How to Configure a Squid Proxy to Listen on Multiple Ports

Squid is a caching and forwarding web proxy. It is most often used in conjunction with a traditional LAMP stack (Linux, Apache, MySQL, PHP), and can be used to filter traffic on HTTP, FTP, and HTTPS, and increase the speed (thus lower the response time) for a web server via caching.

• These instructions are intended specifically for configuring a Squid Proxy to listen on multiple ports.
• In this case I’ll be working from a Liquid Web Core Managed CentOS 7 server, and I’ll be logged in as root.

By default, Squid launches a session listening on port 3128.

Running the command:

netstat -plant

Should show something similar to:

Proto  Recv-Q  Send-Q  Local Address  Foreign Address  State  PID/Program name
tcp6   0       0       :::3128        :::*             LISTEN 6261/(squid-1)

Where :::3128 is the port on which Squid is listening.

Configuration file locations may vary. The config file should be called squid.conf. To find the config file use the following command:

locate squid.conf

You should receive a result similar to:

/etc/squid/squid.conf

For a refresher on editing files with vim see: New User Tutorial: Overview of the Vim Text Editor

Now, let’s edit the file found in the previous step:

vim /etc/squid/squid.conf

Look for a section of the configuration file similar to:

# Squid normally listens to port 3128
http_port 3128

Each port number on which you’d like Squid to listen requires a separate line in the config file.

For example: to use port 1337 and 1338 edit the file to include:

http_port 1337
http_port 1338

Exit and save the file, and then restart Squid:

systemctl restart squid

Now running the command:

netstat -plant

Should show something similar to:

Proto  Recv-Q  Send-Q  Local Address  Foreign Address  State  PID/Program name
tcp6   0       0       :::1337        :::*             LISTEN 6261/(squid-1)
tcp6   0       0       :::1338        :::*             LISTEN 6261/(squid-1)

Where :::1337 and :::1338 are the ports on which Squid is listening.