VPN vs. SDP vs. ZTNA: Which is the Best Security Solution for the Remote Work Era?

The workplace has transformed dramatically over the past few years. The COVID-19 pandemic accelerated existing remote work trends, with 55% of companies now having significant remote employees.

Additionally, enterprise adoption of cloud infrastructure has skyrocketed. 82% of enterprise workloads will be in the cloud by 2025 versus just 33% in 2018.

As a network security professional, I‘ve seen firsthand how this paradigm shift has exposed the glaring weaknesses in traditional Virtual Private Networks (VPNs).

VPNs served enterprises well in the past. But in today‘s cloud and mobile-first world, expectations around user experience, availability, and security have changed dramatically.

In this extensive guide, I‘ll explain how modern solutions like Software Defined Perimeters (SDP) and Zero Trust Network Access (ZTNA) can overcome VPN limitations and securely enable remote access in the cloud era.

I‘ll cover:

• The growing security risks of VPNs
• How SDP and ZTNA are better equipped for the cloud
• Head-to-head comparison between the technologies
• Transitioning strategy from VPNs to SDP/ZTNA

Let‘s get started!

VPNs Pose Serious Security Gaps in the Remote Work Era

VPNs have been the go-to technology for remote user access for more than 20 years. But the capabilities that once made them attractive have now become serious security risks:

Antiquated Access Control Models

VPNs operate on an implicit trust model – once a user authenticates, they get full access to the internal network and all applications.

This made sense when applications were centralized in data centers and users were corporate managed.

But now, your workforce is distributed and accessing dozens of SaaS apps in the cloud. Broad network access poses a massive security risk.

Studies show 95% of breaches involve stolen credentials. And VPNs have no way to continuously validate user identities and restrict access after login.

Once the VPN tunnel is established, it‘s open season for lateral movement and privilege escalation. This makes your network a sitting duck despite access controls at the application layer.

Device Security Blindspot

61% of security professionals say compromised user devices are their top concern.

But VPNs have zero visibility into the security state of BYOD and unmanaged endpoints. Their design blindly trusts devices once users are authenticated.

This allows infected, vulnerable and non-compliant devices to freely access your network and applications after connecting via VPN.

Technology Debt and Risky Dependencies

Most enterprise VPNs rely on on-premise concentrators from legacy vendors. These physical appliances present huge technology debt:

• Capacity planning challenges as the workforce scales up.
• Availability risks from hardware failures.
• Costly licensing tied to bandwidth or connected endpoints.
• Complex multi-cloud support requires complex networking.

Additionally, VPN servers themselves have been rife with critical vulnerabilities like:

• CVE-2019-11510 – Pulse Secure VPN critical arbitrary file disclosure bug.
• CVE-2018-13379 – FortiGate VPN SSL VPN critical vulnerability enabling unauthenticated access.

These factors combine to make VPN a precarious choice for secure remote access today.

How SDP and ZTNA Overcome VPN Limitations

Unlike VPNs, SDP and ZTNA are built from the ground up to securely enable access in the cloud and remote work era.

Some key advantages over VPN:

User and device access controls

SDP/ZTNA verify user identities via strong multi-factor authentication before creating device trust certificates. Access is only granted after validating both user identity and device security posture.

This overcomes the blind trust problem with VPNs that leave networks exposed after initial login.

Least privilege access

Instead of the broad network access VPNs provide, SDP and ZTNA grant access to only specific resources based on dynamic policy.

There are no open ports or broad tunnels. Just secure microsegments to only the applications and resources authorized for that user.

This minimizes internal blast radius and shuts down lateral movement.

Browser based access

Users can remotely access internal apps and resources right from their browser without any client software.

This removes device dependencies, improves performance, and enhances availability.

Cloud platform based

SDP and ZTNA solutions are delivered via cloud platforms, removing the technology debt and bottlenecks of VPN appliances.

Cloud delivery also enables easy scaling, quick deployment, and affordable subscription models.

Let‘s now look at how SDP and ZTNA compare to VPNs across various metrics.

SDP vs VPN – A Detailed Head-to-Head Comparison

Metric	SDP	VPN
Access Control	Least privilege, context-aware, dynamic policies	Full network access after authentication
Authentication	Continuous validation of user + device identity	Only initial user authentication
Encryption	Application-level, encrypted secure microsegments	Network level encryption via tunnel
Monitoring	Detailed session logs and analytics	Limited auditing and reporting capabilities
Infrastructure	Hardware and location agnostic, elastic scale	On-premise concentrators, constrained scale
Multi-Cloud Support	Consistent access across hybrid/multi-cloud	Complex networking, availability risks
Vulnerability Surface	No exposed ports or services	VPN servers frequently exploited
Performance	Zero trust architecture minimizes latency	Bottlenecks at VPN concentrators

Multiple research studies validate the security advantages of SDP over legacy VPNs:

• Gartner: SDP addresses 80% of VPN risks
• Enterprise Management Associates: SDP reduces threat exposure by 98% over VPNs

SDP is purpose built for the cloud and mobile era, overcoming the inherent design flaws of VPNs.

ZTNA vs VPN – The Key Differentiators

Metric	ZTNA	VPN
Architecture	Zero trust, least privilege access	Perimeter based defenses, broad network access
Encryption	End-to-end encrypted microsegments	Encrypted tunnel but internal traffic exposed
User Experience	Fast, browser based access	Client software, performance lags
Authentication	Continuous validation of user identity and device health	Initial user authentication only
Deployment	Cloud delivered, agentless access	Appliance based, complex remote client
Flexibility	Application based access policies	Network perimeter restrictions

According to Forrester, the three main benefits enterprises realize with ZTNA are:

1. 66% reduction in breach risk by removing access to unneeded resources
2. 80% decrease in networking costs by eliminating MPLS and VPNs
3. 63% improvement in user experience via browser based access

Zero trust principles fundamentally improve security and user experience compared to VPNs.

Complement VPN with SDP/ZTNA for Enhanced Security

Migrating completely away from legacy VPNs may not be practical or necessary for some organizations in the short term.

In these scenarios, SDP and ZTNA can meaningfully complement existing VPN infrastructure:

• Use VPN for general internet access from remote locations
• Enable SDP/ZTNA for access to sensitive applications like finance systems, HR databases etc. This protects critical systems with zero trust security while VPN continues to provide basic connectivity.
• For third parties and non-employees, cut off VPN access and only allow access to required resources via SDP/ZTNA. This significantly reduces security risks from external users.

A staggered transition like this allows organizations to gain experience with SDP/ZTNA and start realizing benefits without overhauling their entire network security posture.

Over 12-24 months, VPN usage can be phased out completely in favor of the modern ZTNA architecture.

Key Takeaways on the VPN vs SDP vs ZTNA Debate

Here are my main recommendations based on the extensive analysis above:

• VPNs are high risk due to inherent flaws like assumed trust, open ports, and unrestricted access. These make them dangerous for the cloud and remote work era.

• SDP and ZTNA overcome these issues through zero trust principles like least privilege access, user/device verification, and network cloaking.

• Complement VPNs with SDP or ZTNA to enhance security for high risk scenarios involving external users and sensitive applications. This enables a gradual transition.

• Evaluate SDP and ZTNA vendors for capabilities like identity management integration, microsegmentation, and flexible deployment models to find the right long term solution.

The remote work genie is out of the bottle. As your workforce grows more distributed, only a zero trust architecture like SDP or ZTNA can provide secure yet seamless application access. VPNs may still serve basic connectivity needs on a transitional basis.

But for enterprise security, it‘s clear that the future is SDP and ZTNA. I hope this guide has helped you understand the relative merits and how to choose the right solution for your organization.