How to Use Squid to Setup a Proxy Server or Load Balancer

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Squid is a popular open-source web proxy and caching server that can be used to set up a proxy server or load balancer. Here are the steps to set up Squid for these purposes:

Install Squid: On a Debian or Ubuntu-based system, use the command ‘sudo apt-get install squid’. On a Red Hat or Fedora-based system, use the command ‘sudo yum install squid’.

Configure Squid as a Proxy Server:

Open the Squid configuration file ‘squid.conf’ using a text editor and make the following changes:

• Uncomment the line ‘http_port 3128’ to listen on the default HTTP proxy port.
• Add the following line: ‘acl localnet src <ip-range>’ to specify the IP range of local networks.
• Add the following line: ‘http_access allow localnet’ to allow access to the local network.
• Save the changes and restart Squid using the command ‘sudo systemctl restart squid’.

Configure Squid as a Load Balancer:

To configure Squid as a load balancer, you need to add the following lines to the Squid configuration file ‘squid.conf’:

• Uncomment the line ‘http_port 80’ to listen on port 80.
• Add the following lines to specify the back-end servers:

cache_peer <backend-server-1-ip> parent 80 0 no-query default 
cache_peer <backend-server-2-ip> parent 80 0 no-query default

• Save the changes and restart Squid using the command ‘sudo systemctl restart squid’.

Test the Configuration: To test the configuration, set your browser’s proxy setting to use Squid’s IP address and port number. Try accessing a website and verify if it is being served by Squid.

In conclusion, Squid is a powerful and versatile tool that can be used to set up a proxy server or load balancer. The steps to set up Squid for these purposes are straightforward and can be easily followed.