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Mozilla Sync Server

Mozilla Sync Server allows you to sync bookmarks, passwords, settings, history, add-ons, and tabs across multiple Firefox devices.

Supported Clients

  • Desktop: Firefox 42+
  • Mobile: Firefox 44+ (Android) and Firefox 18+ (iOS)
  • Forks: Compatible with Iceweasel and similar alternatives

Installation

During installation, you'll be prompted to enter the MariaDB root password to create a database for storing synced data.

Choosing Your Public URL

You must choose either an internal IP or an external domain name.

Use Case URL Format Desktop? Mobile?
Internal-only (Local Sync) http://192.168.1.100:8132 ✅ Yes ❌ No
External + Mobile Access https://example.com:8133 ✅ Yes ✅ Yes

Note

Mobile clients require HTTPS. If you plan to sync Firefox on mobile devices, you must use an external domain with SSL.

After Installation

The Sync Server will be available at: - Internal setup: http://192.168.1.100:8132/1.0/sync/1.5 - External setup: https://example.com:8133/1.0/sync/1.5

Testing Installation

Entering the Sync URL in a browser will return an "Unauthorized" error. To verify the server is running, visit:

http://192.168.1.100:8132/__heartbeat__

Configuring Firefox

Desktop Clients

  1. Open Firefox and go to about:config
  2. Search for identity.sync.tokenserver.uri and update it to: 
    http://192.168.1.100:8132/1.0/sync/1.5
    (For Firefox 42 or earlier, use services.sync.tokenServerURI instead)
  3. Open the menu in Firefox and click Sign in to Sync. Follow the prompts.
  4. Repeat step 2 on additional devices before signing in with the same account.

Android Clients

  1. Enable the debug menu before signing in:
  2. Go to Settings > About Firefox and tap the Firefox logo five times until you see "Debug menu enabled"
  3. Open Settings > Sync Debug, then set:
  4. Custom Sync Server: https://example.com:8133/1.0/sync/1.5
  5. Tap ✕ Stop Firefox in the menu, then reopen the app
  6. Sign in via Settings > Synchronize and Save Data

iOS Clients

  1. Enable debug settings before signing in:
  2. Go to Settings > About and tap the version number five times until a Debug section appears
  3. In Account > Advanced Sync Settings, set:
  4. Custom FxA Content Server: https://accounts.firefox.com
  5. Custom Sync Token Server: https://example.com:8133/1.0/sync/1.5
  6. Go to Settings > Account > Synchronize and Save Data, then sign in

Enabling SSL (HTTPS)

Mozilla Sync Server does not natively support SSL. Use Synology DSM's built-in reverse proxy.

Prerequisites

  • You plan to use HTTPS (https://example.com:8133)
  • You have a domain name resolving to your Synology's public IP
  • A valid SSL certificate is installed on your Synology DSM

DSM Reverse Proxy Setup

  1. Open DSM Reverse Proxy Settings:
  2. DSM 6: Control Panel > Application Portal > Reverse Proxy
  3. DSM 7: Control Panel > Login Portal > Advanced > Reverse Proxy
  4. Create a new reverse proxy rule:
  5. Description: Mozilla Sync Server
  6. Source:
    • Protocol: HTTPS
    • Hostname: example.com
    • Port: 8133 (or 443 if available)
    • Enable HSTS
  7. Destination:
    • Protocol: HTTP
    • Hostname: localhost
    • Port: 8132
  8. Save and apply the changes

Router & Firewall Configuration

To allow external access:

  • Open port 8133 in Synology's firewall (Control Panel > Security > Firewall)
  • Forward port 8133 on your router/firewall to your Synology NAS
  • Ensure your domain resolves to your public IP
  • For internal access, configure an internal DNS record mapping your domain to your Synology's local IP

Troubleshooting

Checking Logs

Firefox logs sync errors at: about:sync-log

To enable success logs, go to about:config and set: 

services.sync.log.appender.file.logOnSuccess = true

Common Errors

Mobile Clients Can't Connect

  • Firefox mobile requires HTTPS. Ensure SSL is set up properly.
  • iOS login fails with a blank page: Ensure Custom FxA Content Server is set to https://accounts.firefox.com (no trailing slash)

References