How to disable Firefox captive portal test connection on startup

Mozilla’s Firefox web browser tests at startup whether the network connection being used requires a login; this is common when a device is connected to a public hotspot, for example when using a hotel’s wireless connection.

While that’s useful in some cases, it’s not something that many Firefox installations require. If you use Firefox only at home, you do not need to verify. It reduces the automatic connections made by the browser and can also speed up the startup a bit.

Firefox tries to connect to http://detectportal.firefox.com/success.txt during the test to see if it can connect to the address. The same address is also used to test whether the active network connection supports IPv6.

Note: You may need to undo your changes if you experience connectivity issues; this shouldn’t be the case, but it’s easy to undo if something goes wrong.

Disable Firefox network connectivity tests

1. Load about:config into the Firefox address bar to get started.
2. Confirm the message “Accept the risk and continue” that is displayed. You may also want to uncheck “Warn me when I try to access these preferences” to skip the prompt next time.
3. Find preference network.cautive-portal-service.enabled using the search field at the top.
4. Set the preference to FALSE by clicking the toggle icon on the right. To undo the change, repeat the action so that the value of the preference is TRUE.
5. Find preference network.connectivity-service.enabled using the same method described above.
6. Set the preference to FALSE clicking the toggle icon. To undo the change, repeat the action so that the value of the preference is set back to TRUE.

The network.captive-portal-service.enabled preference checks if the network connection requires authentication. Firefox users who travel a lot and those who connect to networks that require authentication may want to keep the default preference value of TRUE. Everyone else can set it to FALSE without any usability or connectivity issues.

The network.connectivity-service.enabled preference determines the capabilities of the network connection connecting to the same address as network.captive-portal-service.enabled.

The Tor project disabled the functionality in its browser, with no issues reported since the change. The development team noted that Firefox makes this connection every time the network state changes:

NetworkConnectivityService polls http://detectportal.firefox.com/success.txt?ipv4 and http://detectportal.firefox.com/success.txt?ipv6 every time the network status changes (event network:link-status- changed). We should probably disable this unless it is necessary for browser functionality.

closing words

Most Firefox users don’t need both preferences when using the browser. Some users may want to do this for privacy, others to reduce the number of connections the browser makes.

Now you: do you monitor the automatic connections of your browser?

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