Transmission

Lightweight BitTorrent client that “just works”

Transmission is a fast, easy-to-use BitTorrent client designed with sensible defaults that work out of the box. Ubuntu chose Transmission as its default BitTorrent client largely due to its easy learning curve. QuickBox Pro installs the modern v4 (4.x+, Qt6-based) build by default on every supported distro, with the legacy v3 (3.00) available as an opt-in where it is still compiled. Every install ships per-user systemd services, an nginx reverse proxy, and pre-configured RPC access.

Installation

Install from the Dashboard

Open App Dashboard → Package Management (/dashboard?mode=packages), find Transmission in the catalog (browse Download Clients or search), and click Install. The version selector defaults to the latest (v4) build for a new install; the legacy 3.x series appears as a choice only on distros where it is still compiled (Debian 12 and Ubuntu 22). The dashboard streams the install log live and Transmission appears in your Application Control panel when it finishes. Reinstall, Update, and Remove are available from the same panel.

When you update an existing install, the dashboard keeps the major you already have — a v3 install stays on v3 unless you explicitly pick v4 in the selector. Picking v4 migrates the install for all users.

What you see and can manage is gated by your account: admins manage any user’s apps; regular users manage their own. For the full package flow see App Management.

Install from the CLI (automation)

The CLI runs the same install and is suited to automation and scripting. By default it installs the modern v4 (4.x+, Qt6) build; add --v3 to install the legacy 3.00 build where it is available. --v4 is accepted as an explicit alias for the default:

qb install transmission -u username          # modern v4 (default)
qb install transmission -u username --v4      # modern v4 (explicit)
qb install transmission -u username --v3      # legacy 3.00 (Debian 12 / Ubuntu 22 only)

Version availability by distro

The legacy v3 (3.00) build ships only where QuickBox provides compiled 3.00 packages:

On distros where v3 is unavailable, --v3 falls back to installing v4 and prints a notice explaining that the legacy build is not compiled for that distro.

CLI Commands

Dual Packaging Model

Transmission uses different packaging depending on the version series:

• Modern v4 (4.x+) — installed as a single +allmods .deb that bundles all components. Qt6 dependencies are resolved and installed from the compiled-packages manifest alongside the main package. This is the default.
• Legacy v3 (2.x/3.x) — installed as separate subpackages: transmission-daemon, transmission-cli, transmission-common, transmission-gtk, and transmission-qt. All are held at the installed version to prevent accidental upgrades.

This means --v3/--v4 does not just change the version number; it changes the entire packaging structure — which is why switching branch replaces the installation for all users.

Accessing Transmission

After installation, access Transmission at:

https://your-server-ip/transmission/

Login credentials:

• Username: Your QuickBox username
• Password: Your QuickBox password (RPC authentication)

Browser Download Index

In addition to the Transmission Web UI, QuickBox installs a per-user browser file index that lists the contents of your Transmission download directory in a dark-themed fancyindex view. Useful for quickly grabbing a single finished file without loading the torrent client.

https://your-server-ip/username.transmission.downloads

• The listing path matches the Transmission download root, including the downloads/ and watch/ subfolders.
• The index is stitched together per user: if you also have qBittorrent, rTorrent, Deluge, NZBGet, or SABnzbd installed, their completed-download locations are appended into the same username.dlindex.conf so each client gets its own URL. It is one shared browse-index config covering all of that user’s download clients.
• The feature has no service of its own — it is pure nginx. If the page fails to load — returns a 502 or 404, shows blank, or errors — while the rest of the dashboard works normally, the per-user config is broken or missing. Rebuild it with qb fix dlindex -u username (one user) or qb fix dlindex (all users). See the Download Clients overview and the qb fix reference.

Initial Configuration

1. Web Interface Setup

On first access, the web interface is pre-configured:

• RPC authentication: Enabled with your QuickBox credentials
• RPC whitelist: Restricted to 127.0.0.1 for security
• Download directory: /home/username/torrents/transmission/downloads
• Watch directory: /home/username/torrents/transmission/watch

No additional setup required—Transmission is ready to use immediately.

2. Configure Watch Directory (Optional)

Enable automated torrent loading:

1. Navigate to Preferences (gear icon) → Network
2. Verify watch directory is enabled: /home/username/torrents/transmission/watch
3. Drop .torrent files into the watch folder—they’ll be added automatically

3. Connect to *arr Applications (Optional)

If using Sonarr, Radarr, or other *arr applications:

1. In your *arr app, go to Settings → Download Clients → Add (+)
2. Select Transmission from the list
3. Enter connection details:
   • Host: 127.0.0.1
   • Port: Your RPC port (check ~/.config/Transmission/settings.json → rpc-port)
   • URL Path: /transmission/
   • Username: Your QuickBox username
   • Password: Your QuickBox password
4. Test and save

Service Management

Transmission runs as a systemd service for reliability and automatic startup.

systemctl status transmission@username     # Check status
systemctl restart transmission@username    # Restart service
journalctl -u transmission@username -f     # View live logs
systemctl enable transmission@username     # Start on boot
systemctl disable transmission@username    # Prevent auto-start

Troubleshooting

Transmission Won’t Start

journalctl -u transmission@username -f

Check for port conflicts:

grep -i 'rpc-port' ~/.config/Transmission/settings.json
# Default: 15105

Web Interface Not Accessible

Configuration File Corruption

# Stop service
systemctl stop transmission@username
 
# Backup current configuration
cp ~/.config/Transmission/settings.json ~/.config/Transmission/settings.json.backup
 
# Edit or regenerate configuration
nano ~/.config/Transmission/settings.json
 
# Restart service
systemctl start transmission@username

Permission Issues

qb fix permissions -u username
systemctl restart transmission@username

Version Switch Issues

A bare qb update transmission keeps the installed major, so migrating a v3 install to v4 needs the explicit flag. If the in-place migration fails, do a clean reinstall:

# Migrate v3 → v4 in place
qb update transmission -u username --v4
 
# If the migration fails, clean reinstall on v4 (the default)
qb remove transmission -u username
qb install transmission -u username

Best Practices

FAQ

Related Applications

Additional Resources