title: How to set proxy AUTHENTICATION username:password using Python/Selenium
body: <p>I am using:</p>
  
  <ul>
  <li>Selenium 4</li>
  <li>python 3.7</li>
  <li>Firefox webdriver</li>
  </ul>
  
  <p>I need to verify the username and password for my current project. I've been working day and night for days and I can't solve this problem. I've found a few extension on the internet, but it's from '13 year and I guess that's why it doesn't work. You can also see other methods I've tried below.</p>
  
  <p>But doesn't work, because Proxy Authentication is not working anymore due to the Selenium bug..</p>
  
  <pre><code>alert_popup = browser.switch_to_alert()
      alert_popup.send_keys(
          "{username}{tab}{password}{tab}".format(
              username=proxy_username, tab=Keys.TAB, password=proxy_password
      )
  )
  alert_popup.accept()
  </code></pre>
  
  <p>I wanted to create a profile and save the proxy information manually and start selenium with that profile. However, firefox does not allow user name and password to be entered manually.</p>