105

I have the following code in Python:

from selenium.webdriver import Firefox
from contextlib import closing

with closing(Firefox()) as browser:
  browser.get(url)

I would like to print the user-agent HTTP header and possibly change it. Is it possible?

0

5 Answers 5

222
+100

There is no way in Selenium to read the request or response headers. You could do it by instructing your browser to connect through a proxy that records this kind of information.

Setting the User Agent in Firefox

The usual way to change the user agent for Firefox is to set the variable "general.useragent.override" in your Firefox profile. Note that this is independent from Selenium.

You can direct Selenium to use a profile different from the default one, like this:

from selenium import webdriver
profile = webdriver.FirefoxProfile()
profile.set_preference("general.useragent.override", "whatever you want")
driver = webdriver.Firefox(profile)

Setting the User Agent in Chrome

With Chrome, what you want to do is use the user-agent command line option. Again, this is not a Selenium thing. You can invoke Chrome at the command line with chrome --user-agent=foo to set the agent to the value foo.

With Selenium you set it like this:

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
opts = Options()
opts.add_argument("user-agent=whatever you want")

driver = webdriver.Chrome(chrome_options=opts)

Both methods above were tested and found to work. I don't know about other browsers.

Getting the User Agent

Selenium does not have methods to query the user agent from an instance of WebDriver. Even in the case of Firefox, you cannot discover the default user agent by checking what general.useragent.override would be if not set to a custom value. (This setting does not exist before it is set to some value.)

Once the browser is started, however, you can get the user agent by executing:

agent = driver.execute_script("return navigator.userAgent")

The agent variable will contain the user agent.

11
  • Note that I have from selenium.webdriver import Firefox. I'm trying to figure out, how to set the profile for Firefox, I imported from selenium.webdriver.
    – xralf
    Apr 30, 2015 at 11:56
  • 1
    user-agent is not request or response header, but it is general header.
    – xralf
    Apr 30, 2015 at 11:56
  • 2
    I deal with Firefox in my answer in the first code snippet. Also, User-Agent absolutely is a request header. See section 14.43: "The User-Agent request-header field contains information about the user agent originating the request." (Emphasis mine.)
    – Louis
    Apr 30, 2015 at 11:59
  • OK, I combined it with my code. So, for setting user-agent is there a set_preference method. Is there something like get_preference as well, to know what it was before?
    – xralf
    Apr 30, 2015 at 12:22
  • You're right, it is a request-header field. In the book HTTP essentials (page 56) is mistake.
    – xralf
    Apr 30, 2015 at 12:23
24

This is a short solution to change the request UserAgent on the fly.

Change UserAgent of a request with Chrome

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

driver = webdriver.Chrome(driver_path)
driver.execute_cdp_cmd('Network.setUserAgentOverride', {"userAgent":"python 2.7", "platform":"Windows"})
driver.get('http://amiunique.org')

then return your useragent:

agent = driver.execute_script("return navigator.userAgent")

Some sources

The source code of webdriver.py from SeleniumHQ (https://github.com/SeleniumHQ/selenium/blob/11c25d75bd7ed22e6172d6a2a795a1d195fb0875/py/selenium/webdriver/chrome/webdriver.py) extends its functionalities through the Chrome Devtools Protocol

def execute_cdp_cmd(self, cmd, cmd_args):
        """
        Execute Chrome Devtools Protocol command and get returned result

We can use the Chrome Devtools Protocol Viewer to list more extended functionalities (https://chromedevtools.github.io/devtools-protocol/tot/Network#method-setUserAgentOverride) as well as the parameters type to use.

1
  • This would be useful when I want to change the user agent on every request, but not the whole driver session
    – migrant
    Jan 13, 2021 at 13:50
19

To build on Louis's helpful answer...

Setting the User Agent in PhantomJS

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
...
caps = DesiredCapabilities.PHANTOMJS
caps["phantomjs.page.settings.userAgent"] = "whatever you want"
driver = webdriver.PhantomJS(desired_capabilities=caps)

The only minor issue is that, unlike for Firefox and Chrome, this does not return your custom setting:

driver.execute_script("return navigator.userAgent")

So, if anyone figures out how to do that in PhantomJS, please edit my answer or add a comment below! Cheers.

1
  • I do it but this massage is published when I run it: http.client.RemoteDisconnected: Remote end closed connection without response Sep 30, 2018 at 10:56
11

Firefox Profile is deprecated, you have to use it in Firefox options like this:

opts = FirefoxOptions()
opts.add_argument("--headless")
opts.add_argument("--width=800")
opts.add_argument("--height=600")
opts.set_preference("general.useragent.override", "userAgent=Mozilla/5.0 
(iPhone; CPU iPhone OS 15_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like 
Gecko) CriOS/101.0.4951.44 Mobile/15E148 Safari/604.1")
0

To build on JJC's helpful answer that builds on Louis's helpful answer...

With PhantomJS 2.1.1-windows this line works:

driver.execute_script("return navigator.userAgent")

If it doesn't work, you can still get the user agent via the log (to build on Mma's answer):

from selenium import webdriver
import json
from fake_useragent import UserAgent

dcap = dict(DesiredCapabilities.PHANTOMJS)
dcap["phantomjs.page.settings.userAgent"] = (UserAgent().random)
driver = webdriver.PhantomJS(executable_path=r"your_path", desired_capabilities=dcap)
har = json.loads(driver.get_log('har')[0]['message']) # get the log
print('user agent: ', har['log']['entries'][0]['request']['headers'][1]['value'])
4
  • Hi, Could you tell me what's your mean from "your_path" in this part: driver = webdriver.PhantomJS(executable_path=r"your_path", desired_capabilities=dcap) Sep 30, 2018 at 9:59
  • I guess you want to say address of "phantomjs.exe" in "bin file". Sep 30, 2018 at 10:01
  • I do it but, this massage will be published for me: http.client.RemoteDisconnected: Remote end closed connection without response Sep 30, 2018 at 10:53
  • I do it but I can't see any change in browser is "under remote control" mood. Can you analyze it? Sep 30, 2018 at 11:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.