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Learn about the various reasons why Firefox makes automatic connections to the Internet and how you can stop it from doing so if you wish.

Some people are concerned about the connections Firefox makes to the Internet, especially when those connections are made for no apparent reason (see Mozilla's [https://www.mozilla.org/privacy/firefox/ Firefox Browser Privacy Notice] for additional information). This article explains various reasons why Firefox may make a connection to the Internet and how you can stop it from doing so, if you wish. __TOC__ = Automatic updates and Security = == Auto-update checking == {warning}'''Warning''': Disabling update checking is not recommended and will leave you open to security vulnerabilities that get fixed in newer versions.{/warning} Firefox occasionally checks to see if any updates are available for itself and for your search engines. To disable these checks: # [[T:optionspreferences]] # Select the {menu Advanced} panel. # Select the {menu Update} tab. # Check '''Never check for updates (not recommended: security risk)''' and uncheck '''Search Engines'''. {for fx38}Close the about:preferences page.{/for} Firefox also checks to see if any updates are available for your add-ons (extensions, themes). To disable this check: #[[T:Open Add-ons|type=Extensions]] #At the top of the tab, click the "Tools for all add-ons" [[Image:Add-on Tools Icon]] menu, uncheck '''Update Add-ons Automatically''' and then select '''Reset All Add-ons to Update Automatically'''. == Blocklist updating == {warning}'''Warning''': Disabling the blocklist is not recommended, as it may result in you using untrustworthy add-ons{for fx37}, revoked certificates{/for} or unstable graphics drivers.{/warning} Firefox may be updating its blocklist, which is used to block malicious extensions, vulnerable plugins{for fx37}, revoked certificates{/for} and graphics drivers known to cause crashes. For more information, see [https://wiki.mozilla.org/Blocklisting Blocklisting] (MozillaWiki), [https://wiki.mozilla.org/Blocklisting/Graphics Blocklisting/Graphics] (MozillaWiki){for fx37}, the [https://blog.mozilla.org/security/2015/03/03/revoking-intermediate-certificates-introducing-onecrl/ Revoking Intermediate Certificates: Introducing OneCRL] blog post{/for} and the article [[Add-ons that cause stability or security issues are put on a blocklist]]. To disable this feature: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref extensions.blocklist.enabled}. # Observe the '''Value''' column of the {pref extensions.blocklist.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. == Anti-phishing list updating == {warning}'''Warning''': Disabling the anti-phishing protection is not recommended, as it will leave you vulnerable to untrustworthy websites that might try to steal your financial information and/or your identity.{/warning} The [[How does built-in Phishing and Malware Protection work?|phishing protection]] list may be updating itself. To turn this off: # [[T:optionspreferences]] # Select the {menu Security} panel. # Uncheck '''Block reported web forgeries'''. == Anti-malware list updating == {warning}'''Warning''': Disabling the anti-malware protection is not recommended, as it will leave you vulnerable to {for fx31}malicious file downloads or {/for}untrustworthy websites that might try to infect you with a virus, trojan or spyware.{/warning} The [[How does built-in Phishing and Malware Protection work?|malware protection]] list may be updating itself. To turn this off: # [[T:optionspreferences]] # Select the {menu Security} panel. # Uncheck '''Block reported attack sites'''. <!-- See https://bugzilla.mozilla.org/show_bug.cgi?id=1090754 --> In addition, when you download an application file, Firefox will verify its signature. If it is signed, Firefox then compares the signature with a list of known safe publishers. For files that are not identified by the lists as “safe” (allowed) or as “malware” (blocked), Firefox asks Google’s Safe Browsing service if the software is safe by sending it some of the download’s metadata. To turn off this part of malware protection: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.safebrowsing.downloads.remote.enabled}. # Observe the '''Value''' Column of the {pref browser.safebrowsing.downloads.remote.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true} then double-click on it to set it to {pref false}. {for fx42} == Tracking protection list updating == The [[Tracking Protection in Private Browsing|tracking protection]] list may be updating itself. To turn this off: # [[T:optionspreferences]] # Select the {menu Privacy} panel. # Uncheck '''Use Tracking Protection in Private Windows'''. {/for} == Secure website certificates == When you visit a secure website (i.e. "https"), Firefox will validate the website's certificate. This may involve communicating with a third-party status provider specified by the certificate over a protocol namend [https://en.wikipedia.org/wiki/Online_Certificate_Status_Protocol OCSP] to confirm that the certificate is still valid. To turn this off: # [[T:optionspreferences]] # Select the {menu Advanced} panel. # Select the {menu Certificates} tab. # Uncheck '''Query OCSP responder servers to confirm the current validity of certificates'''. = Prefetching = == Link prefetching == Firefox will prefetch certain links if any of the websites you are viewing uses the special prefetch-link tag. For more information, please see the [https://developer.mozilla.org/en/Link_prefetching_FAQ Link Prefetching FAQ]. To disable Link prefetching: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref network.prefetch-next}. # Observe the '''Value''' column of the {pref network.prefetch-next} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. == DNS prefetching == In order to reduce latency, Firefox will proactively perform domain name resolution on links that the user may choose to follow as well as URLs for items referenced by elements in a web page. For more information, please see the [http://bitsup.blogspot.co.at/2008/11/dns-prefetching-for-firefox.html DNS Prefetching blog post]. To disable DNS prefetching: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref network.dns.disablePrefetch}. # Observe the '''Value''' column of the {pref network.dns.disablePrefetch} row. #* If it is set to {pref true} then do nothing. #* If it is set to {pref false}, double-click on it to set it to {pref true}. == Speculative pre-connections == To improve the loading speed, Firefox will open predictive connections to sites when the user hovers their mouse over thumbnails on the New Tab Page or the user starts to search in the Search Bar{for fx34}, or in the search field on the Home or the New Tab Page{/for}. In case the user follows through with the action, the page can begin loading faster since some of the work was already started in advance. To disable this feature: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref network.http.speculative-parallel-limit}. # Observe the '''Value''' column of the {pref network.http.speculative-parallel-limit} row. #* If it is set to {pref 0} then do nothing. #* If it is set to a different value, double-click on it to set it to {pref 0}. == Add-on list prefetching == Each time the Add-ons manager is opened, Firefox prefetches a list of add-ons to improve responsiveness of the {menu Get Add-ons} pane. This connection is not made if the add-ons manager is not opened. <!-- See bug https://bugzilla.mozilla.org/show_bug.cgi?id=446301 --> = User-invoked content = == Home page loading == Your home page may be loading. To change your home page to something that doesn't generate connections to the Internet: # [[T:optionspreferences]] # Select the {menu General} panel. # Either set '''When Firefox starts''' to '''Show a blank page''' or set it to '''Show my home page''' and click {button Restore to Default}. {for fx38}Close the about:preferences page.{/for} == Extensions == An extension you have installed may be making a connection to a website that it relies on. For example, a connection to a website to synchronize your bookmarks, a connection to a website 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. {for not fx15}To easily disable all of your extensions please read the [[Troubleshoot Firefox issues using Safe Mode]] article, paying particular attention to the '''Disable all add-ons''' option under the {button Make Changes and Restart} section.{/for} {for fx15} To disable or remove your extensions, see the [[Disable or remove Add-ons]] article.{/for} Firefox also checks to see if any updates are available for your add-ons (extensions, themes). To disable this check: {warning}'''Warning''': Disabling add-on update checking is not recommended and leaves you open to security vulnerabilities that get fixed in newer versions.{/warning} #[[T:Open Add-ons|type=Extensions]] #At the top of the tab, click the "Tools for all add-ons" [[Image:Add-on Tools Icon]] menu, uncheck '''Update Add-ons Automatically''' and then select '''Reset All Add-ons to Update Automatically'''. == Live Bookmarks updating == [[Live Bookmarks - Subscribe to a web page for news and updates|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. == Downloads restarted == When you start Firefox, any interrupted downloads from your previous browsing session may be automatically resumed. # Press {for win}{key Ctrl+J}{/for}{for linux}{key Ctrl+Shift+Y}{/for}{for mac}{key command+J}{/for} to open the [[Where to find and manage downloaded files in Firefox|Downloads window]]. # Ensure nothing is currently being downloaded. == Search plugin icon loading == When you [[Search bar - add, change and manage search engines on Firefox#w_add-a-search-engine|add a custom search plugin]] that doesn't come with an included icon, Firefox might look up the icon at a remote address that is specified in the search plugin once and cache it for future use. == Firefox Sync == If you're using [https://www.mozilla.org/firefox/sync/ Firefox Sync], it will establish regular connections in order to synchronize your data to Mozilla's Sync servers and across your connected devices. In order to choose what data gets synchronized or to disconnect from Sync, see the [[How do I choose what types of information to sync on Firefox?]] article. {for fx34} == Firefox Hello == If you're using the [[Firefox Hello - video and voice conversations online|Firefox Hello]] video and voice chat feature of the browser by signing in with a Firefox Account or starting a conversation, there will be a connection established in order to set up a call, once your conversation partner joins a conversation remotely. Besides signing out from Firefox Hello or deleting a conversation, you can also disable Firefox Hello: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref loop.enabled}. # Observe the '''Value''' column of the {pref loop.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. {/for} = Mozilla content = == Tiles == When you open a new tab in Firefox, you see several tiles that link to different websites. For new users, the [[About Tiles in New Tab |New Tab page]] in Firefox provides recommendations we consider important to our mission ("Directory Tiles"). Directory Tiles will establish a connection to download content and the thumbnails to be shown in the New Tab Page. In order to disable the display of Directory Tiles: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.newtabpage.enhanced}. # Observe the '''Value''' column of the {pref browser.newtabpage.enhanced} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. {for fx40} Disabling the display of such sites won't stop the feature from communicating with Mozilla's servers though. In order to change that: # [[T:aboutconfig]] # In the about:config page, search for the preferences {pref browser.newtabpage.directory.ping} and {pref browser.newtabpage.directory.source}. # Double-click on those preferences and set them to a blank string. {/for} == Snippets == If you use the built-in default homepage about:home, Firefox will show some Mozilla related content around the search box ("Snippets"), which is updated once a day. If you'd like to disable connections to Mozilla's snippets server: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.aboutHomeSnippets.updateUrl}. # Double-click on it and set its value to a blank string. {for fx36} == Geolocation for default search engine == <!--https://bugzilla.mozilla.org/show_bug.cgi?id=1109120--> In order to set the right default search engine for your location, Firefox will perform a geolocation lookup once by contacting Mozilla's servers and store the country-level result locally. This connection happens on the first start of Firefox - in case you want to prohibit that, you will have to preconfigure the browser and set the {pref browser.search.geoip.url} preference to a blank string. {/for} == "What's new" page == After a browser update, Firefox might show an additional tab next to your usual homepage to offer more information on changes or new features included in the update. To disable this page from being shown: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.startup.homepage_override.mstone}. # Double-click on it and set its value to {pref ignore}. == Add-on metadata updating == The Add-ons manager displays information about each add-on you have installed and provides personalized recommendations in the Get Add-ons pane. To keep this data updated, Firefox will request information from the [https://addons.mozilla.org/ Mozilla Add-ons gallery] once a day (for more information, see [https://blog.mozilla.org/addons/how-to-opt-out-of-add-on-metadata-updates/ this blog post]). To disable these updates: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref extensions.getAddons.cache.enabled}. # Observe the '''Value''' column of the {pref extensions.getAddons.cache.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. = Diagnostics = Firefox can submit certain diagnostics data including [[Share telemetry data with Mozilla to help improve Firefox|Telemetry]], [[Firefox Health Report - understand your browser performance|Firefox Health Report]] and [[Mozilla Crash Reporter|Crash Reports]] data to Mozilla to provide information that helps improving the browser. In order to disable the sharing of this data, refer to [[Advanced panel - Accessibility, browsing, network, updates, and other advanced settings in Firefox#w_data-choices-tab_2|Data Choices Tab]]. {for fx37} In addition, Mozilla will ask a small sample of users to rate their experience with Firefox to get a better insight into the sentiment about the browser. For more information about this see [https://wiki.mozilla.org/Advocacy/heartbeat]. The rating feature will establish a connection to Mozilla's servers at startup, which you can turn off like this: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.selfsupport.url}. # Double-click on it and set its value to a blank string. {/for} = Media capabilities = {for fx33} == OpenH264 codec == Firefox will make use of the OpenH264 codec provided by Cisco in order to support the H.264 video codec in WebRTC, a technology allowing for peer-to-peer video communication on the web{for fx34}, like in [[Firefox Hello - video and voice conversations online|Firefox Hello]]{/for}. For more information about this, see the [http://andreasgal.com/2014/10/14/openh264-now-in-firefox/ OpenH264 Now in Firefox] blog post. The OpenH264 codec is not distributed with Firefox but gets downloaded at the first start of Firefox. In case you want to prohibit that, you will have to preconfigure the browser and set the {pref {for not fx37}media.gmp-gmpopenh264.autoupdate{/for}{for fx37}media.gmp-gmpopenh264.enabled{/for}} preference to {pref false}. {/for} <!--once it lands: {for fx39}== DRM content == ...describe the why & how... To disable this feature: # [[T:optionspreferences]] # Select the {menu Content} panel. # Uncheck '''Play DRM content'''. {/for}--> == WebRTC == <!--see https://bugzilla.mozilla.org/show_bug.cgi?id=959893--> [http://en.wikipedia.org/wiki/WebRTC WebRTC] (Web Real-Time Communication) is a technology which provides direct browser-to-browser communication (audio, video, filesharing). As it is drafted and implemented at the moment, WebRTC can lead to your local IP address being exposed to websites even when you are behind a VPN or a NAT router - in the WebRTC API this data would be used to set up a peer-to-peer connection between two local clients. {for not fx42} If you would like to disable WebRTC: # [[T:aboutconfig]] # In the about:config page, search for the preference {pref media.peerconnection.enabled}. # Observe the '''Value''' column of the {pref media.peerconnection.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. {/for} {for fx42}For different methods and granular controls on how to mitigate this issue, see https://wiki.mozilla.org/Media/WebRTC/Privacy. {/for} {for fx36} == Send Video To Device == Firefox contains a "Send Video To Device" feature to send HTML5 video content to a Roku, Chromecast or similar device in the same network. In order to discover and pair with such a device, Firefox will send [http://en.wikipedia.org/wiki/Simple_Service_Discovery_Protocol SSDP] packages (Simple Service Discovery Protocol, multicast address 239.255.255.250, port 1900) to the local network which can trigger a firewall dialog asking you if you want to allow such connections. {for =fx36}A setting to control this behaviour will be available in an upcoming version of Firefox.{/for}{for fx37}To disable this feature:{/for} {for fx37} # [[T:aboutconfig]] # In the about:config page, search for the preference {pref browser.casting.enabled}. # Observe the '''Value''' column of the {pref browser.casting.enabled} row. #* If it is set to {pref false} then do nothing. #* If it is set to {pref true}, double-click on it to set it to {pref false}. {/for} {/for} = Malware = If your computer is infected with a virus, trojan, spyware, or other malicious software, then Firefox's Internet connection may be being piggybacked in order for the malware to communicate with its author or to deliver advertisements, etc. If you suspect this is the case, consider seeking advice from a forum specializing in malware removal. For more information, see [[Troubleshoot Firefox issues caused by malware]]. = Loopback connection = {for linux}{note}Note: This does not apply to Linux systems.{/note}{/for} 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 [https://bugzilla.mozilla.org/show_bug.cgi?id=100154 bug 100154] for more information. <!-- MZ credit --> <br/> <br/> '''''Based on information from [http://kb.mozillazine.org/Connections_established_on_startup_-_Firefox Connections established on startup - Firefox (mozillaZine KB)]'''''