This feature is included in builds that contain Transmission, an open source BitTorrent client. It allows you to perform downloads/uploads of torrents directly on your router. This means you don't have to leave a LAN device, such as a PC, running just to share Torrent files. To share large files, you will require some form of external storage, such as an external USB drive or a CIFS share.

Enable: Selecting this runs the Transmission process immediately after clicking Save. It then starts the Transmission process at every boot.

Transmission binary path: This specifies where the Transmission binary will be found on the filesystem.

• Internal - Selecting this means FreshTomato's built-in binary will be used.
• Optware - Choosing this makes FreshTomato use an Optware/Entware installation of Transmission.
  FreshTomato will expect to find the binary in the: “opt/bin” directory.
• Custom - Choosing this lets you specify a custom path to the location of the binary.
  

Click here to open Transmission GUI: This will open Transmission's administration graphical interface in a new browser tab.

Keepalive: Enabling this performs “process keepalive” activity, and will restart Transmission if it isn't found to be running.

Check alive every: This value specifies the frequency at which Keepalive is performed.

Delay at startup: The time value defined here (in seconds) will delay the starting of the process at boot time.
This can be useful, for example, when waiting for external storage to be fully ready for use.

Listening port: Here, you specify the port linked to the Transmission process. This will apply to both TCP and UDP.

Downloading directory: This configures the path where you want completed downloads to be stored.

Use incomplete/: If enabled, a subfolder named “incomplete” will store temporary files/folders until the download is completed.

Autoadd .torrents: Enabling this feature, (also known as “blackhole”) will cause Transmission to scan the download folder
for .torrent files and import them automatically.

Enable GUI: This option enables the built-in Transmission GUI. From it, you can administer download/upload activity and configure some program options.

Listening GUI port: This specifies the port on which the Transmission administration page will be reachable.

Authentication required: Choosing this disables anonymous access (strongly suggested) and uses these credentials:

• Username - This specifies your administration username.
• Password - This specifies your administration password.

Allow remote access: If enabled, the Listening port becomes reachable from the WAN.

The Limits section contains settings to define the Transmission's resource limits. The options are pretty much self-explanatory however is more details are needed it is advised to consult the official Transmission documentation.

Download queuing: Is yet another form of limit and controls how many concurrents active Downloads can run simultaneously.
Upload queuing: Same as the option above but applies to Uploads instead.

Find more peers using: Defines on what torrent network type/protocols your Transmission client should participate into. This is not necessarily “all of them”. Some protocols have issues over VPN, others must be disabled when using private peering. You might want to consult the official Transmission documentation and perhaps also the generic Torrent Protocol documentation.

Message level: None(0)/Error(3)/Info(6)/Debug(7) - Defines the highest Transmission loglevel messaged to be captured in the system logs.

Save settings location: Download directory/JFFS/CIFS1/RAM/Custom - to save NVRAM space most of the settings are saved in a file that is read directly by Transmission. Here you can define the preferred filesystem location where this configuration file is to be saved.

Blocklist: Transmission comes with built in blocking capability. You can define here the IP Blocklist of choice (usually Level 1). Essentially these are lists publicly maintained list of “bad IP addresses” like monitoring servers, robot, and much more that undermines the end user privacy. An alternative method to define the single list here is to use the P2Partisan instead where more lists can be defined however a manual script installation is required in the latter case.
Custom Log File Path: Define here the location where you want Transmission to log its activity.
Custom Configuration: Please refer to the official Transmission documentation for additional detail on what it could/should be defined in this field.