Remote SDR Security Checklist

[Pavel]

Short answer: Keep SDR control and raw-I/Q services on a private network, reach them through a VPN, use unique accounts and restrict each service to the minimum interface and permissions. Do not expose an unauthenticated SDR server directly with router port forwarding.

Before you start​

• Prove the SDR on the Raspberry Pi interactively before turning it into a service. Record the device serial, USB path, driver and sample rate.
• Use a power supply, cable and USB topology that can support the Pi and every attached SDR under sustained load.

Step-by-step method​

1. Step 1: Inventory every listening port and bind management interfaces to localhost, LAN or VPN addresses. Disable default credentials and unused web panels.
2. Step 2: Patch the operating system and SDR server, then create least-privilege service users. Store API keys outside public configuration backups and screenshots.
3. Step 3: Use a VPN for remote clients, firewall the SDR ports to the VPN subnet and disable public UPnP or manual forwards. Test from an external network.
4. Step 4: Enable logs, rate limits where supported and alerts for repeated logins or service failure. Back up configuration without private keys and test restore.

Concrete example​

The internet-facing surface can be only the maintained VPN endpoint; OpenWebRX, SDR++ Server and device administration remain reachable solely through the VPN. This also avoids exposing precise station behavior and hardware control.

How to judge the result​

The checklist passes when an external scan cannot reach SDR services, authorized VPN clients can connect and revoking one client removes its access without changing every server password.

What to record​

• Run a sustained stream while monitoring undervoltage, USB resets, CPU temperature, dropped samples and storage growth.
• A headless service should restart cleanly, wait for networking and the SDR, write bounded logs and expose a health check.
• For remote access, prefer a VPN and least-privilege accounts instead of exposing receiver-control ports directly to the internet.

Common mistakes​

• Changing several hardware, software or RF variables at once, which removes the controlled comparison needed to identify the cause.
• Treating one autoscaled screenshot or one unusually good result as proof without recording the settings and repeating the test.
• Hiding a service on an unusual port is not authentication and does not prevent automated discovery.

Final check​

Reboot the Raspberry Pi and reproduce the complete service or stream without an interactive login. Check power, USB, logs, storage and remote access before leaving it unattended.