Automation tool for Firefox that can manipulate User-Agent or Referrer?

I need to automate some processes in Firefox via Chickenfoot, Greasemonkey, iMacros or any other automation tool. Is any of them allows to change the browser's User-Agent or Referer/Referrer fields?

Thanks a lot!

EDIT: I see people mention to use one of the many Firefox plugins to control Referrer. But the problem is that most of the add开发者_JS百科ons allow to set the referrer manually in the beginning of the session. I need the referrer to be changing many time during the automation process.

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Greasemonkey will let you specify a user agent when you use the GM_xmlhttpRequest function, but it won't let you change referrer.

Some Firefox extensions that will probably do what you want:

1. User Agent Switcher
2. RefControl

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Depending on your needs, you might be able to leverage User Agent Switcher, which is an awesome extension (add on) for doing this:

https://addons.mozilla.org/en-US/firefox/addon/user-agent-switcher/