A passionate programmer’s findings in the world of internet.

Lock Firefox Preferences

November 7th, 2006

It is interesting to know that Mozilla provides a mechanism for us to lock any preferences in the option menu. If you would like to play with it, follow these instructions:

  1. Go to Tools > Options...
  2. Change the setting of the preference you want to lock.
    e.g. lock General > Home Page Location to "about:blank".
  3. Open "about:config" to find the key of the preference. Use the filter field to save your time from scrolling up and down.
    e.g. Type in "homepage" and you can find "browser.startup.homepage".
  4. Open a notepad and write in the following lines:
    lockPref("browser.startup.homepage", "about:blank");
  5. Save it as Mozilla.txt and do byte shift with an offset of 13. Use this byte shift service. You will receive a file "mozilla.cfg", which you must save it at the location of firefox.exe.
  6. Add the following line to "C:\Program Files\Mozilla Firefox\greprefs\all.js" file:
    pref("general.config.filename", "mozilla.cfg");

You will find your homepage field in options uneditable after that.

Locking Mozilla Firefox Settings

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10 Responses

earl-ku says:

a kiosk function built in now?

but i prefer the original [x] location, far right, not on every single tab, sometimes switching too fast between tabs will result in closing a few …

i am on FF2.0

EngLee says:

I’m not sure about that. I have not upgraded to 2.0. Too busy to keep myself updated with all the stuffs.

Igor says:

or install Public Fox https://addons.mozilla.org/firefox/3911/

Jahid Ahmed says:

lockPref(“network.proxy.type”, 1);
lockPref(“network.proxy.http”, “”);
lockPref(“network.proxy.http_port”, 8080);
lockPref(“network.proxy.ftp”, “”);
lockPref(“network.proxy.ftp_port”, 8080);
lockPref(“network.proxy.gopher”, “”);
lockPref(“network.proxy.gopher_port”, 8080);
lockPref(“network.proxy.ssl”, “”);
lockPref(“network.proxy.ssl_port”, 8080);
lockPref(“network.proxy.no_proxies_on”, “localhost,”);
lockPref(“network.proxy.socks_version”, 5);
lockPref(“network.proxy.share_proxy_settings”, false);
lockPref(“browser.startup.homepage”, “http://www.blyda.org/|http://www.google.co.uk/”);

wb says:

Dear sir,

i would like some question to ask you about lock config of firefox.

i need to cancel menu (right mouse click of firefox) of “set as desktop background” , can i do ?? if yes, please kindly suggest me 🙂

i need to do some way to protect my users, they always set some ugly picture to desktop. so i think if i can cancel this menu, may be that problem will disappear.

i hope you can help suggestion me 🙂

thank you very much in advance.


EngLee says:

You might want to disable the right click menu?

Here’s the way of doing it: How to disable right click in Firefox

bheem says:

Please tell me how i can lock the home page of the mozilla firefox.

Istanbul says:


How can I lock settings in firefox 3.0.4 and above. The instructions given at the beginning of the page did not work. Any ideas?


Download Free Photos says:

How can I add “no proxy for” ?

vdias says:

thanks for the tip!

Mine looks like this…
lockPref(“browser.shell.checkDefaultBrowser”, false);
lockPref(“app.update.enabled”, false);
lockPref(“network.proxy.type”, 2);
lockpref(“network.proxy.autoconfig_url”, “http://xxxxxxx.com/proxy.pac”);
lockPref(“browser.startup.page”, 1);
lockPref(“browser.startup.homepage”, “http://xxxxxxx.com/”);