Secure web gateway: Everything you need to know

What is a secure web gateway?

A secure web gateway (SWG) is a security solution that monitors, filters, and controls web traffic to protect users from online threats. It blocks access to dangerous websites, filters content, and scans for malware in real time, keeping users safe without slowing them down.

Unlike traditional security tools that focus on network-level threats, an SWG specifically safeguards web activity. It filters URLs, scans files, and applies security rules in real time to ensure safe internet access.

Why organizations need a secure web gateway

The traditional network perimeter is gone. Employees work from anywhere, accessing cloud apps instead of on-premise servers. This shift opens the door to security risks — phishing attacks, ransomware, and data breaches — that can compromise sensitive data and disrupt business operations.

An SWG can help prevent many of these problems. Enterprises rely on them to:

• Protect employees and users by blocking access to malicious websites and applications.
• Prevent malware infections from downloads and compromised web pages.
• Inspect encrypted traffic (SSL/TLS) to uncover hidden security threats.
• Meet regulatory compliance requirements, especially in sectors that handle sensitive data.
• Stop data leaks by monitoring and restricting outbound information sharing.

Key features and capabilities of an SWG

A secure web gateway (SWG) does more than block malicious websites. Let’s take a closer look at the key security capabilities that make SWGs essential for businesses.

URL filtering and content control

URL filtering is a type of web filtering that helps organizations control which websites and web applications employees can access, blocking harmful or non-work-related content. It prevents users from landing on malicious sites, limits distractions, and enforces bandwidth restrictions on streaming services.

Traffic can be filtered based on URL categories, user roles, groups, or specific devices. Administrators also get information on which sites employees visit and when — this feature helps them monitor and refine access policies as needed.

Malware and cyber threat protection

Cybercriminals use websites, pop-ups, and downloads to spread malware. An SWG provides advanced threat protection by using real-time virus signatures and known malware lists. Its key security capabilities include:

• Behavioral analysis to detect zero-day threats.
• Sandboxing to analyze suspicious files in an isolated environment.
• AI-driven threat intelligence to identify new attack patterns.

Solutions like NordVPN's Threat Protection Pro™ add an extra layer of defense. This tool blocks malware, intrusive ads, and phishing attempts while scanning downloads for security threats.

TLS inspection

With over 80% of web traffic encrypted with SSL/TLS, attackers use HTTPS to disguise malware, phishing pages, and data theft. TLS inspection allows a Secure Web Gateway (SWG) to decrypt, analyze, and re-encrypt traffic before sending it to the user. Acting as a man-in-the-middle proxy, the SWG uses its own trusted certificate to inspect encrypted content safely.

By performing TLS inspection, an SWG can detect and block phishing attacks hidden in encrypted pages, prevent malware downloads from seemingly secure websites, and stop data exfiltration through encrypted channels.

Data loss prevention

Data loss prevention stops sensitive data from leaving an organization’s network — whether by accident or intent. It achieves that by monitoring data movement, enforcing security policies, and adhering to industry compliance regulations like the GDPR, HIPAA, and PCI-DSS.

How does a secure web gateway work?

SWGs act as security checkpoints for internet traffic, protecting users from online threats while enforcing acceptable use policies. They control access to sensitive content, prevent malware infections, and stop data leaks before they can cause harm. But how do they actually work? 

Traffic flow and inspection

An SWG inspects all web traffic before allowing it through. It applies policies, scans for threats, and logs activity for security monitoring. Here's what happens when a user tries to access a website or download content:

1. 1.The SWG checks the requested URL against a categorized database. If it's safe and allowed under company policy, the SWG grants the user access. If not, it doesn’t.
2. 2.The SWG regulates access to web-based applications, allowing or restricting specific functions (e.g., uploads, file sharing) based on policy.
3. 3.Any downloads or scripts are scanned against known malware signatures. If a threat is detected, the download is blocked before it can execute.
4. 4.The SWG decrypts encrypted traffic, scans for hidden threats, and re-encrypts it for secure delivery.
5. 5.It analyzes content for sensitive information (e.g., credit card numbers and confidential business data) and blocks unauthorized transfers.
6. 6.User activity, security incidents, and policy violations are recorded for reporting, forensics, and compliance audits.

Real-time monitoring and policy enforcement

Secure web gateways enforce company policies as users browse. Every request is checked against company rules to authenticate users, ensure compliance, and block risky behavior before it becomes problematic. This enforcement includes:

• Compliance policies: Ensuring regulatory requirements (e.g., GDPR, HIPAA) are met.
• User activity monitoring: Tracking internet usage to detect risky behavior.
• Application control: Restricting access to unauthorized apps.
• Bandwidth management: Preventing excessive use of network resources.

Integrations with other security solutions

A next-gen secure web gateway integrates with other security services to provide advanced protection.

Next-generation firewalls (NGFW)

While firewalls protect the network perimeter, an SWG focuses on web-based threats. Together, they block malicious content, prevent unauthorized access, and inspect encrypted data for hidden dangers.

Cloud access security broker (CASB)

A CASB provides cloud security for applications like Google Workspace, Microsoft 365, and Slack. Together, SWG and CASB  ensure safe access to both general web traffic and cloud services without gaps in coverage.

Zero-trust network access (ZTNA)

ZTNA follows a "never trust, always verify" approach to access control. When combined with SWG, the zero-trust security approach secures connections for remote workers, protects against ransomware, and simplifies cloud migration security.

Although ZTNA may seem similar to a remote VPN, they work differently. Learn more about ZTNA vs. VPNs.

Secure web gateway vs. other security solutions

Not all security tools do the same job. Firewalls, proxies, and CASBs each serve different purposes, and understanding how they compare to secure web gateways helps build a strong, layered defense.

Secure web gateway vs. firewall

An SWG and a firewall both play a role in cybersecurity, but they serve different purposes. While firewalls protect networks by controlling inbound and outbound traffic at the perimeter, SWGs focus on securing internet access by filtering URLs, blocking malware, and enforcing security policies.

Secure web gateway vs. proxy 

A proxy server and an SWG both sit between users and the internet, but they serve different purposes.

• Proxies act as intermediaries, routing traffic and increasing privacy. They cache content to speed up web access but don't inspect traffic for threats.
• SWGs offer real-time security, scanning web traffic, filtering URLs, and blocking malware before it reaches users.

If private internet access is the priority, a proxy may be enough. If security and compliance are the goal, an SWG is the better choice.

Secure web gateway vs. cloud access security broker 

A CASB and an SWG both manage internet traffic but focus on different areas.

• SWGs secure all web traffic, blocking threats and enforcing policies.
• CASBs focus on cloud apps like Google Workspace and Microsoft 365, ensuring safe usage and compliance.

If an organization wants to secure general web traffic, an SWG is the solution. If the priority is securing SaaS apps, a CASB is the better fit. Many businesses use both together to cover all web security needs.

Next-gen secure web gateway

As cybercriminals evolve their attack strategies, traditional SWGs that rely on hashes, static signatures, and outdated web crawling are losing effectiveness. Next-gen SWGs use real-time intelligence, AI-driven detection, and cloud-native security to keep up with the digital transformation and stay ahead of modern attacks.

Integration with SASE

Secure access service edge (SASE) merges networking and security services into a single platform. By combining SWG, DNS security, zero-trust network access (ZTNA), and data loss prevention (DLP), SASE provides a more efficient and scalable way to secure internet traffic.

Cloud SWG

Organizations used to secure internet access by deploying web gateways within on-premise data centers, which added complexity and couldn't easily scale. Today, cloud-delivered SWGs — often part of a security service edge (SSE) platform — offer a more flexible, integrated approach to web security.

A cloud SWG combines URL filtering, TLS decryption, SaaS application control, and advanced threat prevention with firewall capabilities. This step creates a reliable security layer that works across any location.