Squid Proxy Server

Name: Squid Proxy Server
Rating: 4.3 (123 reviews)

How to configure Squid Proxy Server, Filter Web Traffic, Authentication and Transparent Proxy

Created byVipin Gupta

Last updated 1/2026

English

What you'll learn

How to configure Squid Proxy Server and setup clients
How to use Access Control Lists (ACLs)
How to control access on basis of source IP addresses, destination domains, words, day and time, MAC addresses etc.
How to configure Squid Authentication
How to setup Transparent Proxy
How to setup squid proxy server lab

Course content

7 sections • 38 lectures • 4h 1m total length

Course Overview2:07
Explore the Squid proxy server, its caching and access control features, and how to configure a lab with Windows and Linux clients to implement authentication and transparent proxy.
Squid Proxy Server Lab Setup Details3:36
if you are facing issues regarding "yum" not working, please refer to lecture 38 for troubleshooting.
Verify Squid Proxy Server Lab Setup Settings7:56

How to Configure Squid Proxy Server Introduction10:13
Start Proxy Server and test internet connectivity5:50
Configuring Proxy Settings on Linux Client Running in GUI Mode6:14
Configure firefox proxy settings on a linux c11 system to use squid at 172.24.0.1:3128, then set temporary and permanent proxies by exporting six environment variables including http_proxy via config file.
Configuring Proxy Settings on Linux Client Running in CLI Mode6:03
Configuring Proxy Settings on Windows Client3:19
Configure proxy settings on the Windows Edge browser by enabling the open proxy settings, entering the proxy address 172.24.0.1 and port 3128, and saving to access pages.

Squid ACL Introduction. What is the purpose of Default ACL7:42
Learn how squid proxy acl controls access by source, destination, and time, using http_access with named acls to allow or deny, and understand default localnet and wildcard mask concepts.
Create ACL for allowing access to a particular network. Verify using clients.8:11
Modify squid.conf to replace the default localnet ACL with a new mynetwork ACL for source 172.24.0.0/16, then apply http_access rules and restart squid to verify access from clients.
Deny Access from a particular system. Create/Verify the ACL.5:54
Deny Access from particular IP range. Create/Verify the ACL.4:27
Configure a squid proxy ACL named bbb to deny internet access for hosts from 172.24.0.11 to 172.24.0.21/32, then verify with targeted tests and restart the squid server.
Deny Access from a particular network. Create/Verify the ACL.4:16
Create an ACL named lab1 to deny the 172.24.0.0/16 network. Apply http_access deny lab1 and then allow all, and verify access on C11, C21, and C30.
How to block websites. Create/Verify ACL.6:33
Block websites by creating a destination domain acl (dstdomain) in squid, listing domains like .fb.com, linuxexpert.in, and .ca, then use http_access deny, http_access allow all, and verify across systems.
Block access on basis of particular words. Create and Verify ACL.6:19
Create and verify a Squid acl named badwords with dstdom_regex to block sites containing words like adult and chat, using -i for case insensitivity, and deny while allowing others.
Block access on basis of particular words. Use file for words.2:38

Control Access based on Type of file the user is trying to access.7:46
Create an acl badfiles in Squid using urlpath_regex with ignore case to block downloads of certain file types (exe, mov, iso, dat, avi), reducing bandwidth.
Allow/Deny Access based on time and day7:40
Block Access to certain types of files from a particular system. Combine ACLs.6:09
Demonstrate combining acl rules in squid to block specific file types for a single system using an aaa acl and badfiles, via http_access deny with an and condition.
Allow access to certain types of files during particular duration. Combine ACLs.6:44
Control access on basis of MAC Address5:53
Block access by mac address with an acl named maclist using arp, then http_access deny maclist and allow; you can combine acl types such as domain, src, urlpath, and time.

Squid Proxy Server Authentication Introduction4:14
Learn how squid proxy server authentication restricts access to authenticated users using basic_ncsa_auth from /usr/lib64/squid/ and an httpd-style password file in /etc/squid/users, with squid.conf edits and user setup.
How to Configure Squid Proxy Server Authentication7:11
Configure CLI mode proxy setting. Verify authentication is working or not.11:53
Configure squid proxy authentication for Aanya and Nanu, test access in Firefox and Edge, adjust CLI and Elinks settings, verify curl works, then revert to original configuration.

Configure Transparent Proxy9:45
Configure transparent proxy with squid and iptables to redirect traffic without browser changes. Enable ip forwarding and set http_port 3128 in squid.conf, then configure NAT to route 80 to 3128.
Verify Transparent Proxy using Linux Client Running in GUI Mode7:18
Verify transparent proxy on linux gui client by removing proxy settings, configuring gateway 172.24.0.1 and dns servers 8.8.8.8 and 8.8.4.4, restarting network, and validating access to websites.
Verify Transparent Proxy using Linux Client Running in CLI Mode3:01
Remove proxy configurations from profile.d and Firefox, reboot to test in text mode, verify no proxy is set, access sites with elinks, and review environment and resolv.conf settings.
Verify Transparent Proxy using Linux Client Running in CLI Mode. Troubeshoot.3:50
Configure gateway and DNS on Linux CLI, verify proxy settings with grep, restart the network service, and test access to secure sites to confirm the transparent proxy is functioning.
Verify Transparent Proxy using Windows Client3:11
Verify transparent proxy on a Windows client by disabling browser proxy settings, configuring ipv4 172.24.0.1 and dns 8.8.8.8, and accessing sites without browser changes using squid with iptables.
Dismantle Transparent Proxy Lab3:51
Dismantle a transparent proxy by flushing NAT rules, resetting sysctl and squid settings, saving changes, and restarting network services on c21, c11, and c30 systems.

CentOS Linux Installation14:56
Post Installation Settings8:38
Perform post installation settings by disabling SELinux and the firewalld service, installing and enabling iptables, and configuring NAT for VM internet access. Configure a static IP via /etc/sysconfig/network-scripts/ifcfg-ens33.
Create Squid Proxy Server VM10:40
learn to create a squid proxy server vm, clone it for a lab, configure two network interfaces, install squid and httpd-tools, and set static and dynamic IPs.
Create Linux Client VM with GUI7:40
Clone a CentOS 7 machine to create C11 with gui by installing GNOME desktop, enabling graphical boot, and setting hostname to C11.example.com with a static IP 172.24.0.11 on bridged networking.
Create Linux Client VM with CLI Mode2:59
Clone a linux client vm as a full clone named c21, assign a static ip and hostname, bridge networking, reboot, and verify connectivity by pinging the server.
install Windows 108:23
Test Connectivity from Windows System3:43
Test connectivity from Windows C30 by pinging 172.24.0.1 and verifying 172.24.0.30 with subnet 255.255.0.0 using ipconfig, in a lab with GUI mode and elinks.
Yum Update Troubleshooting5:12
Backup Current Repository Configuration:
First, make a backup of your current repository configuration files.

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

Edit the Repository Configuration:
Open the CentOS-Base.repo file in a text editor. (vi or nano)

nano /etc/yum.repos.d/CentOS-Base.repo

Update the Base Repository URLs:

Replace the existing base repository URLs with the URLs pointing to the CentOS Vault. The updated configuration should look something like this:

[base]
name=CentOS-$releasever - Base
baseurl=http://vault.centos.org/7.9.2009/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

[updates]
name=CentOS-$releasever - Updates
baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

[extras]
name=CentOS-$releasever - Extras
baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

Save the Changes:

Save the changes and exit the text editor (Ctrl+X, Y, Enter for nano).

Clean YUM Cache:

Clean the YUM cache to ensure it uses the updated repository configuration.

yum clean all
yum makecache

Update the System:

Now you can update your system using the Vault repositories.

yum update

This should allow you to continue using yum with the archived CentOS 7 repositories.
Course Quiz

Requirements

Basic Linux Knowledge

Description

Squid proxy server is used for internet sharing. It is one of the most widely used, very robust and powerful server. It also provides access control (ACLs) and caching. It improves response time and reduces bandwidth usage.

* Squid Proxy Server Introduction

* How to configure Squid Proxy Server and setup clients

* How to use Access Control Lists (ACLs). Different types of acls

* How to control access on basis of source IP addresses, destination domains, words, day and time, MAC addresses etc.

* How to combine various types of ACLs to fine tune access.

* How to configure Squid Authentication. How to verify whether authentication is working properly or not.

* How to setup Transparent Proxy. Setting up transparent proxy involves combining squid and iptables. What are the different settings that needs to be configured. How to access transparent proxy. What are the settings that needs to be made on client systems.

* How to setup Squid Proxy Server Lab. Squid proxy server lab consists of 4 systems. One Linux system with 2 network interface cards will act as proxy server. One NIC will will be used to connect to internet and other will be used to connect to local area network. Remaining 3 systems (2 Linux and 1 Windows) will act as squid proxy clients.

* How to configure proxy server settings in different GUI based browsers.

* How to configure CLI proxy settings.

Who this course is for:

Anyone who wants to learn squid proxy server

Squid Proxy Server

What you'll learn

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Course content