What Is a Virtual Firewall?
A virtual firewall is a virtualized instance of a next-generation firewall, used in cloud and virtualized environments to secure east-west and north-south traffic.
Virtual firewalls are a type of software firewall which inspect and control north-south perimeter network traffic in public cloud environments, and segment east-west traffic inside physical data centers and branches. Virtual firewalls offer advanced threat prevention measures via microsegmentation.
How Virtual Firewalls Work
Also known as cloud firewalls or virtualized NGFWs, virtual firewalls grant or reject network access to traffic flows between untrusted zones and trusted zones. Virtual firewalls provide consistent threat prevention and inline network security across cloud based environments. This helps network security teams regain visibility and control over traffic in their cloud networks. Since virtual network firewalls are deployed in a virtual form factor, they are highly scalable, making them ideal for protecting virtual environments.
Ideally, a virtual firewall will inspect incoming and outgoing traffic at the application layer and detect attacks that cannot be detected by cloud service providers (CSP) Layer 4 firewalls. Virtual firewalls operate such that they can look within applications and decide whether to allow requests based on the content, not just the port number. This feature allows organizations to prevent distributed denial-of-service (DDoS) attacks, HTTP floods, SQL injections, cross-site scripting, parameter tampering, and Slowloris attacks.
What Is a Firewall?
Virtual Firewall Features
Virtual firewall features can vary depending on the solution and vendor. Advanced virtual firewalls are often equipped with more sophisticated features better suited to address modern network security challenges. These capabilities are important for maintaining a robust defense strategy for enterprise level web infrastructures and combating the dynamic nature of online risks.
Layer 7 Firewall Capabilities
Layer 7 capabilities allow the inspection of traffic at the application layer, enabling the detection of sophisticated attacks that traditional Layer 4 firewalls cannot catch. It can identify and stop various attacks such as DDoS, HTTP floods, SQL injections, cross-site scripting, parameter tampering, and more by analyzing the content of the traffic rather than just the port number.
Threat Prevention
Threat prevention includes intrusion prevention system (IPS) capabilities, inspecting all traffic for known threats regardless of port, protocol, or encryption, and automatically blocking vulnerabilities, spyware, malware, command and control activities, and port scans.
URL Filtering
URL Filtering goes beyond basic domain name filtering, offering more granular control over web access. It allows organizations to block or allow access to specific parts of a website, reducing the risk of breaches and aiding productivity without compromising security.
Malware Prevention
Malware prevention usually involves multiple methods of analysis to detect and prevent unknown file-based threats, including machine learning and dynamic analysis. It also often includes real-time signature streaming to protect against newly discovered threats.
DNS Security
This feature uses predictive analytics and machine learning to block attacks utilizing DNS. It offers integrated protections and comprehensive analytics for deeper insights into threats.
IoT Security
Added IoT security features are specifically designed for IoT environments, providing visibility into unmanaged devices, detecting behavioral anomalies, and offering risk-based policy recommendations. These features typically don't require additional sensors or infrastructure.
Mobile Traffic Inspection
This capability ensures the security of mobile device traffic, both incoming and outgoing, by leveraging the capabilities of the virtual firewall to inspect all mobile traffic.
Consolidated Security Management
Centralized management systems allow for the unified administration of virtual firewalls across multiple cloud deployments. This feature includes rich logging and reporting capabilities for better visibility into network traffic and threats.
Application Identification and Control
This technology identifies applications traversing the firewall regardless of port, protocol, and encryption, providing visibility and control over applications, even those that attempt to evade detection.
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Benefits of Virtual Firewalls
Virtual firewalls offer the features that security teams need to secure multi-cloud environments, including full visibility and control, consistent policy enforcement, application security, exfiltration prevention, compliance and risk management, security automation, and cloud-agnostic management.
Full visibility and control
Virtual firewalls help security teams understand which applications are traversing cloud deployments, where they are coming from and going to, and the user’s identity. Rich centralized logging and reporting capabilities provide visibility into virtualized and containerized applications, users, and content.
High-end virtual firewalls integrate deeply into public cloud based environments to provide additional context like tags and other metadata. A tag-based policy model, tight integration across all major CSPs, and a fully documented XML API allow network security teams to create flexible policies that can adapt to dynamic environments regardless of the underlying infrastructure.
Consistent policy enforcement
Many organizations have critical applications hosted in on-premises data centers, private clouds, and multiple public clouds. To enforce consistent security policies across all three parts of this hybrid environment, the security team must duplicate policies across three clouds using the native controls in each — a labor-intensive and error-prone task. Managing the overall security posture requires the team to develop expertise in each cloud’s controls and management interface.
Typically, virtual firewalls deployed in multiple public and private cloud environments can all be managed from the same console. This enables security teams to deliver the same best-in-class security services and solutions to each environment and extend a uniform policy model across the entire ecosystem. Ultimately, this ensures the consistency and simplification of an organization’s overall security posture.
Compliance and risk management
Risk management and compliance activities benefit from virtual firewall features such as application allow listing, which reduces the attack surface by allowing specific applications and denying all else. Allow list policies also allow organizations to segment applications communicating with each other across different subnets and between virtual private clouds (VPCs) for regulatory compliance.
Security automation
Quality virtual firewalls include management and automation features that enable developers to embed security in DevOps workflows and other application development processes. Consequently, virtual firewalls can support cloud native, agile, and waterfall development methodologies. Developers can automatically provision virtual firewalls with a working configuration, complete with licenses and subscriptions. Auto-scale templates, bootstrapping, and other automated configuration capabilities ensure that virtual firewalls can be easily deployed to scale with increased demand.
Virtual firewalls commonly integrate with automation and orchestration platforms such as Jenkins®, Terraform®, Ansible®, and SaltStack® so developers can deploy firewalls as a routine task in application development to ensure security at DevOps speed.
Cloud-agnostic management
Virtual firewalls usually support all major CSPs, including AWS®, Azure®, GCP®, Oracle Cloud®, and Alibaba Cloud.
Virtual firewalls can be managed via network security management systems. This eliminates the need for multiple security solutions by providing comprehensive visibility and control across multi-cloud and hybrid cloud environments from a single console.
Public Cloud Security Challenges that Create the Need for Virtual Firewalls
The journey to the cloud is not optional. Enterprises that hesitate or fail to execute are likely to be left behind as their competitors take advantage of the opportunities. Cloud delivers tangible business benefits, such as consumption-based IT spending, speed, agility, and improved user experience — all essential to survive and thrive in today’s dynamic marketplace.
Multi-Cloud Complexity
With 81% of public cloud users working with multiple providers, security architects face the challenge of developing comprehensive cybersecurity strategies across diverse cloud based platforms. This complexity can lead to security gaps and increased operational demands.
Divided Security Responsibility
Cloud Service Providers (CSPs) like AWS, Azure, GCP, Oracle Cloud, and Alibaba Cloud offer basic native security for their infrastructures. However, securing applications, data, and other elements in the cloud is the user's responsibility. This division can lead to misunderstandings and vulnerabilities if not properly managed.
Shared Security in XaaS (Everything as a Service)
The shared responsibility model means CSPs secure the cloud platform (hardware, operating system, network), while customers must secure their applications and data. This model also extends internally within organizations, with different teams (security, developers, DevOps) having distinct roles in maintaining cloud security.
Platform Security Measures
CSPs provide a range of native security measures, including secure network architecture, access control, transmission protection, and account security (like MFA and SSL). These are foundational but often not sufficient for comprehensive security.
Service-Specific Security
For IaaS services, additional security features are provided by CSPs, such as instance isolation, MFA-protected access, and firewalls. However, the customer is still responsible for configuring and managing these security features effectively.
Application Layer Security
The customer is fully responsible for securing the application layer, which is prone to the largest number of threats. This requires comprehensive network security services and solutions that complements CSP security, offering features like threat prevention, malware detection, URL filtering, and data exfiltration prevention.
Virtual Firewall vs. Physical Firewall
The most important difference between a hardware and virtual firewall is the physical appliance, but there are several others worth noting.
Both virtual and traditional firewalls play critical roles in network security. Virtual firewalls are not better than hardware firewalls or vice versa. Each is appropriate for different scenarios.
| Differences Between Virtual Firewalls and Hardware Firewalls | ||
|---|---|---|
| Parameters | Virtual firewall | Hardware firewall |
| Form factors | Software -Installed on server or virtual machine -Operates on a security operating system typically run on generic hardware with a virtualization layer on top |
Physical, individual appliance Installed between network elements and connected devices |
| Complexity | Quick, easy deployment using cloud automation tools Usable for non-network security experts |
Requires physical activities, like rearranging cables and establishing configuration parameters using a command line interface Skilled staff are required for installation and management |
| Costs and ROI | Less costly to deploy and maintain Virtual firewalls can provide a significant ROI. |
Usually require higher initial investment in hardware and ongoing expense of staff ROI equates to savings by preventing attacks, which is difficult to calculate |
Types of Firewalls Defined and Explained
Questions to Ask When Purchasing a Virtual Firewall
Organizations investigating virtual firewall options may wish to consider:
Does the virtual firewall provide full-scope threat prevention?
Virtualized environments need real threat prevention which includes filtering and monitoring. Essential capabilities to look for include intrusion prevention, URL filtering, SSL decryption, DNS security, file blocking, network anti-malware and denial-of-service protection.
Does the virtual firewall reduce attack surfaces?
Virtual firewalls often provide lateral movement protection – for traffic that flows inside the private cloud – which can reduce the attack surface in virtualized environments.
Does the virtual firewall offer application-centric security policies?
The ability of virtualized environments to deliver applications on demand means firewalls should have application-centric security policies capabilities, such as the ability to identify any application, regardless of its classification, behavior or location.
Is the virtual firewall capable of automated provisioning and scaling?
In some instances, virtual firewalls can be provisioned automatically to keep pace with continuous integration and continuous delivery (CI/CD) expectations, and even be provisioned directly into DevOps workflows.
Does the virtual firewall allow visibility across environments?
The ability to manage deployments in multiple virtualized environments can reduce time, effort, error and expenses.
