Firefox Browser

Log in to CLASSE web pages with Kerberos ticket (preset on CLASSE-managed Linux and Windows machines)

Please see ClasseAuthentication for more information.

Please follow these steps to configure Firefox to support HTTP Negotiate authentication. By default all managed CLASSE systems should already have this configuration set.
  1. In the address bar of Firefox, type about:config to display the list of current configuration options.
  2. In the Filter field, type negotiate to restrict the list of options.
  3. Double-click the network.negotiate-auth.trusted-uris entry to display the "Enter string value" dialog box.
    • Enter classe.cornell.edu
  4. Double-click the network.negotiate-auth.delegation-uris entry to display the "Enter string value" dialog box.
    • Enter classe.cornell.edu

Profile Size

In some cases, firefox profiles can become very large. A good way to limit the size of your firefox profile is to limit the cache size to 24MB as follows:
  • browse to about:config
  • search for browser.cache.disk.capacity
  • change browser.cache.disk.capacity to 24000

Clearing Cache

To clear the cache for a specific site, hold down the shift key while clicking on the Reload button in your browser.

Alternatively, in some cases you may want to clear your entire cache and recent browsing history. This can also be used to decrease the size of your firefox profile.

  • click on History and choose Clear Recent History
  • set Time range to clear: (for example, to Everything )
  • check Cache (and any others you'd like)
  • click on Clear Now

Profile Manager

Start the Firefox ProfileManager by typing the command.

firefox -ProfileManager

You can then start firefox with a specific profile by typing either

firefox -P profile


firefox -SelectProfile.

Exporting Bookmarks

Although Firefox automatically creates daily backups of your bookmarks, you can also manually export your bookmarks -- see links below for instructions. We strongly recommend storing your exported bookmarks on a centrally backed-up CLASSE filesystem (a.k.a. samba).

Restoring Bookmarks

Firefox automatically makes backups of bookmarks, which can be restored by following https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them#w_restoring-from-backups

User Install of Firefox (Windows)

  • Download the latest version of Firefox
    • You can download Firefox from Firefox Download and run the new Firefox installer file.
    • It might say it is upgrading Firefox, but will actually do a user install to your profile.
    • There will be a Firefox icon on your desktop when the install is complete.

  • If you have a backup of your bookmarks from a different computer or previous install: Restore your bookmarks in the new user-installed Firefox:
    1. Click the Library button on your toolbar.
    2. Click Bookmarks to expand the menu, then click the Manage Bookmarks at the bottom. This will open a new window named "Library".
    3. From the toolbar on the Library window, click the Import and Backup button, choose Restore... from the drop-down menu and select Choose File...
    4. Navigate to the folder where you saved your bookmarks in the steps above and select the "bookmarks-date.json" file. Click Open
    5. A popup window will appear to confirm that you want to replace your current bookmarks with the backup. Click OK.
For more information you can go to Mozilla Support-Restore Firefox Bookmarks
  • By default, automatic updates are enabled. This setting must not be changed.

Disable PDF Browser Plugin in Firefox

  • Under Linux and OSX with Firefox v38 and the "Menu Bar" enabled
    1. Click on "Edit" and choose "Preferences" (proceed with step 2 below)
  • Under Windows with Firefox v38 and the "Menu Bar" enabled:
    1. Click on "Tools" and select "Options"
    2. From the "Applications" tab, search for PDF. If it's there, set to "Save File".
    3. Exit completely from Firefox
  • When you run Firefox again, pdf's will be downloaded to disk.
    • You can then view them on Linux using evince (or selecting "Use Document Viewer" in the GUI),
    • On Windows use PDF-Xchange, etc.

Allow pop-ups for certain websites


Disable Hardware Acceleration

New releases of Firefox enable hardware acceleration. If you experience strange artifacts, flashing, etc., we highly recommend disabling hardware acceleration.
  • Under Linux and OSX with Firefox v38 and the "Menu Bar" enabled
    1. Click on "Edit", and select "Preferences" (proceed with step 2 below)
  • Under Windows with Firefox v38 and the "Menu Bar" enabled:
    1. Click on "Tools" and select "Options"
    2. Click on the "Advanced" icon
    3. Click on the "General" tab
    4. Under "Browsing", un-check "Use hardware acceleration when available"

lock file (Linux)

Firefox uses lock files in your profile directory to make sure that profile is only used by one firefox process at a time. One of these files is named ".parentlock," and the file named "lock" is a link that contains the IP Address and process id that firefox thinks it is running on. For example, the following means that firefox is running on using the process id of 21557.
[dab66@lnx246 ~]% ls -lrt ~/.mozilla/firefox/426glbem.default/lock
lrwxrwxrwx 1 dab66 cmpgrp 20 Aug 13 11:25 /home/dab66/.mozilla/firefox/426glbem.default/lock ->

[dab66@lnx246 ~]% ps -p 21557
  PID TTY          TIME CMD
21557 ?        00:00:45 firefox

If Firefox dies unexpectedly and is not able to remove the lock file, it will refuse to start. Once you ensure that firefox really isn't running on the computer indicated by the lock file, you can manually delete the lock and .parentlock files to allow a new firefox process to start.

Quota (Linux)

Firefox automatically creates a sqlite database and cache files in your home directory. In rare cases these can grow very large and unexpectedly fill your quota on our unix home disks.

If this becomes an issue for you even with the above cache settings, one option is to move your ~/.mozilla/firefox and ~/.cache/mozilla/firefox directories from your home directory to a separate NFS filesystem. This can be accomplished as in this example. Of course the NFS directory will be different for most users. Please discuss an appropriate location with your supervisor, and contact the computer group if needed.
  1. quit firefox, and use ps aux |grep firefox to make sure no processes are still running.
  2. mv ~/.mozilla/firefox /nfs/some/directory/
  3. ln -s /nfs/some/directory/firefox ~/.mozilla/
  4. restart firefox.

Please note that this may make firefox appear to run slower when the nfs server is first mounted or is heavily loaded.

Profile Unavailable (Linux)

Thunderbird and Firefox can refuse to launch, claiming falsely that your profile is not available when it can be their directories in your home directories .cache directory. Fix that, and all will work.
Topic revision: r25 - 11 Mar 2022, JamesPulver
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