How Does a VPN Work

KZero Staff
Jul 27, 2023

What is a VPN?

A virtual private network (VPN) creates an encrypted tunnel between two points for traffic to flow over. VPNs can be used to link a remote user to a corporate network, to connect two company networks, or to protect a consumer’s privacy against eavesdropping by their ISP or the operator of a Wi-Fi network.

VPNs can be implemented in a few different ways. Some of the most common VPN protocols include IPsec and SSL VPNs.

How Does a VPN Work?

A VPN is designed to create a secure tunnel between two points. All traffic flowing over the VPN is encrypted, which helps to protect against eavesdropping and other potential threats of using VPNs.

A VPN tunnel is set up via the following process:

  • Authentication: Typically, a VPN will require the user to authenticate to the VPN server and may require mutual authentication of the client and the server. A VPN client may authenticate using passwords, digital certificates, or similar means.
  • Setup: Before the two communicating parties can create a secure tunnel, they need a shared secret key. This key could be shared in advance or be established using a key exchange protocol.
  • Encryption: Once the shared key is established, all traffic flowing over the VPN tunnel will be encrypted. The sender of a message will encrypt it using the shared secret key before sending it out over the network.
  • Decryption: When the party at the other end of the VPN connection receives a message, they will decrypt it with their shared secret key. This allows them to read the message and generate a response, which they will send back encrypted.

Advantages and Disadvantages of VPNs

VPNs are a common remote access solution and enjoyed increased adoption during the surge in remote work. Some of the advantages that VPNs provide include:

  • Confidentiality: All traffic flowing over a VPN is encrypted. This protects against an attacker intercepting and reading network traffic en route to its intended destination.
  • Security: Public Wi-Fi networks have various potential risks. VPNs help to protect against these threats by protecting a computer’s traffic from the rest of the VPN users.
  • Geoblock Bypasses: Some systems are designed to only permit access from certain locations or geographic regions. A VPN can provide a remote user with access without removing these restrictions.

However, VPNs also have their downsides as well, including:

  • Complexity: VPNs provide connectivity between two points. As corporate networks grow more complex with multi-cloud deployments, this results in complex VPN infrastructure.
  • Latency: VPNs often incur significant network latency. This is due to the encryption/decryption process and inefficient routing as companies try to make VPNs work for complex networks.
  • Security Integration: VPNs provide an encrypted connection and nothing else. They do nothing to inspect the traffic traveling over them for malicious content and other threats.
  • Access Controls: VPNs provide remote workers with unrestricted access to the enterprise network. Organizations must implement additional access controls to manage the risk of compromised accounts.


VPNs provide remote users with secure, encrypted connectivity to a remote site. They are commonly used to support a remote workforce or to safely use public Wi-Fi and other untrusted networks.

KZero Staff

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