Troubleshooting Rsync Error: Protocol Data Stream (Code 12) on Windows 10 and Raspberry Pi

Troubleshooting rsync Error: Protocol Data Stream (Code 12) on Windows 10 and Raspberry Pi

If you're working with rsync 3.3.0 on a PC running Windows 10 and rsync 3.2.7 on a Raspberry Pi 4 with Debian Linux, you may encounter the error "Protocol Data Stream (Code 12)" during file transfer. This article will help you understand the issue and guide you through the troubleshooting process.

Understanding the Protocol Data Stream (Code 12) Error

RSync, a powerful file synchronization and backup utility, typically operates between two hosts using the rsync protocol. Commonly, rsync uses SSH as its transport mechanism. However, during file transfer, you may receive the following error:

This error occurs because the stream of data transfer is interrupted or broken, indicating a connection issue between your PC and Raspberry Pi. Below are some key concepts and solutions to help you resolve this issue.

Key Concepts and Considerations

Check Your SSH Keys

To ensure seamless communication between your Windows 10 PC and Raspberry Pi, verify the SSH keys are properly configured. Specifically, the Raspberry Pi should accept the keys from the Windows 10 PC. Follow these steps to ensure SSH keys are appropriately set up:

1. On your Windows 10 PC, generate a new RSA key pair using ssh-keygen in the Cygwin terminal.
2. Copy the public key to the ~/.ssh/authorized_keys directory on the Raspberry Pi. You can perform this by:
• Using the ssh-copy-id command.
• Or, manually copying the public key from the PC to the Raspberry Pi.
3. Verify SSH keys work by launching the SSH client from your PC to the Raspberry Pi.

Network Stability

An unstable network connection between the PC and Pi can cause the Protocol Data Stream error. It is crucial to ensure both devices can maintain a stable connection. Consider the following:

• Use a wired Ethernet connection instead of Wi-Fi. Ethernet typically offers better connection stability.
• Check for cabling issues. Ensure that Ethernet cables are functioning correctly.
• Inspect your router and network devices. Check if there are firmware upgrades available for the network devices.

Resource Availability and Load

Fully loaded systems might cause connection issues, resulting in the Protocol Data Stream error. Monitor the load on both your Windows 10 PC and Raspberry Pi to ensure minimal load during file transfer.

Firewall Configurations

Firewalls on either device may block necessary ports or connections that rsync requires. Make sure the necessary connection ports, such as SSH (22) and rsync (873), are open and accessible for both the PC and the Raspberry Pi.

Troubleshooting Steps

1. Test SSH Connectivity

Before diagnosing the rsync Protocol Data Stream error, first verify SSH connectivity between your devices.

• Launch a terminal (Cygwin) on your Windows 10 PC.
• Enter the command ssh [user]@[pi-ip-address] and ensure you can connect without issues.

If you cannot connect through SSH, resolve the SSH issue before continuing.

2. Test Rsync Through SSH

Once SSH works flawlessly, verify rsync directly through SSH.

• On the PC, enter the following command:
rsync -avz -e ssh [source] [user]@[pi-ip-address]:[destination]
• If rsync transfers files via SSH without issues,

  Protocol data stream error is not related to rsync but rather a network or firewall configuration issue.

3. Analyze Network Settings

• On the Windows 10 PC and Raspberry Pi, disable any temporary firewalls and antivirus software.
• Check the network cables and connectors for any damage.
• Restart your router or modem for a clean network connection.

4. Rsync Configuration on Raspberry Pi

While rsync settings on the Raspberry Pi are unlikely to cause the error, verify they are proper.

• Check the rsync daemon on the Raspberry Pi by examining the /etc/init.d/rsync file.
• Ensure the Raspberry Pi can create directories on both ends. Modify the /etc/default/rsync file accordingly.
• Inspect the /etc/rsyncd.conf file for any misconfigurations.

• The rsync Protocol Data Stream (Code 12) error typically indicates a connection issue between your devices. SSH keys, network stability, resource availability, and firewall configurations are crucial elements to consider.
• Test SSH and rsync connections independently to the Raspberry Pi and assess each system's network settings.
• Verify your rsync configuration on the Raspberry Pi if necessary.

References

• rsync Manual
• Rsync Arch Linux Wiki
• Network Tools in Cygwin