10: Syncthing - File Synchronization

Syncthing keeps folders on your devices in sync (PCs, servers, laptops). It’s private, fast, and peer‑to‑peer. For detailed usage and device pairing guides, see the official Syncthing documentation.

Dependency check

• Required: Docker (Chapter 3)
• Optional: Traefik (Chapter 4) + subdomain (Chapter 4.5) for easy HTTPS access
• Optional: Borgmatic (Chapter 6) to back up Syncthing data

What is Syncthing? (Simple Explanation)

Syncthing lets you pick a folder (e.g., Documents) and keep it automatically synchronized between your devices. You choose which devices and folders to sync—nothing is uploaded to third‑party clouds.

Interdependencies

Optional but recommended: Traefik for secure HTTPS access with your domain (easier to reach your server). Borgmatic will back up Syncthing data as part of your regular backups.

Prerequisites

• ✅ Docker running (Chapter 3)
• ✅ Optional: Traefik installed (Chapter 4) + subdomain (Chapter 4.5), e.g., sync.yourdomain.com
• ✅ Optional: Borgmatic installed (Chapter 6) for backups

Step 1: Start Infinity Tools

sudo infinity-tools

Step 2: Install Syncthing

1. Go to 📱 APPLICATIONS
2. Select Syncthing
3. Choose Install Syncthing

Using the Infinity Tools GUI

• Use ↑/↓ to move, Enter to select, Esc to go back
• Look for the turquoise cursor indicating the current selection
• Each screen shows a short description at the top explaining what’s needed

Step 2.1: Choose SSL Mode

You’ll be asked how you want to access Syncthing’s web interface:

• Traefik (recommended)
  • What it is: Use your domain with a trusted HTTPS certificate
  • What you need: Subdomain like sync.yourdomain.com pointing to your server
  • What you get: Clean URL like https://sync.yourdomain.com
  • Pick this if: You want easy, secure access from anywhere
• Standalone HTTPS (self‑signed)
  • What it is: HTTPS with a self‑signed certificate (browser warning appears once)
  • What you need: A free port (e.g., 8384)
  • What you get: URL like https://SERVER_IP:8384
  • Pick this if: You use it only within your home/office network
• Standalone HTTP (not encrypted)
  • What it is: Plain HTTP
  • Pick this only if: Quick local testing on a private network

Rule of thumb: Use Traefik if you have a domain. Otherwise use Standalone HTTPS for local networks.

Step 3: Open Syncthing

• Traefik mode: Visit https://sync.yourdomain.com
• Standalone: Visit https://SERVER_IP:8384 (or the port you chose)

Step 4: First‑Time Basics

1. Change the GUI password: In Settings → GUI, set a username/password
2. Set the device name: Give your server a friendly name (e.g., “Home‑Server”)
3. Create your first folder: Click “Add Folder” → pick a folder path (e.g., /opt/speedbits/syncthing/Documents)

Step 5: Pair a Device

1. Install Syncthing on your computer/phone (see official downloads)
2. On your device, copy the Device ID (a long string)
3. On the server web UI, click “Add Remote Device” → paste the Device ID → give it a name
4. Accept the pairing request on the other device
5. Share a folder: Select your folder → “Share With Devices” → pick the device you added

Step 6: Verify It Works

• Create a test file (e.g., Test.txt) in the synced folder on one device
• Within seconds, the file should appear on the other device

Troubleshooting

• Can’t open the web UI? Check the URL/port and that the Syncthing container is running: docker ps | grep syncthing
• Browser warning? That’s normal for self‑signed HTTPS—accept once to proceed
• Folder not syncing? Make sure both devices shared the same folder and have write permissions
• Firewall issues? Ensure ports are open or use Traefik mode for easier access

Quick Reference

• Web UI (Traefik): https://sync.yourdomain.com
• Web UI (Standalone): https://SERVER_IP:8384
• Change GUI password: Settings → GUI

You’re ready to keep your files in sync across devices—privately and securely.