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Best cloud firewall in 2021

A person at a laptop with a secure lock symbol floating above it.
(Image credit: Shutterstock / laymanzoom)

The best cloud firewall software makes it simple and easy to protect your desktop and mobile devices against unauthorized intrusions and hacking attacks.

The best cloud firewalls

Also known as Web Application Firewalls (WAF), these are becoming an increasingly integral part of cybersecurity protections on IT networks, as a way to ring-fence and protect business networks against malicious third-party attacks. These attacks can range from anything from Distributed Denial of Service (DDoS) attacks to direct hacking activity, to malware infiltration and exfiltration.

While ordinary users might commonly use a firewall as either a standalone software program or as part of an antivirus software package, setting up a firewall for business applications can be much more of a challenge.

Fora start, businesses need to avoid false positives, especially where that might involve legitimate customers being blocked from the products or services they are entitled to. Additionally, with the increasing use of smartphones on business IT networks the surface area for attacks has grown with the number of devices in use. TechRadar Exclusive
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There's also the need to ensure that IT staff aren't force to spend their time chasing these false positives and so increase the likelihood that a real attack will be overlooked.

While there are cloud antivirus platforms as well as endpoint security and employee monitoring, all intending to help improve IT security, a cloud firewall aims to ensure a general protective shell around IT systems.

Ransomware attacks, phishing, credential stuffing, and clickjacking, are additional issues that Web Application Firewalls aim to prevent and protect against. However, a WAF should be invisible to users, so they will never know it's there. Usually, WAFs come with dynamic rules that are constantly updated to keep abreast of the latest threats, along with a backend dashboard to provide analytics of how it's working.

There are a number of WAFs on the market, and here we'll look at some of the best available now. 


(Image credit: CloudFlare)

1. CloudFlare WAF

The advanced cloud WAF

Reasons to buy
+Market leader+Customizable rules+Free tier

CloudFlare is a company that provides content delivery services, DDoS mitigation, Internet security and distributed domain name server providers. 

The solution monitors the internet on a regular basis for any new updates such as attacks and vulnerabilities. Anything that is considered a threat to the majority of their clients automatically have WAF (Web application Firewalls) rules enabled. These will protect all internet properties. Constant updates ensure that CloudFlare’s protection is in place at all times.

Cloudflare deals with a huge number of requests every hour with the solution identifying and blocking new threats. Due to their large customer base, the platform is able to rely on a collective intelligence when it comes to eradicating threats. This means that when one customer creates a new WAF rule, CloudFlare decides whether it applies to all other domains on their network.

CloudFlare has a free tier. This includes unmetered mitigation of DDoS, global CDN, shared SSL certificate and 3 page rules. Additional rules can be purchased through CloudFlare’s dashboard.


(Image credit: AWS)


Amazon's cloud services firewall

Reasons to buy
+Easy to use+Free tier+Minimal setup

Amazon Web Services is part of It provides on-demand cloud computing platforms to individuals and businesses. As part of this subscription, users have access to AWS WAF

AWS WAF is a web application firewall which protects web applications from threats which could compromise their security or consume resources. The solution itself is straight forward and easy to use. 

Users can create custom made rules designed to block common attack patterns such as cross-site scripting. The solution has a full featured API which allows users to automate the creation, deployment and maintenance of all rules in use.

AWS WAF works by charging you for each new rule you create. You are not charged a set price every month but you do have to be subscribed to Amazon Web Services to access this feature.


(Image credit: Sophos)

3. Sophos Firewall

Dedicated cloud security

Reasons to buy
+Multiple security features+30-day free trial
Reasons to avoid
-Some UI issues

Sophos is a British security software and hardware company. It develops products for communication endpoint, encryption, network security and unified threat management.

Sophos Firewall is a unified threat manager which also acts as application security and wireless gateway.

Users can manage settings from Sophos’ ‘Control Center’. From here subscribers  can access the utilities dashboard. This allows you to view your network, users and applications. You can also add Sophos ‘iView’. This provides centralized reporting across multiple firewalls.

The management interface gives users an overview on features such as traffic insights, system statistics and firewall rules.

Sophos offers users a 30-day free trial. This includes IPS, ATP, Sandboxing, Dual AV, Web and App Control, Anti-phishing and Web Application Firewall. Subscribers need to contact Sophos directly to receive a quote.


(Image credit: Akamai)

4. Akamai Kona Site Defender

Akamai’s firewall and DDoS protection

Reasons to buy
+Built-in DDoS protection+Intuitive dashboard
Reasons to avoid
-Full product information not on site

Akamai Kona Site Defenderr integrates DDoS protection with its web application firewall. DDoS services identify and neutralize threats from IP addresses by using a scale system from 1 to 10. These scores are based on the IP addresses ability to source suspicious traffic. Scores are then used to allow, alert or block based on the severity of the score. Users can also customize settings so they can choose which IP addresses they want blocked.

The web application firewall inspects individual traffic. Any malicious attacks are eradicated. This tool only works against web-based attacks. Users can use the management dashboard to access information such as reports and attack rates. The utility requires very little customization.

Subscribers will need to contact Akamai directly in order to start their free trial and to get a quote.


(Image credit: Imperva)

5. Imperva WAF

Imperva is a digital swiss army knife of security tools

Reasons to buy
+Free trial+Multiple security features
Reasons to avoid
-Not competitively priced

Imperva offers a cloud-based Web Application Firewall (WAF).  It provides application delivery with content caching and load balancing through a global content delivery network, advanced bot protection, API security, web application security and DDoS mitigation.

The Imperva Web Application Firewall works as a gateway for all traffic coming to your online services. It filters out malicious visitors and requests such as SQL injections and XSS attacks.

The solution uses several layers of security policies to identify threats. These are maintained by a security team. Imperva uses attack information from their network to provide protection for their users.

Imperva has 45 DDoS scrubbing data centers around the world which ensures 24/7 monitoring.

To get a quote or begin a free trial, interested parties should contact Imperva directly.


(Image credit: Signal Sciences)

6. Signal Sciences WAF

Next generation cloud firewall protection

Reasons to buy
+Quick deployment+Flexible use+Easy management

Signal Sciences was founded five years ago by the security developers at Etsy, and since then the company has grown and developed with a string of high-profile clients.

A key promotional point of the Signal Sciences WAF is that too many existing services don't properly service modern IT infrastructures, especially where there is extensive use of cloud technology, as opposed to being reliant on legacy hardware.

Setting up is so easy and quick it can be done in minutes, as there are no agents to deploy with all traffic being redirected through the Signal Services Cloud Engine, where it can be monitored and filtered as required.

There's a single management console with built-in analytics that provides real-time monitoring, so there's no need to work through multiple interfaces. There are also DevOps integration options available, not least for Slack, PagerDuty, and Jira.

Although built to cater for cloud applications, the Signal Sciences WAF can work with hybrid clouds and server hardware directly. It can also function on premise, in containers, or in the cloud. In terms of security, it blocks all common OWASP attacks, as well as misbehaving bots, and denial of services attacks. The software is fully PCI 6 compliant.

Overall, the Signal Sciences WAF doesn't just focus on security, but also performance, reliability, as well as overall management operability.

Other cloud firewalls to consider

Web Application Firewalls are becoming increasingly common, especially with the move toward remote working. Here we'll begin to list additional WAF vendors worth looking into on top of the original best of listed above.

Perimeter 81 has launched a Firewall-as-a-Service (FaaS) solution, which aims to secure traffic across an organization's hybrid cloud network by providing granular control of traffic in order to prevent breaches. Organizations can limit access to their cloud network based on user or group identity, as well as define traffic to enforce specific security policies, and restrict access to data in a flexible but secure way.

  • Make your home workers secure and productive with a remote access VPN.
  • Check out our review of Firewalla, a different kind of firewall.