What Is The Difference Between VPN And VNC?

What Is The Difference Between VPN And VNC?

Updated: 08-14-2021

Many people confuse Virtual Network Computers (VNCs) with Virtual Private Networks (VPNs) even though the two have different functions. But even before we dig into that, here's what to expect in this article.

You'll learn:

  • How VNCs and VPNs work.
  • Differences between VPNs and VPNs.
  • Advantages and disadvantages of VNCs and VPNs.
  • Choosing the better option between a VNC and VPN.
  • And more.

A Virtual Network Computer (VNC) is an open-source tool that uses Remote Buffer protocol (RFB) to connect multiple clients to a VNC server. The RFB protocol allows remote access to Graphical User Interfaces (GUI) by enabling the client to view and control a remote desktop.

With a VNC, you can remotely control another computer over the same network. A VNC transmits keystrokes and mouse clicks from a thin client computer to a thick client computer.

A thin client is a low-performance computer optimized to establish a remote connection with a VNC server. Thin clients run resources from a central server instead of a local hard drive.

Compared to regular PCs, thin client computers have minimal resources with no local storage. On the other hand, a thick client is a full-featured computer connected to a network and has its own storage and features.

This computer does not require a server connection to run and remains functional even when disconnected from the main network.

VNC servers use the RFB protocol to update the frame buffer displayed on a thin client computer.

A framebuffer is an area of memory that holds data continuously being transmitted to the screen.

On the other hand, the RFB protocol is an independent technology operating at the framebuffer level; therefore, it can run on all major Operating Systems (OS) and Internet protocols.

However, it is platform-dependent, meaning that a thin client computer operating on one type of OS can’t connect to a VNC server operating a different OS.

There are several VNC variants with their own functionalities and different clients and servers for operating systems based on Graphical User Interface (GUI).

How a VNC Works

A VNC connects a client and server over the same network. When a connection is established, the server requests authentication from the client by prompting a password from the thin client computer.

This form of authentication is called the challenge-response scheme and helps prevent unauthorized users from accessing server resources.

VNCs use a client-server model of networking, which has better flexibility because connections are not fixed and are expandable to handle multiple clients simultaneously.

Also, management of all server resources happens in a centralized location. The network protocol in a VNC connection is RFB, allowing clients to access the graphical user interface from a server remotely.

The server establishes a connection when the client responds with the correct password. Then, the client selects the encoding scheme, pixel format, and desktop size, then requests a physical display from the server.

The session begins when the server updates the local display of the framebuffer contents and shares them with the client. Remote client input is then translated to local input on the server.

A broadband connection facilitates communication between the client and server if they’re using VNC over the internet. A connection can only be successful if there’s a reliable transport protocol, either Transmission Control Protocol (TCP) or Internet Protocol (IP), and a pixel display method. VNC connections usually go to TCP port 5900+ N, where N represents the physical display number.

You can use different TCP port assignments as long as the client and server are configured correctly. The server provides pixel data in the format selected by the client. When VNC establishes a connection, the client can take full control of the server remotely.

What Are VNCs Used For?

Organizations that value reduction in security exposure use VNCs because the data center environment is always locked down. A client can access the data center only with the correct password for authentication.

Using thin clients is cost-effective for most organizations because they don’t require the maintenance and management costs incurred when using traditional PCs.

It’s much easier to maintain a VNC because of the centralized administration and policy-centric control. Also, troubleshooting the entire system can be done with a single click.

A VNC is scalable over a global enterprise because users are connected to a distributed architecture and can receive multiple server support at any moment.

With VNCs, users can access files remotely by connecting their thin clients to the workplace server.

System administrators or IT support can control an employee’s computer remotely if the employee needs help with any program.

Educational institutions can use VNCs to screen share and allow students to see what their tutors are doing.

What Are the Downsides of VNCs?

As much as VNCs come with many benefits, they also have their downsides.

Let's take a look at some of the most common.

Excessive Bandwidth Usage

VNCs tend to work well in a network with stable and high bandwidth. A decrease in upstream bandwidth causes buffering and network delays caused by TCP round-trip delays (RTD).

An RTD is the time taken for a signal to be sent and acknowledged after arrival.

If you’re using a network with low bandwidth and high latency, it’s advisable to reduce the resolution and use grayscale screens. VNCs consume a lot of bandwidth; therefore, you need a strong network connection if you intend to use real-time programs and any other interactive applications.  

Security Threats

Though not common, if a thin client computer contains a virus, it can infect the entire network. Vulnerabilities are not common on the server-side because an attack on the server is impossible without proper authentication.

Performance Issues

Most VNC software uses raw encoding, a slow and primitive encoding technique considering the raw screen is sent pixel-by-pixel. When the entire screen changes, it affects performance, and the system runs slower.

Limited Application Usability

You can only launch an application installed on the thick client. To access a local application remotely, you’ll need to install it on the thick client first.

Significance of VNCs

With a VNC, you can run a recent program on an old computer system. This is because thin client computers do not require a lot of physical memory, given that the server handles the processing.

When physical access to the workplace is difficult due to unavoidable circumstances such as natural disasters, organizations can use VNCs to continue their daily activities.

It’s easier to restore lost data if a thick client computer is destroyed, and this is because VNC stores data in a secondary data center. Therefore, in the event of a disaster, there's no disruption of normal workflows in an organization because data is retrievable from an external server.

Types of VNC

VNCs come in different forms — more on this below.

Tight VNC

This is a free software that consists of special data encoding techniques and has GPC licensing features. It’s easy to use and supports lower-speed network connections.

The software, released in 2011, has file transfer capabilities that only work for Windows OS.

A Java version of the software is available but not commonly used. The software is also available for UNIX and compatible with other VNC applications.

Even though it consumes little system resources, Tight VNC uses more network resources than other VNC software in the market. Also, the application’s interface seems a little bit outdated and lacks advanced features available in other VNC software.

Features of Tight VNC

  • Allows users to scale a remote desktop locally by changing the size of the display.
  • Users can disable the remote Dots Per Inch (DPI) scaling, which is the number of individual dots placed within a space of one inch.
  • Has an enhanced web browser access.
  • Allows progressive JPEG image compression with efficient encoded components in multiple scans.
  • Allows users to create and change passwords to help improve security. Has no predefined default password; therefore, the administrator has to set user-specific passwords after installation.

Ultra VNC

Ultra VNC is an open-source software mainly used by mainstream companies and enterprises. The client-side of the software supports both Windows and Linux, but the server-side only supports Windows.

You first need to install the Ultra VNC application on the server and client devices to use the software.

Features of Ultra VNC

  • Allows file transfer functions such as sending and receiving files to and from the server.
  • Allows for image compression enhancement and processing.
  • Has live chat capabilities for easy and quick communication from the client to the server.
  • Remote access to emails.
  • Allows clients to control a single program remotely.


This software is written entirely in C# language and compatible with smartphones, Personal Digital Assistants (PDAs), pocket PCs, and Windows desktops. It can run on different modes, such as:

  • Window mode
  • Full-screen mode
  • Listen mode


  • Scalable distributed architecture on the client and server-side.
  • Supports pocket computers and handheld devices.
  • Stores session history.

Real VNC

Original VNC creators developed Real VNC for multiple platforms. You can easily connect to any VNC client using a Real VNC server. It is lightweight, but the configuration process is more complex than other VNC software.

The software suits business owners but also offers a home subscription for non-commercial use.

Commercial versions of the software include professional and enterprise editions.

Tiger VNC

Tiger VNC is an open-source client/server application based on the fourth generation of Tight VNC. It allows users to establish a VNC connection and interact with the graphical applications stored in a workstation or data center. Users can establish connections on multiple computers connected over the same network.

This VNC software has an easy-to-use control panel that shows the machine’s IP address, status, and connection time. The software supports several video encoding types and is suitable for running 3D applications.

Additionally, users can enter a custom compression level, including JPEG compression.

Tiger VNC supports Windows, Linux, and Mac on the client-side but only supports Linux on the server-side. Users can also download and install various extensions for advanced authentication and security.

Are VNCs Secure?

VNCs can be vulnerable to a Denial of Service (DOS) attack if the attacker opens more than 60 connections to a Hypertext Transfer Protocol (HTTP) port simultaneously.

A DOS attack is a cyber-attack in which the attacker seeks to make the server unavailable to thin clients by disrupting the services of the thick client.

If the attacker is successful, the VNC service crashes, preventing all legitimate users from logging onto the system. This is because the VNC cannot establish a connection between the thin client device and the remote computer.

Some bugs in the VNC system allow remote code execution, therefore, leading to memory corruption vulnerabilities. These vulnerabilities can be found in the client and server-side of the system. Such vulnerabilities are exploitable by an attacker who has access to the system after password authentication.

An attacker who has gained authorization into the system can execute malicious code using a VNC client device. But even if that happens, the attackers would need the authorization to infect the whole system.

Also, an attacker can read stack memory if there’s a memory leak in the server code that’s exploitable via a network connection. The attacker could end up leaking stack memory and bypassing Address Space Layout Randomization (ASLR).

ASLR is the security technique used to prevent the exploitation of memory and guards against buffer-overflow attacks.

An attacker can easily access VNC traffic sent over an unencrypted network if they have the right resources and skills. To ensure the integrity of data passing through a VNC, it is advisable to tunnel VNC traffic over Secure Shell Protocol.

Securing VNC Traffic With SSH

The SSH protocol connects users to a remote computer using a text-based interface. After establishing a secure SSH connection, a shell session begins. The thin client device then connects to the server using the provided remote host information.

After verifying the credentials, the SSH client establishes an encrypted connection, making it possible to manage the remote computer in a highly secure manner.


VPNs establish a secure connection over a private network to allow access to resources remotely. They can also secure internet traffic from prying eyes such as governments, Internet Service Providers (ISPs), and hackers. Some individuals even use VPNs to access geo-restricted or censored content.

Pros of a VPN

Hides private data: Using a VPN prevents sites from accessing your internet traffic and collecting your data, which protects and safeguards your personal information.

Stops and bypasses bandwidth throttling: Your ISP may throttle internet connection due to various reasons such as data caps, or paid prioritization. A VPN comes in handy in stopping and bypassing bandwidth throttling by ISPs. Using a premium VPN service will prevent your ISP from tracking your device and knowing what you do on the internet.

Protected file-sharing: With a VPN, members of an organization can share data within an encrypted network without worrying about hackers accessing or exposing the data.

Provides anonymity: A VPN hides your Internet Protocol (IP) address; therefore, whatever you do online won’t be traced back to you.

Bypass blocks and filters: A VPN can bypass blocked websites and internet filters in a region with internet censorship. Users can also access geo-restricted content on streaming sites such as Netflix by connecting to a VPN service that places their devices outside the blocked region.

Network scalability: Some organizations use VPNs to create secure tunnels of communication that employees can utilize to access resources in a cloud environment.

As a result, such organizations do not have to spend a lot of money expanding the network to accommodate more employees. All a new employee needs to do to access organization resources is to log in with the correct credentials.

Cost-effectiveness: A VPN that incorporates cloud computing architecture saves an organization a considerable amount of money that would otherwise be spent on the setup and maintenance of an in-house server.

Cons of a VPN

Lower Internet Speeds: The VPN encryption process takes time to materialize and, as a result, it can significantly reduce internet speed. This also depends on how far the VPN server is.

Connecting to a VPN server located far away from the client will mean slower internet speeds than connecting to a closer server. Also, the internet speed drops if too many users connect to the same server.

Complex configuration: Setting up a VPN service, especially in an organization, requires technical know-how. A VPN connection should be appropriately configured in such a setting.

In some cases, you may need the intervention of an Information and Technology expert.

Great VPNs cost money: Not all VPNs are safe to use, especially free versions.

You can't trust free VPNs; some may expose your device to malware, sell your data to third parties or track your online activity. On the other hand, premium VPN services subject users to monthly subscription costs, which can be expensive in the long run - but entirely worth it.

What’s the Difference Between a VPN and VNC?

By now, you know that VPNs and VNCs are two different things. But how exactly are they different from each other?

Here's how:

A VPN encrypts data and establishes a protected network connection. On the other hand, a VNC is ideal for individuals or businesses that want to access a remote desktop from a thin client device.   

VPNs create a private network over a public one, while VNCs control a remote computer over a network.

You can set up VPNs to allow work-related connections by delegating the remote computer as part of the network. On the other hand, VNCs don’t necessarily need the remote computer to be part of the network to enable a user to connect from a thin client device.

Installing and configuring an organization’s VNC is much easier than setting up a VPN in the same organization. Often, configuring a VPN in an organization requires the help of an expert because if it’s not configured correctly, the network might be vulnerable to attacks.

VPNs are more secure because they’re automatically encrypted, while VNCs require installing essential security features and correct configuration before being considered safe to use.

VNCs can restrict user access to certain functionalities in a remote computer, e.g., disabling the transfer of files. Therefore, a VNC administrator can prevent the transfer of sensitive data from a remote computer. VNCs have a separation of environment advantage; a VNC client can only access information allowed by the remote computer.

Unfortunately, a VPN cannot restrict what a user shares over a network. In such a scenario, a corrupted file can be transferred over a network.

VNCs allow users to remotely access, interact and operate a remote desktop as if it’s right in front of them, but VPNs lack this capability. VPN users need their own computers to access resources available on a shared network.

Which Is Better: VNC vs VPN?

Virtual Private Networks (VPNs) can encrypt a VNC connection via a remote network to prevent the exposure of internet traffic to the outside world. Using a VPN is an excellent way to maintain data integrity and anonymity online. On the contrary, you don’t need a VPN if your VNC software is fully encrypted and has multi-factor authentication.

The main difference between VNCs and VPNs is that VNCs use the Remote Framebuffer protocol to aid graphical screen-sharing technology. This protocol enables a client/viewer to control another computer connected to a server or remote workstation.

On the other hand, VPNs allow users to route their internet traffic through a secure tunnel connecting them directly to their organization’s network. It also encrypts the data sent over the network to prevent outsiders from accessing it.

Both VNCs and VPNs allow users to access local applications on a remote computer. A VNC is ideal for organizations or individuals who need to facilitate accessibility between a thin client and a remote desktop. If you’re more concerned about maintaining privacy and anonymity over the internet, then a VPN would be a great option to consider.

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28 comments on “What Is The Difference Between VPN And VNC?”

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