Transmission is a great tool for downloading torrents on your Mac at home--y'know, all those Linux distros--but if you’re in a hurry you might not have the time to sit and monitor the download.

Enter iControlBits for iOS. This $1.99 application from the iTunes App Store will let you monitor and control your Transmission downloads from anywhere you have a wireless connection. There has been a Transmission-included web server for a while now that will let you control your torrent downloads via a browser-based webpage, but iControlBits stepped this up a notch by creating a native application that you can use on your iPhone or iPod touch.

What You’ll Need

>> iControlBits ($1.99 from iTunes App Store)
>> iPhone or iPod touch
>> Mac Running Transmission
>> Router with Port Forwarding Capabilities (we’ll use an AirPort Extreme)

Step 1: Give Your Mac a Static IP Address (... and we’re not talking cling wrap)

The Mac you’re going to be using needs to have a static IP address. Typically, your Mac will have a dynamically allocated IP address. Dynamic addresses will change periodically (usually when you restart your computer), while static addresses will remain the same.

To change your Mac’s IP address, navigate to System Preferences > Network. Click on your connection method in the right-hand corner (i.e. if you’re connected by Wi-Fi, then select AirPort). Once you have selected your connection method, click the “Advanced...” button in the lower right-hand corner of the System Preferences pane.

This will open a new dialog. From here, click the TCP/IP tab, then select “Using DHCP with manual address” from the “Configure IPv4” drop-down menu.

You will now need to enter a static address for your Mac in the IPv4 Address field. This number will typically begin with the first 3 segments of numbers from your Router field, then will have a new number for the last digit. So, if you’re Router address is listed as, say, 192.168.1.1, an address you could type in would be 192.168.1.15. You want to avoid typing in an address that another system is currently using as this could cause network connectivity problems on your Mac.

When you’re done typing in the static address, write it down for later reference, then click the OK button. Back in the Network preferences pane, click Apply to save the changes.

Step 2: Configure Port Forwarding On Your Router

Next, we need to configure port forwarding on your network router. iControlBits and Transmission by default uses port 9091. Port forwarding will tell the router to access your Mac when this port is connected to on your home Internet connection, allowing you to directly send and retrieve data from the built-in Transmission web service on your Mac.

We’ll be using an AirPort Extreme to configure the port forwarding, but you can do this on pretty much any router that you may have. If you’re using a different router, please consult your documentation for more information about port forwarding.

When you’re ready to continue, open AirPort Utility on your Mac. Once there, click on your AirPort router in the sidebar, then click the Manual Setup button.

Once you have entered manual setup mode, navigate to Internet > NAT > Configure Port Mappings. Once here, click the plus (+) button to add a new port forwarding service.

A Port Mapping Setup Assistant will drop-down, letting you configure several pieces of information. Leave the Service drop-down menu at the default selection (“Choose a service”), then type in “9091” for the Public UDP Port, Public TCP Port, Private UDP Port, and Private TCP Port. Then, type in your Mac’s static address (that you just configured) into the Private IP Address field.

This will tell the router that any traffic coming into your router on port 9091 should be forwarded to your Mac using the same port.

When you’re done, click the Continue button. From this screen, give your port mapping a description, then click Done. When you’re done configuring your router, click the Update button. After a few minutes your router will restart, saving your settings.

Step 3: Configure Transmission on Your Mac

Now we need to do a little tweaking to Transmission on your Mac. Navigate to Transmission > Preferences, then click on the Remote tab.

From this screen, click the checkbox to Enable remote access. Then, if you want to protect Transmission against unauthenticated requests, check the Require authentication checkbox and specify a username and password. Next, ensure the Listening Port is 9091 (the default).

When you are finished configuring Transmission, you can close the preferences, leaving Transmission opened.

Step 4: Configure iControlBits on iOS

We finally get to the rewarding part: configuring iControlBits and connecting to our Mac to control Transmission remotely.

Start by opening iControlBits, then select the plus (+) button in the top right-hand corner of the screen to add a new server.

A new Server settings screen will open up, allowing you to enter your configuration.

First, you’ll need to provide a Display name. This name can be anything you want to enter. Next, enter your Hostname or public internet IP Address. You can get this IP address by visiting a site like IP Chicken from your Mac. Ensure 9091 is entered for the Port number, then enter a username or password (if you configured one in Transmission’s preferences above). Finally, tap on the Save button in the top right-hand corner of the screen.

When you save your server settings, you will be returned to the server list in iControlBits. Tap on the server that we just created to connect to it. Assuming you completed all the steps above, you should now be able to see and control any torrents that you currently have downloading, completed, or stopped.

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