Prevent IP Leaks

This module is used to block IPv6 and DNS requests outside the VPN tunnel.

What is a Prevent IP Leaks module

When developing VPN applications, it's crucial to ensure that users' IP addresses remain hidden and secure. IP leaks can expose users' real IP addresses, compromising their privacy and security. In this article, we'll explore how to prevent IP leaks using an SDK that provides IP leak prevention functionality.

An IP leak occurs when a VPN user's actual IP address is revealed, despite the active VPN connection. To minimize these risks, VPN applications must incorporate robust IP leak prevention mechanisms specifically designed for DNS and IPv6 traffic.

Default Windows DNS client sends DNS requests through the all network interfaces in the same time and waits which one will answer first. Even when you use Google DNS servers on your primary network adapter, they are located in different countries and the closest one will answer first and often it will be DNS server that is closest to your primary network interface, not a tunnel.

The same thing with IPv6 when VPN servers don't support IPv6. By default Windows prefers to use IPv6 over IPv4 and when sites have both IPv4 and IPv6 addresses then client machine will send traffic outside the tunnel.

Enabling Prevent IP Leaks

In our VPN SDK, the Prevent IP Leaks feature can be enabled in two ways:

1. By setting the EnablePreventIPLeak parameter:

• When starting the VPN connection, set the EnablePreventIPLeak parameter to true in the StartVpnRequest object:

var startVpnRequest = new StartVpnRequest()
{
    AccessToken = loginResponse.AccessToken,
    Credentials = getCredentialsResponse.Credentials,
    EnableKillSwitch = false,
    VpnNode = node,
    EnablePreventIPLeak = true, // Optional, enabled by default
};
    
var startVpnResponse = sdk.StartVpn(startVpnRequest);

1. By calling the EnablePreventIpLeak/EnablePreventIpLeakAsync methods:

• Directly call the EnablePreventIpLeak or EnablePreventIpLeakAsync method on the SDK instance:

///Enables prevent IP leak module.
var enableResponse = await sdk.EnablePreventIpLeakAsync().ConfigureAwait(false);

Disabling Prevent IP Leaks module

To disable the Prevent IP Leaks feature, you can use one of the following methods:

1. By setting the EnablePreventIPLeak parameter:

• When starting the VPN connection, set the EnablePreventIPLeak parameter to false in the StartVpnRequest object:

var startVpnRequest = new StartVpnRequest()
{
    AccessToken = loginResponse.AccessToken,
    Credentials = getCredentialsResponse.Credentials,
    EnableKillSwitch = false,
    VpnNode = node,
    EnablePreventIPLeak = false, // Disabling Prevent IP Leaks module
};

1. By calling the DisablePreventIpLeak/DisablePreventIpLeakAsync method:

• Directly call the DisablePreventIpLeak or DisablePreventIpLeakAsync method on the SDK instance:

///Disables prevent IP leak module
var disableResponse = await sdk.DisablePreventIpLeakAsync().ConfigureAwait(false);

By following these steps, you can easily enable or disable the Prevent IP Leaks feature in our VPN SDK, ensuring the protection of users' IP addresses while connected to the VPN.