# How to Detect VPN using Kotlin
VPNs aren’t inherently bad—but in mobile security, they often mask fraud, location spoofing, or data exfiltration. If your app deals with sensitive data, you need a way to know when a VPN is in play. Thankfully, there is tooling which makes VPN detection straightforward in Kotlin apps.
### What is VPN?
A **VPN (Virtual Private Network)** encrypts traffic and routes it through remote servers. While this protects privacy, it can also help attackers:
* **Bypass geo-restrictions** (e.g., accessing services from unsupported countries)
* **Hide malicious activity** like bot traffic or credential stuffing
* **Exfiltrate sensitive data** undetected
Attackers often use common VPN apps (NordVPN, ExpressVPN, ProtonVPN) or system-level tunnels to disguise their actions. From a security perspective, detecting VPN usage is like knowing if a user is “wearing a mask”—it doesn’t always mean they’re hostile, but it changes the trust level.
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Usage of VPN does **not** automatically impose threat.
{% endhint %}
### How to Detect VPN Usage?
Detecting VPNs isn’t trivial—many providers change IPs, use stealth protocols, or blend with normal traffic. DIY solutions (like hardcoding VPN IP ranges) are unreliable and outdated quickly.
Instead, use expert SDKs that:
* Actively monitor for VPN interfaces and tunnels
* Stay updated against new evasion techniques
* Provide callbacks so your app can respond instantly
### Popular Libraries for VPN Detection
#### freeRASP (by Talsec)
The robust, developer-friendly and free choice for Android.
* [Actively maintained](https://docs.talsec.app/freerasp/whats-new-and-changelog)
* Comes with [**14 extra detections**](https://docs.talsec.app/freerasp/wiki/threat-detection) like app integrity, runtime manipulation (hooking with Frida), emulators, debugging, screenshots, etc.
* Trusted by [**6000+ apps worldwide**](https://42matters.com/sdk-analysis/top-security-and-privacy-sdks#talsec)
**Integration Example:**
Add the [freeRASP](https://app.gitbook.com/s/Q2PxZTOjhquOxcxftTrm/freerasp/introduction) in your project, focus on implementing the following callback:
```kotlin
Talsec.start(applicationContext)
override fun onVpnDetected() {
Log.w("freeRASP", "VPN connection detected!")
// Optionally block sensitive actions or warn the user
}
```
**Malwarelytics for Android**
* Aside from VPN detection, it also contains additional security checks
* Enterprise grade of checks
* Might be expensive for small apps
**Integration Example:**
```kotlin
val raspObserver = object : RaspObserver {
// The callback is delivered on a background thread
override fun onVpnDetected(vpnEnabled: Boolean) {
// Handle VPN detection
}
// Handle detection of other RASP features
}
```
### Comparison Table
| Feature | freeRASP | Malwarelytics |
| ------------------------- | -------- | ------------- |
| Works Offline | Yes | Yes |
| Easy Integration | Yes | Yes |
| Broader Security Coverage | Yes | Yes |
| Free | Yes | No |
#### Commercial Alternatives
When evaluating mobile app security and Runtime Application Self-Protection (RASP), developers often compare various Talsec alternatives to find the right fit for their architecture. The "right choice" depends on the specific problem you need to tackle and which vendor offers the best **bang for your buck**.
The market is diverse, offering different philosophical approaches to protection. Talsec prioritizes top-tier root detection and a balanced security SDK portfolio covering the most popular attack vectors. Meanwhile, some vendors specialize primarily in heavy code obfuscation and compiler-based hardening, while others focus on a drag-and-drop (no-code) integration experience for DevOps-oriented teams. There are also solutions dedicated specifically to API security, active cloud hardening, enterprise compliance, or gaming protection. The most prominent providers alongside **Talsec** include **Guardsquare**, **Appdome**, **Promon**, **Build38**, **Approov**, and **AppSealing**.
### Key Takeaway
VPN detection is crucial for apps where fraud, compliance, or region-locking matter. Manual solutions fall short—but **freeRASP** gives Kotlin developers a lightweight, reliable SDK to stay ahead of attackers.
👉 If you want **VPN detection plus root, Frida, emulator, and tampering protection** in one free package, start with [**freeRASP by Talsec**](https://talsec.app/).
{% hint style="success" %}
Handle App Security with a Single Solution! Check Out Talsec's Premium Offer & Plan Comparison!
#### Apps Security Threats Report 2025
#### Plans Comparison
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{% endhint %}
