What is a Squid Proxy Cache Server? (Features Explained)

What is a Squid Proxy Cache Server?.  Ever since the day the Internet was made public, there’s been a constant race to achieve the fastest connection speeds possible. Many methods have been adopted towards achieving consecutively quicker speeds – one of them is with the help of proxy cache servers. And, among such servers, we find the Squid Proxy Cache Server.

Squid Proxy Cache server
The rate of increase of Internet speeds

In this post, we will have a look at what a Squid Proxy Cache Server is, how it helps improve your Internet connection, as well as the other advantages that come with using it.

First… what is a Cache Server?

A cache server redirects request objects from clients, made from their browsers to the server. When the requested objects arrive from the server, it both delivers the objects to the client and also keeps a copy of them in the hard disk cache.

One advantage of caching requested objects is that several clients requesting the same object can be served from the hard disk cache – instead of having to go back again and retrieving it from the source. This enables clients to receive the data more quickly than they would if it would have to be fetched from the source server. Another advantage is the reduction of network traffic.

Squid Proxy Cache Securing and Caching Internet Access

Ok; so, what is a Squid Proxy Cache Server?

A Squid Proxy Cache Server is a caching server that also acts as a forward proxy. Once Squid Proxy Server is installed on a network, the clients’ web browsers can be configured to use it as an HTTP proxy server which allows Squid to cache copies of the request results returned to them. When requests are repeated for the same results it is then served to the client from the cached copies and not from the original data source. This results in reduced access time as well as lower bandwidth consumption.

Advantages of a Squid Proxy Cache Server

Deploying a Squid Proxy Server has a wide range of advantages, some of which are:

  • Caching web – speeding up a web server by caching repeated requests so requests are handled locally instead of heading out to the source.
  • Domain Name System (DNS) server – Squid Proxy Cache Server can be used as a DNS server that helps resolve hostnames either via the built-in internal DNS client or with the help of third-party DNS applications.
  • Security tool – Squid also helps in increasing network security by filtering incoming traffic; external clients won’t be able to pass through the proxy without authorization while malicious websites won’t be able to attack any users that may have stumbled onto some malicious code.
  • Load sharing – in case of a traffic surge or unexpected bandwidth clogging (perhaps backups are being done) Squid Proxy can be configured to distribute loads over intercommunicating hierarchies of proxy servers which helps in faster response times and decongestion of traffic.
  • Authentication – Squid can be configured to define an Access Control List (ACL) which sets the permissions for who can access the proxy resources.
  • Corporate censorship – Squid also acts like a proxy server that allows or denies access to specific websites; the permissions can also be configured depending on the time of the workday.
  • Using reports – Squid Proxy generates reports that can be used as input for scaling, security, and resource planning; for example, the statistics about frequently-visited websites that can be used to assess users’ surfing habits. They can even use third-party software like Grafana for even more detailed reports.
Grafana Squid Report dashboard
A Grafana report with a Squid data source

Protocols supported by Squid Proxy Cache Server

We have just seen that an instance of a Squid Proxy Cache Server can serve as a cache, proxy, and DNS server. Now, let’s have a look at the protocols it supports.

Squid Proxy mainly caters to Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP) protocols for caching, proxy, and DNS services. But, it also offers limited support for other protocols like Hypertext Transfer Protocol Secure (HTTPS), Transport Layer Security (TLS), Secure Sockets Layer (SSL), and Internet Gopher.

Although Squid does not support the SOCKS protocol it can be paired with third-party applications like Privoxy if support for the protocol is required.

Where can I get Squid?

First, a little bit of trivia: Squid was originally designed to run as a daemon on Unix-like systems and now also ships with many Linux or UNIX flavors while a Windows port was maintained up to version 2.7 and newer versions are available on Windows (and must use the Cygwin environment).

But, right now Squid Proxy Cache Server is a free software solution, released under the GNU General Public License, and can be downloaded at the official Squid Cache website. The site offers various versions that can be downloaded from various mirrors located worldwide.

Squid Proxy Cache Server Security Considerations

Finally, let’s have a look at some points to consider during and after the installation of a Squid Proxy Cache Server:

  • Squid should be installed on a secure, dedicated server – it would defeat the whole purpose of installing a proxy server if it were accessible to anyone who would want to bypass or even hack it; it should be considered as a security device and treated as such.
  • Secure the Squid server itself – although it is in itself a security system, a Squid Proxy Cache Server should itself be protected. Antiviruses and anti-malware should be installed to protect it, for example.
  • Remove UNIX bloatware – administrators should remove any services they have no intention of using as they may be targeted for exploitation, and hence, pose a security risk to the Squid Proxy Cache Server itself. UNIX systems usually come with services that may not be used; it would make perfect sense to disable any services that are never used.
  • Use a sandbox account – administrators should create a sandbox user that is specially created for the Squid Proxy installation; any login attempts using this user account should trigger an alarm (thus, indicating a hacking attempt).
  • Squid should integrate into the network’s security – that’s right, although Squid does serve as a security system, it doesn’t mean it should be the only one protecting the network. Instead, it should integrate into other network security systems (like SIEM, IPS, and DLP tools, for example) seamlessly.
  • Keep logging feature on – although system or event logs and audit trails can eat up into storage resources, it would still be a mistake to turn them off. In the case of Squid, it offers peering capabilities to share the traffic loads while investing in extra storage devices is also a good idea.
  • Make use of reports – there is a large selection of analyzers listed on the Squid scripts site that can be used as both free and highly insightful reports that show usage, warnings, and even failure data – all of which are critical tools for administrators.

Always use professionals for Squid Proxy Cache Server installations

On a closing note – we have seen that there are some risks posed when a Squid Proxy Cache Server is being installed, and even when it is up and running – just like with any production server.

And so, our advice here would be that you hire or work with professionals who know how to protect your data, speed up your connections, as well as configure the new Squid Proxy Cache Server so it performs at optimal levels.

Avatar for Liku Zelleke
Liku Zelleke

Liku Zelleke is a technology blogger who has over two decades experience in the IT industry. He hasn’t looked back since the day, years ago, when he discovered he could combine that experience with his other passion: writing. Today, he writes on topics related to network configuration, optimization, and security for Cloud Infrastructure Services.

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