ZeroTier is considered secure for most use cases, but like any networking solution, its security depends on proper configuration and usage. Here’s a breakdown of its security aspects:

Encryption & Authentication

✅ End-to-End Encryption:

  • Uses AES-256 encryption for all network traffic.
  • Each node has a unique cryptographic identity using Curve25519 keys.

✅ No Centralized Decryption:

  • ZeroTier’s servers help establish connections but cannot see your traffic.
  • Even if ZeroTier’s infrastructure is compromised, your traffic remains encrypted.

✅ Mutual Authentication:

  • Uses public-private key pairs for device authentication.
  • Nodes don’t trust each other automatically unless authorized.

Attack Surface & Security Model

✅ No Open Ports Required

  • Uses peer-to-peer (P2P) networking, meaning it doesn’t expose services to the public internet.
  • Works even behind NAT and firewalls without requiring port forwarding.

✅ Minimal Attack Surface

  • ZeroTier runs as a user-space application, reducing kernel-level security risks.
  • The protocol is designed to resist MITM (Man-in-the-Middle) attacks.

⚠️ Potential Weakness: Centralized Root Servers

  • ZeroTier relies on its root servers (run by ZeroTier Inc.) for initial peer discovery.
  • If these servers were compromised or went offline, new connections might be affected.
    (However, already-established direct connections remain active.)

Security Concerns & Mitigations

🔹 Can ZeroTier See My Data?

  • No—all traffic is end-to-end encrypted.
  • ZeroTier’s root servers only help route traffic but cannot decrypt or inspect it.

🔹 Can Someone Else Join My Network?

  • No, unless explicitly authorized.
  • By default, ZeroTier requires manual approval of new devices in your ZeroTier Central dashboard.

🔹 What If My ZeroTier Account is Compromised?

  • If someone gains access to your ZeroTier Central account, they could add/remove devices from your networks.
  • Use a strong password + two-factor authentication (2FA) to protect your account.

Comparing ZeroTier to VPNs

Feature ZeroTier Traditional VPNs
Encryption AES-256 (End-to-End) AES-256 (Server-Side)
Peer-to-Peer ✅ ❌
No Public IP Exposure ✅ ❌ (VPN Servers Exposed)
Works Behind NAT ✅ ❌ (Port Forwarding Needed)
Centralized Control Partial (Root Servers) ❌ (Self-Hosted VPN Possible)

Best Practices for Secure ZeroTier Usage

✔ Enable Access Control → Require manual approval for new devices.
✔ Use Firewall Rules → Restrict traffic between nodes if needed.
✔ Use a Strong ZeroTier Account Password + 2FA
✔ Monitor Logs & Devices → Regularly review connected devices in ZeroTier Central.
✔ Self-Host Your Own Controller → If you don’t trust ZeroTier’s root servers, you can run your own.

Conclusion: Is ZeroTier Safe?

Yes, ZeroTier is secure when properly configured. It’s safer than many traditional VPNs because it:

  • Uses end-to-end encryption
  • Has no open ports
  • Works peer-to-peer, minimizing external exposure