Mac/Windows/Linux – Disabling Adobe’s PDF Plugin in Firefox

Back in January 2010 Greg Neagle wrote up a popular article detailing how to set default settings for Firefox. While his article was Mac focused, this technique is able to be used on all platforms. And in using it, you can effectively control a user’s experience with the browser. I previously have been using custom cfg files to disable the annoying update popups users receive, as we use munki to update software and most of our users aren’t administrators anyways. I recently just updated our cfg to disable Adobe’s PDF plugin and thought I’d share how I did it as, if you can believe this, it’s prone to problems. If you don’t already have a custom cfg file in place I recommend reading Greg’s article and following his instructions first. If you’re doing this on Windows or Linux, swap out the file locations mentioned in Greg’s article for the ones posted in the resource section at the end of this article.

Got a custom cfg file? Good. Add the following lines, this has been tested on Firefox 17+:

pref(“browser.preferences.inContent”, true);
pref(“pdfjs.disabled”, false);
pref(‘plugin.disable_full_page_plugin_for_types’, ‘application/pdf’);

The first two lines enable the in-browser PDF viewer Firefox has recently added. The third line forces Firefox to switch back to its default PDF handling action (Use Preview) if any 3rd party PDF plugin is selected on launch. Note that non 3rd party options (i.e. Use Preview, Always Ask, Preview in Firefox, Save File), are able to be chosen and will stick on re-launch. I want to emphasize this point, the above does not stop a user from selecting a 3rd party PDF plugin for their session but will merely reset it if its been done on re-launch.



Windows (may vary on the architecture version installed):

cfg: “C:\Program Files\Mozilla Firefox”

js: “C:\Program Files\Mozilla Firefox\defaults\pref”

Linux (may vary on flavour, installation method, and/or architecture version installed):

cfg: ” /usr/lib/firefox/”

js: “/usr/lib/firefox/defaults/preferences/”


Mac/Windows – Dynamic DNS

I once had to deal with Macs that weren’t properly updating their DNS A and PTR records. The effect of which was that some Macs were getting the wrong hostname and that was causing issues with the Active Directory plug-in. At the time DNS was located on a Windows Domain Controller, and DHCP was coming from a Cisco router. I fixed the problem by handing the DHCP responsibility to the DC and configuring it to update DNS A and PTR records on behalf of the clients. If you’re in a similar situation and can have a Windows server handle DHCP; the options needed to configure this are in the properties on the DHCP scope underneath the DNS tab:

  • Tick “Enable DNS dynamic updates according to the settings below:”
    • Always dynamically update DNS A and PTR records
  • Tick “Discard A and PTR records when lease is deleted”
  • Tick “Dynamically update DNS A and PTR records for DHCP clients that do not request updates (for example, clients running Windows NT 4.0)”

Once this is done you may want to consider purging the current DNS A and PTR records for the DHCP range so that you’re starting fresh.