Firefox copy and paste with Apache Guacamole

By: Luke Rawlins Nov 20, 2020 | 3 minutes read
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Tag: Firefox

If you’re not familiar with Apache’s Guacamole project, it is a clientless remote desktop gateway that allows you to access your desktop from any web browser. It’s actually pretty cool software that I’ve been using quite a bit lately.

As a Firefox user, however, one little annoyance has been that direct copy and paste has been a problem. The Guacamole docs have a brief section that explains how to copy and paste using the Guacamole menu bar, but that is combersome and not very user friendly. The Guacamole developers even have a section in the faq that explains the issue. Guacamole has been using the Asynchronous Clipboard API that currently only has limited browser support. Basically it’s only working out of the box on Google Chrome.

This means that by default if you want to use direct copy and paste from your computers clipboard onto the remote computer in Firfox, then you had to use the text box that was built into the Guacamole menu - ugh.

However, there is a solution to this little conundrum in the Firefox advanced preferences.

In the url bar type about:config and press enter. That will take you to the advanced preferences page which will present a warning message, that looks like this:

Firefox advanced menu

Go ahead and click the “Accept the Risk and Continue” button… That is, assuming you trust some random guy on the internet isn’t about to give you bad directions 😨

After you click the Accept button (you did click it right? That last line was just a joke, I wouldn’t steer you wrong). You will be at a mostly blank page with a search bar and yet another caution message. But remember We are not descended from fearful men! And so we press on!

Firefox advanced search

In the search field type “clipboard”. The page should immediately (if not sooner 😒) start filling the page with search results. The setting we are looking for is “dom.events.testing.asyncClipboard”. It will be close to the bottom, and by default its value will be “false”.

Click the toggle button in the right hand column (or double click the setting name) to set the value to “true”.

When it’s changed it should look something like this:

Firefox clipboard settings

You might have to refresh the Guacamole page, or restart the browser - but now you’ll be able to directly copy and paste from your computer into the remote client while skipping the annoying text box.

Feel free to send me a message if this doesn’t work - or if you know a better way.

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