Beyond the Tunnel: Why VPNs are Fading Fast — Modernizing Secure Remote Access with SASE, SDP, and ZTNA

VPN — The End?

For decades, Virtual Private Networks (VPNs) have been the trusty steeds of secure remote access, cloaking our digital journeys in encrypted tunnels. But like trusty steeds facing the dawn of automobiles, VPNs are showing their cracks in the age of cloud-centric enterprises, distributed workforces, and ever-evolving cyber threats. Their inherent limitations pose significant risks and are the sworn enemy of agility, demanding a shift towards modern alternatives that deliver robust security, unparalleled flexibility, and seamless user experiences.

To avoid confusion, let me first translate those nasty acronyms I used in the title into something more understandable.

Demystifying the Acronyms: Understanding ZTNA, SDP, and SASE

In the ever-changing world of cybersecurity, acronyms fly and technologies shift. Navigating this landscape can be confusing, especially when the industry seems to be on a mission to break the world record for the most used acronyms, the likes of ZTNA, SDP, and SASE. Don’t worry, I got your back here; read on.

In a nutshell:

  • ZTNA: Least privilege access based on continuous verification, minimizing the attack surface.
  • SDP: Dynamically protect individual applications and resources, precise control.
  • SASE: Converged security services at the network edge, cloud-based and scalable.

Later in the article, I will go into those technological approaches in more detail, so bear with me.

Please also excuse me for being unable to list and write about all the other options. Don’t get upset if I left out your favorite alternative to traditional VPNs; instead, drop me an email or Telegram message and let me know what it is so I can include it in one of my following articles :)

At this point, I want to share something that you may want to explore: ZeroTier, which is a versatile multi-faceted technology that blends SDN, SD-WAN, and Zero Trust principles to create secure, flexible, and cost-effective virtual networks. You could say that it has some components of ZTNA and also SDP. Its unique blend of features makes it well-suited for diverse use cases, particularly in scenarios where traditional VPNs or hardware-based networking solutions face challenges or limitations. And you can use it for free, for your Home Network, or whatever you want to try it out with. I did a video about it in the past:

But let's get back to the topic on hand.

VPNs: A Legacy Tarnished by Vulnerabilities:

While VPNs provided invaluable security in their time, their limitations are becoming increasingly untenable:

  • Security Flaws: Leaky encryption protocols, vulnerabilities in VPN servers, and reliance on trusted networks once breached (think lateral movement exploits) expose sensitive data. Recent headlines like the two Ivanti Zero Day Vulnerabilities, where attackers exploited critical bugs in popular VPN devices, underscore this inherent risk. The trust placed in centralized gateways also creates single points of failure, attractive targets for malicious actors.
  • Performance Bottlenecks: Routing all traffic through a centralized VPN gateway can be a Formula 1 car stuck in rush hour. For geographically dispersed users accessing cloud applications, latency and bandwidth issues abound, impacting the user's productivity and overall efficiency. We all know how it feels to have users call the Helpdesk with that “My Application is soooo slow” story.
  • Limited Visibility: Traditional VPNs operate as black boxes, offering little visibility into user activity and network traffic within the tunnel. This hinders threat detection, forensic analysis, and incident response capabilities, leaving IT teams flying blind in the event of a breach. While there are solutions to counter this, they often are pricey and need to be more affordable for every organization.
  • Management Headaches: Configuring, managing, and scaling VPN infrastructure can be complex and resource-intensive. Maintaining on-premises servers, dealing with software updates, and juggling user access require dedicated personnel and expertise, a drain on valuable IT resources that often are stretched thin already.

Case Closed: Real-World Dangers of Relying on VPNs:

The Ivanti Zero Days incidents weren’t just PR hiccups but stark reminders of the potential consequences of relying on outdated technology. By exploiting vulnerabilities in widely used VPN software, attackers could steal credentials, inject malware, and even pivot to internal networks, causing significant disruption and data exfiltration. [1] Other recent examples, like the VPNFilter malware campaign, which infected thousands of devices and disrupted internet access, further highlight the fragility of VPN-based security. These incidents are not isolated anomalies; they are alarming wake-up calls demanding a shift towards more robust and adaptable security architectures.

Enter the Modern Stage: Secure Access Reinvented:

Fortunately, the security landscape isn’t stuck in the slow lane. Innovative alternatives have emerged, redefining secure remote access. As promised earlier, let's look into a little more detail about the three that I picked for this article:

  • Secure Access Service Edge (SASE): This cloud-based security powerhouse converges multiple services like SWG, CASB, ZTNA, and FWaaS at the network edge, delivering layered security wherever users access resources. With its distributed PoPs strategically placed around the globe, SASE ensures optimal performance and scales effortlessly to accommodate growth. Think of it as a decentralized security command center guarding every access point to your digital landscape. Read here for more:
  • Software Defined Perimeter (SDP): Taking a dynamic approach, SDP protects applications and resources directly, granting access only to authorized users and devices from any location. Imagine individual applications wrapped in protective bubbles, eliminating the need for a vast blanket tunnel around your entire network. This minimizes the attack surface and enhances both security and scalability.
  • Zero Trust Network Access (ZTNA): Embracing the principle of least privilege, ZTNA grants access based on user context and device posture, continuously verifying trust before allowing entry. Picture a meticulous gatekeeper who inspects every credential and device posture before granting even the most limited access to specific resources. This minimizes the attack surface, removes implicit trust within networks, and prevents lateral movement in the event of a breach. Refer to what NIST has to say about this approach:

The Advantages of Beyond the Tunnel:

These modern approaches offer compelling benefits over their VPN predecessors:

  • Enhanced Security: Identity-based access control, layered security services, and continuous authorization significantly reduce the attack surface and provide multi-layered defense against advanced threats.
  • Improved User Experience: Seamless and transparent access to applications from any device and location boosts user productivity and eliminates location-based connectivity issues.
  • Greater Scalability: Cloud-based architecture and dynamic resource allocation effortlessly accommodate changing needs and organizational growth, eliminating costly infrastructure upgrades.
  • Simplified Management: Centralized management and automated security policies reduce operational overhead and complexity, freeing IT teams to focus on strategic initiatives.

Choosing the Right Path: Matching Needs to Solutions:

The best alternative isn’t a one-size-fits-all solution; it depends on your specific requirements:

  • SASE’s comprehensive security and scalability make it the ideal choice for organizations with complex multi-cloud environments and geographically dispersed workforces. Its ability to integrate seamlessly with cloud applications and offer granular access control across diverse ecosystems makes it a powerhouse for securing remote access in an increasingly cloud-centric world. Think of it as a Swiss Army knife for your cloud security needs, adaptable and readily deployable across various battlegrounds.
  • If you prioritize granular application access control and protecting specific resources, SDP’s dynamic perimeter approach offers a focused and secure solution. By directly wrapping individual applications or services in layers of protection, SDP eliminates the need for blanket network tunnels, minimizing the attack surface and providing precise control over user access. Consider it a high-tech moat surrounding your most critical assets, keeping unwanted visitors at bay.
  • ZTNA shines when minimizing the attack surface and implementing least-privilege access are top priorities, especially for organizations handling susceptible data or operating in highly regulated industries. ZTNA significantly reduces the risk of unauthorized access and lateral movement within the network by continuously verifying user and device trust before granting access. Envision it as a meticulous bouncer at an exclusive club, scrutinizing every detail before allowing even a peek inside.

Hybrid Deployments and Continuous Evolution:

Choosing the right approach to secure remote access isn’t about replacing one technology with another. That has never really worked well without considering all the factors. Instead, it’s about understanding the strengths and weaknesses of each solution and crafting a multi-layered security strategy that leverages them effectively. Many organizations opt for hybrid deployments, combining SASE, SDP, and ZTNA elements to meet their specific needs. For instance, you can use SASE for overall cloud security and user access control while implementing SDP for sensitive applications and ZTNA for internal resource access. It’s like building a custom security fortress, utilizing each brick for its unique defensive properties. How is that for a best-of-breed approach?

Remember, the security landscape is constantly evolving, and so should your approach to secure remote access. Regularly assess your security posture, stay informed about emerging threats and trends, and be prepared to adapt your security architecture as needed. Think of it as an ongoing security sprint, constantly refining your defenses to stay ahead of the ever-changing threat landscape.

By embracing modern alternatives like SASE, SDP, and ZTNA and building a comprehensive security strategy, organizations can move beyond the limitations of VPNs and create a secure, scalable, and user-friendly environment for remote access. This transition is not just an option; it’s a necessity in today’s digital landscape.

Transport Layer Encryption: An Extra Shield for Your Data’s Journey

Before I end, let me take up this topic as well, as it is equally important in protecting your data.

Remember the OSI Model? The Transport Layer is also known as Layer 4

While ZTNA, SDP, and SASE provide robust security frameworks for remote access and data protection, they’re not standalone solutions. Layer 4 encryption is a complementary layer, bolstering security by safeguarding data as it traverses networks.

Why Layer 4 Encryption Matters:

  • Confidentiality: Encrypting data at Layer 4 (the transport layer) ensures that it remains unreadable to unauthorized parties even if intercepted. Think of it as sealing sensitive information in a tamper-proof vault, accessible only to those with the correct keys.
  • Integrity: Layer 4 encryption protects data integrity, ensuring it arrives unaltered and preventing malicious modification. It’s like applying an invisible seal to a package, ensuring no one tampers with its contents en route.
  • Compliance: Many industries, such as healthcare and finance, have stringent data privacy regulations that mandate encryption in transit. Layer 4 encryption helps organizations meet compliance requirements and protect sensitive information.
  • Defense-in-Depth: By encrypting data at the transport layer, you add an extra layer of protection within a multi-layered security strategy. It’s like adding a reinforced lock to a vault that already has multiple security measures in place.

How It Works:

Layer 4 encryption typically utilizes protocols like IPsec (Internet Protocol Security), TLS (Transport Layer Security), or DTLS (Datagram Transport Layer Security — UDP-based counterpart to TLS) to encrypt data packets before transmission. These protocols create secure tunnels through which data flows, shielding its contents from prying eyes.

Benefits of Layer 4 Encryption:

Though the benefits seem pretty obvious, let me list a few here; there certainly are many more.

  • Protection against eavesdropping and interception: Encrypted data is useless to unauthorized parties, even if they manage to capture it.
  • Safeguards against man-in-the-middle attacks: Encrypting data end-to-end prevents attackers from intercepting and modifying it in transit.
  • Enhances data privacy and compliance: Encryption demonstrates a commitment to protecting sensitive information and meeting regulatory requirements.
  • Provides additional layer of security: Complements other security measures like ZTNA, SDP, and SASE, creating a more resilient defense against threats.

I hope you learned something today, and feel free to contact me with questions or suggestions for future articles.



Sigmund Brandstaetter CISSP, CCSP, CISM, OSCP, CEH

With a total of 30 years in the IT Industry, I have focused on Cybersecurity (Services) and related skills over the past 15 years,