How to Install Squid to Configure a Proxy Server on AlmaLinux

Proxy servers play a vital role in managing and optimizing network traffic, improving security, and controlling internet access. One of the most popular tools for setting up a proxy server is Squid, an open-source, high-performance caching proxy. Squid supports various protocols like HTTP, HTTPS, and FTP, making it ideal for businesses, educational institutions, and individuals seeking to improve their network’s efficiency.

This guide provides a step-by-step process to install and configure Squid Proxy Server on AlmaLinux.

What is Squid Proxy Server?

Squid Proxy Server acts as an intermediary between client devices and the internet. It intercepts requests, caches content, and enforces access policies. Some of its key features include:

• Web caching: Reducing bandwidth consumption by storing frequently accessed content.
• Access control: Restricting access to certain resources based on rules.
• Content filtering: Blocking specific websites or types of content.
• Enhanced security: Hiding client IP addresses and inspecting HTTPS traffic.

With Squid, network administrators can optimize internet usage, monitor traffic, and safeguard network security.

Benefits of Setting Up a Proxy Server with Squid

Implementing Squid Proxy Server offers several advantages:

1. Bandwidth Savings: Reduces data consumption by caching repetitive requests.
2. Improved Speed: Decreases load times for frequently visited sites.
3. Access Control: Manages who can access specific resources on the internet.
4. Enhanced Privacy: Masks the client’s IP address from external servers.
5. Monitoring: Tracks user activity and provides detailed logging.

Prerequisites for Installing Squid on AlmaLinux

Before proceeding with the installation, ensure:

1. You have a server running AlmaLinux with sudo or root access.
2. Your system is updated.
3. Basic knowledge of terminal commands and networking.

Step 1: Update AlmaLinux

Begin by updating your system to ensure all packages and dependencies are up to date:

sudo dnf update -y

Step 2: Install Squid

Install Squid using the default package manager, dnf:

sudo dnf install squid -y

Verify the installation by checking the version:

squid -v

Once installed, Squid’s configuration files are stored in the following locations:

• Main configuration file: /etc/squid/squid.conf
• Access logs: /var/log/squid/access.log
• Cache logs: /var/log/squid/cache.log

Step 3: Start and Enable Squid

Start the Squid service:

sudo systemctl start squid

Enable Squid to start on boot:

sudo systemctl enable squid

Check the service status to confirm it’s running:

sudo systemctl status squid

Step 4: Configure Squid

Squid’s behavior is controlled through its main configuration file. Open it with a text editor:

sudo nano /etc/squid/squid.conf

Step 4.1: Define Access Control Lists (ACLs)

Access Control Lists (ACLs) specify which devices or networks can use the proxy. Add the following lines to allow specific IP ranges:

acl localnet src 192.168.1.0/24
http_access allow localnet

Replace 192.168.1.0/24 with your local network’s IP range.

Step 4.2: Change the Listening Port

By default, Squid listens on port 3128. You can change this by modifying:

http_port 3128

For example, to use port 8080:

http_port 8080

Step 4.3: Configure Caching

Set cache size and directory to optimize performance. Locate the cache_dir directive and adjust the settings:

cache_dir ufs /var/spool/squid 10000 16 256

• ufs is the storage type.
• /var/spool/squid is the cache directory.
• 10000 is the cache size in MB.

Step 4.4: Restrict Access to Specific Websites

Block websites by adding them to a file and linking it in the configuration:

1. Create a file for blocked sites:

   sudo nano /etc/squid/blocked_sites.txt
   

2. Add the domains you want to block:

   example.com
   badsite.com
   

3. Reference this file in squid.conf:

   acl blocked_sites dstdomain "/etc/squid/blocked_sites.txt"
   http_access deny blocked_sites
   

Step 5: Apply Changes and Restart Squid

After making changes to the configuration file, restart the Squid service to apply them:

sudo systemctl restart squid

Verify Squid’s syntax before restarting to ensure there are no errors:

sudo squid -k parse

Step 6: Configure Clients to Use the Proxy

To route client traffic through Squid, configure the proxy settings on client devices.

For Windows:

1. Open Control Panel > Internet Options.
2. Navigate to the Connections tab and click LAN settings.
3. Check the box for Use a proxy server and enter the server’s IP address and port (e.g., 3128).

For Linux:

Set the proxy settings in the network manager or use the terminal:

export http_proxy="http://<server-ip>:3128"
export https_proxy="http://<server-ip>:3128"

Step 7: Monitor Squid Proxy Logs

Squid provides logs that help monitor traffic and troubleshoot issues. Use these commands to view logs:

• Access logs:

  sudo tail -f /var/log/squid/access.log
  

• Cache logs:

  sudo tail -f /var/log/squid/cache.log
  

Logs provide insights into client activity, blocked sites, and overall proxy performance.

Step 8: Enhance Squid with Authentication

Add user authentication to restrict proxy usage. Squid supports basic HTTP authentication.

1. Install the required package:

   sudo dnf install httpd-tools -y
   

2. Create a password file and add users:

   sudo htpasswd -c /etc/squid/passwd username
   

   Replace username with the desired username. You’ll be prompted to set a password.

3. Configure Squid to use the password file. Add the following lines to squid.conf:

   auth_param basic program /usr/lib64/squid/basic_ncsa_auth /etc/squid/passwd
   auth_param basic children 5
   auth_param basic realm Squid Proxy
   auth_param basic credentialsttl 2 hours
   acl authenticated proxy_auth REQUIRED
   http_access allow authenticated
   

4. Restart Squid to apply the changes:

   sudo systemctl restart squid
   

Now, users will need to provide a username and password to use the proxy.

Step 9: Test Your Proxy Server

Use a web browser or a command-line tool to test the proxy:

curl -x http://<server-ip>:3128 http://example.com

Replace <server-ip> with your server’s IP address. If the proxy is working correctly, the page will load through Squid.

Advanced Squid Configurations

1. SSL Interception

Squid can intercept HTTPS traffic for content filtering and monitoring. However, this requires generating and deploying SSL certificates.

2. Bandwidth Limitation

You can set bandwidth restrictions to ensure fair usage:

delay_pools 1
delay_class 1 2
delay_parameters 1 64000/64000 8000/8000
delay_access 1 allow all

3. Reverse Proxy

Squid can act as a reverse proxy to cache and serve content for backend web servers. This improves performance and reduces server load.

Conclusion

Setting up a Squid Proxy Server on AlmaLinux is a straightforward process that can significantly enhance network efficiency, security, and control. By following this guide, you’ve learned how to install, configure, and optimize Squid for your specific needs.

Whether you’re managing a corporate network, school, or personal setup, Squid provides the tools to monitor, secure, and improve internet usage.