Firefox makes unrequested connections

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Some people are particularly concerned about the connections Firefox makes to the internet, especially when such connections are made with no apparent cause. This article will explain the various reasons why Firefox may legitimately make a connection to the internet, and how you can stop it from doing so if you so desire.

Table Of Contents

Loopback connection

A loopback connection (to IP address 127.0.0.1) can be made by Firefox on non-Unix machines. In this case the browser is communicating with itself as expected, and it is not recommended that this communication be blocked. See bug 100154 for more information.

Live Bookmarks updating

Live Bookmarks automatically reload themselves on a regular basis, and in doing so will make a connection to the internet. Deleting all your Live Bookmarks will stop these connections from being made.

Auto-update checking

Warning: Disabling update checking is not recommended and will leave you open to security vulnerabilities that get fixed in newer versions.

Firefox occasionally checks to see if any updates are available for itself, for your add-ons (extensions, themes, etc), and for your search engines. To disable these checks:

  1. At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
  2. Select the Advanced icon.
  3. Select the Update tab.
  4. Uncheck Firefox, Installed Add-ons, and Search Engines.

Home page loading

Your home page may be loading. To change your home page to something that doesn't generate connections to the internet:

  1. At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
  2. Select the Main icon.
  3. Set When Firefox starts to Show a blank page.

Anti-phishing list updating

Warning: Disabling the anti-phishing protection is not recommended, as it will leave you vulnerable to untrustworthy web-sites that might try to steal your financial information and/or your identity.

The phishing protection list may be updating itself. To turn this off:

  1. At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
  2. Select the Security icon.
  3. Uncheck Tell me if the site I'm visiting is a suspected forgery.
Firefox 3:

Anti-malware list updating

Warning: Disabling the anti-malware protection is not recommended, as it will leave you vulnerable to untrustworthy web-sites that might try to infect you with a virus, trojan or spyware.

The malware protection list may be updating itself. To turn this off:

  1. At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
  2. Select the Security icon.
  3. Uncheck Tell me if the site I'm visiting is a suspected attack site.

Add-on list prefetching

Each time the Add-ons window is opened, Firefox prefetches a list of add-ons to improve responsiveness of the Get Add-ons pane. This connection is not made if the add-ons manager is not opened.

Firefox will prefetch certain links if any of the web sites you are viewing uses the special prefetch-link tag. For more information, please see the Link Prefetching FAQ. To disable prefetching:

  1. In the Location bar, type about:config, and press EnterReturn.
    • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page.
  2. In the about:config page, search for the preference network.prefetch-next.
  3. Observe the Value column of the network.prefetch-next row.
    • If it is set to false then do nothing.
    • If it is set to true, double-click on it to set it to false.

Extension blocklist updating

Warning: Disabling blocklist updating is not recommended and may result in you using extensions known to be untrustworthy.

Firefox may be updating its extension blocklist. To disable this:

  1. In the Location bar, type about:config, and press EnterReturn.
    • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page.
  2. In the about:config page, search for the preference extensions.blocklist.enabled.
  3. Observe the Value column of the extensions.blocklist.enabled row.
    • If it is set to false then do nothing.
    • If it is set to true, double-click on it to set it to false.

Live Title updating

If you have any Live Title bookmarks, they may be updating themselves. Deleting all your Live Title bookmarks will stop these connections from being made. For more information, please see the Microsummaries wiki page.

Extensions

An extension you have installed may be making a connection to a web site that it relies on. For example, a connection to a web site to synchronize your bookmarks, a connection to a web site to update a list of sites to block, etc. Or it is possible an extension could be changing the expected behavior of Firefox in other ways. For example, FasterFox extension has an option to prefetch all links.

To easily disable all of your extensions please read the Safe Mode article, paying particular attention to the Disable all add-ons option under the Make Changes and Restart section.

Firefox 3:

Downloads restarted

When you start Firefox, any interrupted downloads from your previous browsing session may be automatically resumed.

  1. From the menu bar at the top of the Firefox window, select the Tools menu and then select the Downloads menu item.
  2. Ensure nothing is currently being downloaded

Windows:

Infected with malware

If your machine is infected with a virus, trojan, or spyware, then Firefox's internet connection may be being piggybacked in order for the malware to communicate with its author or to deliver adverts onto your machine, etc. If you suspect this is the case, consider seeking specialized advice from one of these malware support sites:

Please be aware that Mozilla is not responsible for the content of third-party web sites.




Based on information from Connections established on startup - Firefox (mozillaZine KB)


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Page last modified on Sunday 31 of August, 2008 14:50:09 PST.
Contributors to this page: Chris_Ilias , Cww , Bo , jscher2000 , AliceWyman , admin , np and stevee .
- This is a support/troubleshooting article -