genuine users.

Potential Drawbacks:

  • False Positives: Blocking legitimate users accidentally.
  • Complexity: Managing and maintaining a growing list of blocked IPs can be challenging.

Preparing Your Nginx Environment

Before you start blocking IP addresses, ensure that your NGINX environment is set up correctly.

Ensuring Nginx is Installed

First, make sure NGINX is installed on your server. If it’s not, you can install it using the following commands:

# For Debian/Ubuntu #
sudo apt update
sudo apt install nginx

# For CentOS/RHEL #
sudo dnf install nginx

Accessing the Nginx Configuration File

NGINX’s configuration file is typically located at /etc/nginx/nginx.conf. You can edit it using your preferred text editor. Let’s use nano in this example:

sudo nano /etc/nginx/nginx.conf

Backup Your Nginx Configuration

Before making any changes, create a backup of your Nginx configuration file to easily revert to the previous state if something goes wrong:

sudo cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.bak

Identifying the Target IP Address

To effectively block IP addresses, you need to identify the ones you want to block. There are various methods to achieve this:

Methods for Tracking Malicious IP Addresses

1. Nginx Access Logs

  • Nginx logs can provide valuable information about incoming requests, including IP addresses. You can analyze these logs to spot suspicious or malicious activity.

2. Third-Party Tools

  • Utilize third-party security tools and services like Fail2Ban, ModSecurity, or intrusion detection systems (IDS) to help identify and block malicious IPs automatically.

Blocking IP Addresses Using NGINX Command Line

Now that you’ve prepared your Nginx environment and identified the target IP addresses, it’s time to block them using the command line.

Open the Nginx Configuration File

Open your Nginx configuration file with your text editor:

sudo nano /etc/nginx/nginx.conf

Syntax for Adding IP Address Blocks

In your NGINX configuration file, you can add IP address blocks within specific location blocks. To block an IP address, use the following syntax:

location / {
deny <IP_ADDRESS>;
# Add additional configuration if needed

Replace <IP_ADDRESS> with the actual IP address you want to block. For example, to block the IP address, your configuration might look like this:

location / {
# Add additional configuration if needed

Specifying Block Duration

You can specify whether the block is temporary or permanent:

  • Temporary Block: To block an IP temporarily, you can specify a time duration. For example, to block an IP for one hour, use:

location / {
# Block for 1 hour
  • Permanent Block: For a permanent block, simply add the IP to your configuration without specifying a time duration.

Testing Your Configuration for Syntax Errors

Before applying the changes, it’s essential to test your Nginx configuration for syntax errors. Use the following command:

sudo nginx -t

If there are no errors, you’ll see a message confirming that the configuration is valid. If there are issues, the command will provide information about the errors, allowing you to correct them.

Once your configuration passes the test, you can apply the following changes:

sudo systemctl reload nginx

Advanced Techniques for IP Blocking

Blocking IP addresses is not limited to basic configurations. You can employ advanced techniques to bolster your server’s security.

Creating Custom Response Pages for Blocked IPs

When an IP is blocked, you can customize the response they receive. For instance, you can create a custom HTML page explaining the reason for the block or redirecting them to a specific URL.

Blocking IP Ranges and CIDR Notation

To block multiple IPs efficiently, you can use CIDR (Classless Inter-Domain Routing) notation. For example, to block an entire IP range, you can use:

location / {
# Add additional configuration if needed

Using Regular Expressions to Block Multiple IPs

Regular expressions provide powerful pattern-matching capabilities. You can use them to block IPs that match specific criteria, such as a range of IP addresses or specific patterns in the IP.

Monitoring and Managing Blocked IP Addresses

Blocking IP addresses is not a one-time task; it requires ongoing management and monitoring.

Checking Nginx Error Logs

Regularly check Nginx error logs (/var/log/nginx/error.log) to ensure your IP blocking rules are working correctly and to identify any potential issues.

Whitelisting Trusted IPs

Don’t forget to whitelist trusted IP addresses, ensuring that you don’t accidentally block legitimate users or services. Place your whitelist rules before your block rules in the configuration file.

Automating IP Address Blocking with Scripts

Consider using scripts and automation to update your IP blocking rules dynamically. This can help you respond quickly to emerging threats.

Best Practices for IP Address Blocking

Maintaining a secure NGINX server involves adhering to best practices.

Keeping Your Nginx and Server Software Up to Date

Regularly update Nginx and your server’s operating system to patch security vulnerabilities and ensure you have the latest security features.

Regularly Reviewing and Maintaining Your Blocked IP List

Review your blocked IP list periodically to remove outdated entries and make adjustments based on evolving threats.

Collaborating with Security Tools and Threat Intelligence

Leverage security tools and threat intelligence feeds to stay informed about emerging threats and enhance your IP-blocking strategies.

Troubleshooting Common Issues

Despite your best efforts, issues may arise when implementing IP blocking. Here are common problems and solutions:

Addressing Misconfigured Rules

If you accidentally block legitimate traffic, review your Nginx configuration for errors, and adjust your rules accordingly.

Handling False Positives

If you encounter false positives where legitimate users are blocked, investigate the access logs to identify the cause and adjust your rules accordingly.


In an increasingly connected world, securing your Nginx web server is paramount. Blocking IP addresses using the command line provides a potent defense against various threats, from DDoS attacks to malicious bots. By following the steps outlined in this comprehensive guide, you can bolster your server’s security while ensuring that legitimate users continue to access your services uninterrupted.


r00t is a seasoned Linux system administrator with a wealth of experience in the field. Known for his contributions to, r00t has authored numerous tutorials and guides, helping users navigate the complexities of Linux systems. His expertise spans across various Linux distributions, including Ubuntu, CentOS, and Debian. r00t's work is characterized by his ability to simplify complex concepts, making Linux more accessible to users of all skill levels. His dedication to the Linux community and his commitment to sharing knowledge makes him a respected figure in the field.
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