What Is VPN and How Does It Work?

A VPN, or virtual private network, is a technology that creates a protected connection over an existing network, usually the internet. It helps secure data in transit by using tunneling, encryption, authentication, and access controls between a user device and a VPN endpoint. Businesses commonly use VPNs to support secure remote access, connect offices, and protect traffic moving between users, networks, and internal systems. NIST defines a VPN as a virtual network built on top of existing physical networks that can provide a secure communication mechanism for data transmitted between networks or nodes.

What Is a VPN?

A VPN is a secure connection that allows a device or network to communicate through a protected tunnel.

Instead of sending traffic directly across the public internet without added protection, a VPN wraps traffic inside a secure connection between two points. These points may be:

• A remote employee’s laptop and a company VPN gateway
• A branch office and headquarters
• A business network and a cloud environment
• An administrator’s device and internal systems

VPNs are commonly used when users need access to private resources from outside the office.

How Does a VPN Work?

A VPN works by establishing a secure tunnel between a user device and a VPN server, firewall, or gateway.

The basic process usually looks like this:

1. The user opens a VPN client or connects through a configured device.
2. The VPN system verifies the user, device, or network.
3. The VPN creates a secure tunnel.
4. Traffic is encrypted before passing through the tunnel.
5. The VPN endpoint decrypts and forwards traffic to the intended resource.
6. Responses return through the protected tunnel.

This helps protect data from easy interception while it moves across untrusted networks.

What Does a VPN Protect?

A VPN mainly protects data in transit.

This means it helps secure traffic while it is moving between a device and a VPN endpoint. A VPN can help protect:

• Remote access sessions
• Business application traffic
• Internal file access
• Administrative connections
• Communications over public or untrusted networks

However, a VPN does not automatically secure the entire device or account. It does not replace:

• Endpoint protection
• Patch management
• Multi-factor authentication
• Identity controls
• Least privilege access
• Security monitoring

This is important because VPN access is only as secure as the users, devices, and configurations behind it.

VPN Tunneling and Encryption Explained

VPNs use tunneling to carry traffic through a protected path.

Tunneling means traffic is encapsulated so it can move through another network while keeping the original communication protected. Encryption helps prevent unauthorized parties from reading the contents of that traffic.

A secure VPN may also use:

• Authentication to verify users or systems
• Integrity checks to detect tampering
• Encryption to protect confidentiality
• Security policies to control allowed traffic

IPsec is one common VPN technology. NIST explains that IPsec provides network-layer security services and can be used with IKE for secure VPN deployment.

Common Types of VPNs

Remote Access VPN

A remote access VPN connects an individual user or device to a private network.

This is commonly used by:

• Remote employees
• IT administrators
• Traveling staff
• Contractors
• Support teams

NSA and CISA note that remote access VPN servers allow off-site users to tunnel into protected networks, which makes them important systems to secure properly.

Site-to-Site VPN

A site-to-site VPN connects one network to another.

This is commonly used for:

• Branch offices
• Headquarters
• Data centers
• Cloud networks
• Partner networks

Instead of each user manually connecting, network gateways maintain the VPN connection between locations.

Client-Based VPN

A client-based VPN requires VPN software installed on the user’s device.

The user signs in, connects to the VPN, and gains access based on assigned permissions.

Clientless VPN

A clientless VPN may provide browser-based access to specific applications or resources without requiring a full VPN client.

Business VPN vs Consumer VPN

Business VPNs and consumer VPNs use similar concepts, but they are usually used for different goals.

A business VPN is mainly used to provide secure access to company systems.

A consumer VPN is usually used to route personal internet traffic through a VPN provider’s server.

Business VPN priorities include:

• Secure remote access
• Internal application access
• Identity verification
• Access control
• Logging
• Policy enforcement
• Administrative oversight

Consumer VPN priorities often include:

• Public Wi-Fi protection
• IP address masking
• Personal browsing privacy
• Regional access

For IT teams, the main concern is not hiding location. The main concern is controlling secure access to business resources.

Why Do Organizations Use VPNs?

Organizations use VPNs because users, offices, and systems often need secure access from outside the main network.

Common VPN use cases include:

• Remote work
• Secure access to internal applications
• Connecting branch offices
• Protecting traffic on public Wi-Fi
• Supporting remote IT administration
• Connecting cloud and on-premises environments
• Providing controlled access for vendors or contractors

VPNs remain widely used because many organizations still rely on private applications, internal networks, and secure administrative access.

VPN Security Risks and Limitations

A VPN improves secure connectivity, but it can also become a risk if poorly configured or outdated.

Common VPN risks include:

• Weak passwords
• Missing multi-factor authentication
• Unpatched VPN servers
• Overly broad access
• Poor logging
• Compromised user devices
• Misconfigured access policies

NSA and CISA recommend hardening remote access VPNs by using strong authentication such as MFA, promptly applying patches and updates, choosing standards-based VPNs, and reducing attack surface by disabling non-VPN features.

A VPN should not mean automatic trust. Users should only receive the access they need, and VPN activity should be monitored.

VPN Best Practices for IT Teams

IT teams can improve VPN security and reliability by following practical controls.

Use multi-factor authentication for VPN access.

Keep VPN gateways, servers, and clients updated.

Limit user access based on role and business need.

Monitor VPN logs for unusual login patterns.

Remove inactive users and unused access.

Use standards-based VPN technologies.

Document VPN access policies.

Review VPN configuration regularly.

Secure the endpoints that connect to the VPN.

These practices help reduce risk while keeping remote access usable for employees and administrators.

How Level Relates to VPN Management

Level helps IT teams and MSPs manage endpoints, automate routine work, and improve operational visibility.

VPNs help secure the connection path, but IT teams still need to manage the devices connecting through that path. A secure VPN strategy works better when teams also have visibility into endpoint health, configuration, access readiness, and remote support needs.

Level can support the broader operational side of remote access by helping teams:

• View and manage endpoints
• Run scripts and automations
• Support remote troubleshooting
• Maintain endpoint visibility
• Reduce repetitive IT tasks

For organizations using VPNs, endpoint visibility matters because remote access depends on both the network connection and the condition of the device using it.

FAQ

What is a VPN?

A VPN, or virtual private network, is a protected connection built over an existing network. It helps secure communication between devices, users, and private resources.

How does a VPN work?

A VPN works by authenticating a user or device, creating a secure tunnel, encrypting traffic, and routing that traffic through a VPN endpoint before it reaches the destination.

What is a VPN used for?

A VPN is used for secure remote access, branch office connectivity, internal application access, administrative access, and protecting data in transit over untrusted networks.

Does a VPN make you completely secure?

No. A VPN protects the connection path, but it does not replace endpoint security, patching, MFA, identity controls, least privilege access, or monitoring.

What is the difference between a remote access VPN and a site-to-site VPN?

A remote access VPN connects an individual user or device to a private network. A site-to-site VPN connects two networks together, such as a branch office and headquarters.

Should businesses still use VPNs?

Yes, many businesses still use VPNs for secure remote access and network connectivity. They should be hardened, updated, monitored, and combined with strong identity and endpoint controls.

Summary

A VPN creates a protected connection over an existing network. It helps secure data in transit, supports remote access, and allows users or networks to connect to private resources. VPNs are useful for business connectivity, but they must be configured carefully, kept updated, protected with strong authentication, and supported by endpoint visibility and access controls.