Transmission – Port is closed

I don’t often get into 3rd-party software or non-Mac hardware issues, but here’s a little trick I discovered today that could prevent a situation that adversely affects Safari and other network software.

Not so long ago I bought a new router, and everything was working fine. However, when I recently fired up Transmission, I found that not only were my downloads not so fast as I’d normally expect, but that all internet browsing was completely throttled. Basically, Safari would just get stuck half way into loading a page and eventually timeout. Killing Transmission would immediately restore Safari’s connectivity.

Looking in Transmission’s preferences ‘Network’ pane revealed that the port was either closed (red button) or the port could not be checked (yellow button). Now there are a number of reasons this can happen, but since I knew nothing had changed except my router since the last time Transmission was successfully used, I decided to go check out some of the router’s settings.

To do this, quit Transmission if it’s running, then enter your router’s IP address in Safari’s search bar. Typically, this will be something like 192.168.1.1, but if you’re not sure, you can find your router’s IP using my free utility ‘FastTasks‘.

Once you’re in your router’s admin pages, look for Advanced network settings. In my router, I found a bunch of firewall and network protocols (see the first screenshot below). Neither disabling NAT nor UPnP had any effect (those were my first thoughts about the likely culprit), but turning off the ipSec PassThrough option sure did, with the upshot that Safari and Transmission are not only playing nicely together again, but Transmission’s download speeds have markedly improved. 🙂

Here’s the settings I used to get back up and running; see if you can find similar options if you’re experiencing the same problem.

Turning off ‘ipSec PassThrough’ in my Router’s Advanced Settings:

Transmission’s Network Preferences pane:

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disable captive network assistant

If you use coffee shop wifi services or others that require internet login, you’ve probably noticed in both Lion and Mountain Lion that OS X will produce a pop-up Safari window asking you to login. This can be annoying for several reasons:

1. The window floats on top and gets in the way if you’re trying to do something else

2. The window doesn’t keep cookies or allow plug-ins like 1Password, so you have to enter the login details manually every time

3. Sometimes the pop-up window will simply produce an error message that it can’t connect to the network. You either have to dismiss it manually or wait for it to go (it’ll normally auto-close after about 30 seconds)

If you find this behaviour annoying and want to stop it, there’s a very simple solution (and one that’s also easy to undo if you want to reverse it). Here’s what you do.

1. First go to

[Hard Disk] > System > Library > CoreServices > Captive Network Assistant.app

Click on the app once, and hit ‘return’ on your keyboard. This will make the name editable.

2. Hit the ‘left arrow’ key once to move the cursor to the beginning of the name and to unselect the text.

3. Type an ‘X’ (actually any letter will do, but I like ‘X’ so I can easily find the app later at the bottom of the list even if I forgot its exact name).

4. Hit ‘return’ on the keyboard. At this point, OS X will ask you to provide an Admin password as only Admin users are allowed to mess with files in the System directory. Type in your password and hit ‘OK’.

The name should now read ‘XCaptive Network Assistant.app’.

And that’s it! Captive Network Assistant will never run again unless you decide to change its name back to what it was (to do so, just repeat the procedure above and remove the ‘X’). Of course, you can still login to your internet or coffee shop wifi services by opening a normal browser window. The bonus is now your browser can fill the login details from cookies (if enabled) or your password manager.

🙂



featured picture: illuminated jellyfish by weaverglenn