Users at a client’s remote office were constantly experiencing issues accessing corporate applications via VPN; connection drops and slowness complaints had become a daily routine. This situation once again demonstrated that a VPN not only provides a security tunnel but can also incur significant costs in terms of management, performance, and architecture. We often view VPNs as a “security shield,” but the complexity and indirect costs they introduce can actually outweigh the perceived benefits. In this post, I will explain the perception of VPN security and its three often-overlooked real costs, drawing from my own experiences.
A VPN is fundamentally a technology that encrypts data communication by creating a secure tunnel over a network. This tunnel makes it harder for data to be monitored or altered externally, but it doesn’t mean it solves all security problems. Especially in corporate environments, the operation and management of a VPN often require more effort and resources than we anticipate.
Are VPN Connections Truly Secure?
Most people think, “I’m safe now” when they use a VPN. What I’ve seen in my 20 years of field experience is that the scope and limits of the security offered by a VPN are often misunderstood. A VPN encrypts a tunnel, yes, but it doesn’t directly make you responsible for the security of the systems and users at the ends of that tunnel.
A VPN connection ensures your data is transported securely from one point to another. This is vital, especially when using public Wi-Fi networks or when you want to prevent your Internet Service Provider (ISP) from monitoring your traffic. However, when you connect to a corporate network with a VPN, you usually gain broad access to the internal network. This means that if your VPN client or the device you’re connecting from is infected with malware, you could carry these threats into your corporate network through the tunnel. A secure tunnel doesn’t make traffic from a malicious device “good.”
While developing the ERP for a manufacturing company, we were using a VPN for remote access. Malware on a developer’s personal computer tried to infiltrate the company network via the VPN. Fortunately, thanks to our internal network segmentation and endpoint protection solutions, we didn’t experience a major issue, but this incident painfully demonstrated that a VPN alone is not a security guarantee. A VPN can only be one part of a well-structured security strategy, never the whole.
The First Real Cost of VPN: Why Is Complex Management and Scalability So Challenging?
The first and most prominent cost of VPN systems is the management burden and scalability challenges. Managing a few VPN users for a small team might be relatively easy, but when you reach hundreds or thousands of users, things can get out of hand. Individual configuration for each user, certificate management, defining and updating access policies require significant effort.
Especially as company policies change or new departments are added, keeping access rules on the VPN server up-to-date can become a nightmare. Granularly managing which user can access which internal IP addresses or ports is often a cumbersome and error-prone process in most VPN solutions. Ensuring synchronization between firewall rules and VPN policies is another headache.
graph TD;
A["New User Request"] --> B["Create VPN Configuration"];
B --> C["Generate and Distribute Certificate"];
C --> D{"Firewall Rule Needed?"};
D -- Yes --> E["Update Firewall Policy"];
D -- No --> F["Notify User"];
E --> F;
F --> G["User Establishes VPN Connection"];
G --> H{"Access Successful?"};
H -- No --> I["Troubleshooting and Support"];
H -- Yes --> J["User Starts Working"];
I --> G;
As you can see in the flow diagram above, even onboarding a new user to the system with a VPN can involve multiple manual steps. These steps are prone to human error and can lead to security vulnerabilities due to accumulating complexity over time. Especially when certificates expire or a user’s access is revoked, consistently applying changes across the entire system requires serious discipline. Investing in additional automation for these processes is also a separate cost.
The Second Real Cost of VPN: Why Do Performance and User Experience Decline?
The second significant cost of using a VPN is the often directly felt performance degradation. The encryption and decryption of data traffic itself creates a processing load. This process consumes CPU and memory resources on both the device running the VPN client and the VPN server. As a result, a natural latency occurs with every operation performed over the VPN.
This latency and the additional overhead on bandwidth become much more pronounced, especially when dealing with high-bandwidth applications or real-time communication (video conferencing, IP telephony). In a client project, I observed that file opening times significantly increased when users tried to access a remote file server via VPN. This not only reduced user productivity but also resulted in continuous performance complaints to the IT department.
Furthermore, the capacity of the VPN server is a critical factor. If the server lacks sufficient processing power or bandwidth, performance deteriorates further as the number of concurrently connected users increases. In such scenarios, we are forced to invest in more powerful hardware or additional VPN servers, which is an indirect cost. When managing a company’s egress traffic, I found that VPN traffic needed to be prioritized over other critical traffic with QoS (Quality of Service) settings, but even this couldn’t completely resolve the fundamental latency issue.
The Third Real Cost of VPN: How Does Broad Internal Network Access Conflict with the Zero-Trust Principle?
Perhaps the most insidious cost of a VPN is the broad internal network access it provides in most setups. Traditional VPN architectures typically allow a user, once authenticated and inside the tunnel, to access many resources within the corporate network. This “access to everything” or “access to much” approach completely contradicts the modern Zero-Trust security philosophy.
The fundamental principle in a Zero-Trust architecture is “never trust, always verify.” The identity and authorization of every user, every device, and every application are verified separately for each access request. Furthermore, access is granted only at the lowest necessary level (least privilege) and within the narrowest scope. In contrast, a VPN, once the user is inside the tunnel, typically assigns an IP address and can grant unrestricted access to internal network servers, databases, or other resources via this IP address.
graph TD;
subgraph "Traditional VPN Approach"
U1["User A (Remote)"] -- VPN Connection --> V["VPN Server"];
V --> N["Internal Network"];
N --> S1["Server 1"];
N --> S2["Server 2"];
N --> S3["Server 3"];
style V fill:#f9f,stroke:#333,stroke-width:2px
style N fill:#ccf,stroke:#333,stroke-width:2px
end
subgraph "Zero-Trust Network Access (ZTNA) Approach"
U2["User B (Remote)"] -- Authentication --> G["ZTNA Gateway"];
G -- Based on Policy --> S4["Only Server 4"];
G -- Based on Policy --> S5["Only Server 5"];
G -- X --> S6["Server 6 (No Access)"];
style G fill:#fcf,stroke:#333,stroke-width:2px
end
In the diagram above, a VPN user can access multiple servers once inside the internal network, whereas a ZTNA user accesses only specific servers according to defined policies. This broad access, if a single VPN account is compromised, facilitates an attacker’s lateral movement within the internal network and can put the entire company at risk. In a scenario I observed on a corporate bank’s internal platform, a external consultant connected via VPN had access permissions that, while intended only for a specific application, also allowed access to other test environments on the network. This situation was detected and quickly corrected thanks to my anomaly-based monitoring systems, but the potential risk was quite significant.
Are There Alternatives to VPN? How Does Zero-Trust Network Access (ZTNA) Make a Difference?
Given the costs and security vulnerabilities of VPNs that I’ve discussed, modern remote access strategies are shifting towards alternatives like Zero-Trust Network Access (ZTNA. Unlike VPNs, ZTNA verifies each access request individually and applies the principle of least privilege, regardless of where the user is or which network they are connected to.
In a ZTNA architecture, users do not connect directly to the corporate network. Instead, access to specific applications or resources is provided through a ZTNA gateway or a cloud-based service. This gateway continuously checks the user’s identity, the device’s status (up-to-date patches, anti-virus status, etc.), and the access policy. If all conditions are met, the user can only access the specific resource they requested. This significantly reduces the attack surface.
While developing the backend for my side product, I implemented an egress control similar to a ZTNA approach, especially when different services needed to operate in isolation from each other and only specific APIs needed to be externally accessible. This allowed each service to communicate only with specific targets, minimizing the risk of spread in case of any security breach. ZTNA, unlike VPN, extends network segmentation and microsegmentation to remote access scenarios, making the security architecture much more robust.
When Should We Use a VPN, and When Is a Different Approach Needed?
After discussing the costs of VPNs and their conflicts with the Zero-Trust architecture, the natural question arises: “Should we abandon VPNs entirely?” The answer depends on the situation. There are still scenarios where a VPN is valid and even the most suitable solution. The important thing is to make an informed choice.
VPNs are still very effective, especially for site-to-site connections, i.e., creating a secure tunnel between two fixed networks. For example, VPN tunnels are frequently used to establish secure communication between a headquarters and a branch office or to encrypt data traffic between different cloud providers. In such scenarios, the management burden is also lower, as there are usually fixed IP addresses and fewer variable users. Additionally, some legacy systems or specialized hardware only allow network-level access, so using a VPN to provide temporary access to these systems can be practical.
However, for large and dynamic user bases, especially as the number of remote workers increases, the management burden, performance issues, and security risks of VPNs multiply. In these situations, modern approaches like ZTNA (Zero-Trust Network Access) or SASE (Secure Access Service Edge) offer much more cost-effective and secure solutions. While this transition requires a one-time investment, it reduces operational costs and significantly strengthens the security posture in the long run. In my own experience, I’ve seen hybrid models used in the initial stages of transitioning to ZTNA, combining it with existing VPN infrastructure. This allows for a gradual transition, maintaining support for older systems while adapting to the new security paradigm.
Conclusion
While VPNs have played an important role in our digital world for many years, there are significant differences between our perceptions of them and their true costs. Although many companies still view VPNs as a “security shield,” factors such as complex management, performance degradation, and broad internal network access that conflicts with Zero-Trust principles are the overlooked real costs of VPNs. These costs manifest not only as money but also as IT team time, user productivity, and potential security risks.
My recommendation is to stop viewing VPNs as a silver bullet and instead evaluate them as part of a broader security architecture. Especially in large and dynamic environments, modern solutions like Zero-Trust Network Access (ZTNA) can address VPN’s weaknesses by offering much more granular access control, enhanced visibility, and a reduced attack surface. Remember, the best security solution is the one that best suits your needs and is implemented correctly. In future posts, I will delve deeper into the Zero-Trust architecture.