How to stop Firefox from making automatic connections | Firefox Help

How to stop Firefox from making automatic connections | Firefox Help
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Firefox
Firefox
7/24/25
51%
of users voted this helpful
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
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.
Table of Contents
Automatic updates and Security
1.1
Auto-update checking
1.2
Blocklist updating
1.3
Anti-phishing and malware protection lists updating
1.4
Tracking protection list updating
1.5
Secure website certificates
1.6
Login breach information
Prefetching
2.1
Link prefetching
2.2
DNS prefetching
2.3
Speculative pre-connections
2.4
Add-on list prefetching
User-invoked content
3.1
Homepage loading
3.2
Extensions
3.3
Downloads restarted
3.4
Search plugin icon loading
3.5
Firefox Sync
Mozilla content
4.1
Contextual feature recommendations and other notifications
4.2
Experiments or studies
4.3
Geolocation for default search engine
4.4
“What's new” page
4.5
Add-on metadata updating
Diagnostics
Media capabilities
6.1
OpenH264 codec
6.2
DRM content
6.3
WebRTC
Network Detection
Malware
Loopback connection
Automatic updates and Security
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 and for your search engines. The ability to disable Firefox update checking was removed years ago. Advanced users and IT administrators can use a policy to disable Firefox update checks. See
Manage Firefox updates
Firefox also checks to see if any updates are available for your
add-ons (extensions and themes)
extensions and themes
. To disable this check:
Warning:
Disabling add-on update checking is not recommended and leaves you open to security vulnerabilities that get fixed in newer versions.
Click the menu button
, click
Add-ons and themes
Extensions and themes
and select
Extensions
At the top of the tab, click the
Tools for all add-ons
menu, uncheck
Update Add-ons Automatically
and then select
Reset All Add-ons to Update Manually
Blocklist updating
Warning:
Disabling the blocklist is not recommended, as it may result in you using untrustworthy add-ons, revoked certificates or unstable graphics drivers.
Firefox may be updating its blocklist, which is used to block malicious extensions, vulnerable plugins, revoked certificates and graphics drivers known to cause crashes. For more information, see
Add-ons Blocking Process
(Firefox Extension Workshop),
Blocklisting/Graphics
(Mozilla Wiki),
Revoking Intermediate Certificates: Introducing OneCRL
(Mozilla Security Blog) and the
Why does Mozilla disable some add-ons from running in Firefox?
article. To disable this feature:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
extensions.blocklist.enabled
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 it to set it to
false
Anti-phishing and malware protection lists updating
Warning:
Disabling phishing and malware protection is not recommended, as it will leave you vulnerable to malicious or unwanted downloads and to untrustworthy websites that try to steal your financial information and/or your identity.
Phishing, unwanted software and malware protection
lists may be updating. To turn this off:
In the Menu bar at the top of the screen, click
Firefox
and select
Settings
(or
Preferences
, in some cases).
Click the menu button
and select
Settings
Select the
Privacy & Security
panel.
Uncheck
Block dangerous and deceptive content
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:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
browser.safebrowsing.downloads.remote.enabled
Observe the
Value
column of the
browser.safebrowsing.downloads.remote.enabled
row.
If it is set to
false
then do nothing.
If it is set to
true
then double-click it to set it to
false
Tracking protection list updating
The
tracking protection
list may be updating itself. To turn this off:
In the Menu bar at the top of the screen, click
Firefox
and select
Settings
(or
Preferences
, in some cases).
Click the menu button
and select
Settings
Select the
Privacy & Security
panel.
Under Enhanced Tracking Protection, choose the
Custom
setting.
Uncheck
Tracking content
Secure website certificates
When you visit a secure website (“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 named
OCSP
to confirm that the certificate is still valid. To turn this off:
In the Menu bar at the top of the screen, click
Firefox
and select
Settings
(or
Preferences
, in some cases).
Click the menu button
and select
Settings
Select the
Privacy & Security
panel.
In the
Security
section under
Certificates
, uncheck
Query OCSP responder servers to confirm the current validity of certificates
Login breach information
Firefox Monitor
warns you if your online accounts were involved in a known data breach. For more information, see
Firefox Password Manager - Alerts for breached websites
To get the latest login breach information and more, Firefox connects to
firefox.settings.services.mozilla.com
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
Link Prefetching FAQ
. To disable Link prefetching:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
network.prefetch-next
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 it to set it to
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
DNS Prefetching blog post
. To disable DNS prefetching:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
network.dns.disablePrefetch
Observe the
Value
column of the
network.dns.disablePrefetch
row.
If it is set to
true
then do nothing.
If it is set to
false
, double-click it to set it to
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, or in the search field on the Home or the New Tab page. 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:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
network.http.speculative-parallel-limit
Observe the
Value
column of the
network.http.speculative-parallel-limit
row.
If it is set to
then do nothing.
If it is set to a different value, double-click it to set it to
Add-on list prefetching
Each time the
Add-ons manager
is opened, Firefox prefetches a list of add-ons to improve responsiveness of the
Recommendations
panel. This connection is not made if the add-ons manager is not opened.
User-invoked content
Homepage loading
To
set your homepage
to something that doesn't generate connections to the Internet:
In the Menu bar at the top of the screen, click
Firefox
and select
Settings
(or
Preferences
, in some cases).
Click the menu button
and select
Settings
Select the
panel.
Under
New Windows and Tabs
in the drop-down menu after
Homepage and new windows
, select
Blank Page
in the drop-down menu after
New tabs
, select
Blank Page
Close the
about:preferences
page.
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, the FasterFox extension has an option to prefetch all links. To disable or remove your extensions, see
Disable or remove Add-ons
Downloads restarted
When you start Firefox, any interrupted downloads from your previous browsing session may be automatically resumed.
Press
Ctrl
Ctrl
Shift
Command
to open the
Downloads window
Ensure nothing is currently being downloaded.
Search plugin icon loading
When you
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
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
How do I choose what information to sync on Firefox?
Mozilla content
Note:
The
Configuration Editor for Firefox
article describes in detail how to use
about:config
to modify preferences.
Contextual feature recommendations and other notifications
Firefox may make feature recommendations specific to a type of website you're on or relevant to a current task. You can disable connections by opting out of all Firefox recommendations via Firefox settings. See
Recommendations from Firefox
for details.
Experiments or studies
To disable new feature experiments, set
messaging-system.rsexperimentloader.enabled
to
false
To disable the running of experiments, set
app.shield.optoutstudies.enabled
to
false
. This is not necessary if
app.normandy.enable
is also set to
false
To disable studies, feature rollouts and emergency hotfixes related to Normandy, set
app.normandy.enabled
to
false
Geolocation for default search engine
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
browser.search.geoip.url
preference to a blank string.
“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:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
browser.startup.homepage_override.mstone
Double-click it and set its value to
ignore
Add-on metadata updating
The Add-ons manager displays information about each add-on you have installed and provides personalized recommendations in the
Recommendations
panel. To keep this data updated, Firefox will request information from the
Mozilla Add-ons gallery
once a day (for more information, see
this blog post
). To disable these updates:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
extensions.getAddons.cache.enabled
Observe the
Value
column of the
extensions.getAddons.cache.enabled
row.
If it is set to
false
then do nothing.
If it is set to
true
, double-click it to set it to
false
Diagnostics
Firefox can submit certain diagnostics data, including
Telemetry
and
Crash Reports
data to Mozilla, to provide information that helps improve the browser. You can disable sharing of this data in Firefox Settings
. To disable the sharing of this data:
In the Menu bar at the top of the screen, click
Firefox
and select
Settings
(or
Preferences
, in some cases).
Click the menu button
and select
Settings
Select the
Privacy & Security
panel.
Uncheck the boxes under the section
Firefox Data Collection and Use
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
Firefox/Shield/Heartbeat
(MozillaWiki). The rating feature will establish a connection to Mozilla's servers at startup, which you can turn off like this:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
Find the preference
app.normandy.enabled
Set the preference value to
false
by double-clicking it.
Media capabilities
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 more information about this, see the
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
media.gmp-gmpopenh264.enabled
preference to
false
DRM content
To disable this feature, see
Watch DRM content on Firefox
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 different methods and granular controls on how to mitigate this issue, see
Media/WebRTC/Privacy Media/WebRTC/Privacy Media/WebRTC/Privacy
Mozilla Wiki page.
Network Detection
Firefox's captive portal feature tests whether your network connection requires logging in, for example, on a public Wi-Fi hotspot, by regularly connecting to
. Firefox will also make connections to this URL to check if your current network supports IPv6.
To disable this feature:
Type
about:config
in the
address bar
and press
Enter
Return
A warning page may appear. Click
Accept the Risk and Continue
to go to the
about:config
page.
In the
about:config
page, search for the preference
network.captive-portal-service.enabled
(for example, you can type
portal
in the search box above the list and pause while the list is filtered).
Observe the
Value
column of the
network.captive-portal-service.enabled
row.
If it is set to
false
then do nothing.
If it is set to
true
, double-click it to set it to
false
In the
about:config
page, search for the preference
network.connectivity-service.enabled
(for example, you can type
connectivity
in the search box above the list and pause while the list is filtered).
Observe the
Value
column of the
network.connectivity-service.enabled
row.
If it is set to
false
then do nothing.
If it is set to
true
, double-click it to set it to
false
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
Note:
This does not apply to Linux systems.
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.
Based on information from
Connections established on startup - Firefox (mozillaZine KB)
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