How can I change a user agent string programmatically?

Question

I would like to write a program that changes my user agent string.

How can I do this in Python?

Answer 1

Using Python you can use urllib to download webpages and use the version value to change the user-agent.

There is a very good example on http://wolfprojects.altervista.org/changeua.php

Here is an example copied from that page:

>>> from urllib import FancyURLopener

>>> class MyOpener(FancyURLopener):
...   version = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:1.8.1.11)
 Gecko/20071127 Firefox/2.0.0.11'
>>> myopener = MyOpener()
>>> page = myopener.open('http://www.google.com/search?q=python')
>>> page.read()
[…]Results <b>1</b> - <b>10</b> of about <b>81,800,000</b> for <b>python</b>[…]

Answer 2

I assume you mean a user-agent string in an HTTP request? This is just an HTTP header that gets sent along with your request.

using Python's urllib2:

import urllib2

url = 'http://foo.com/'

# add a header to define a custon User-Agent
headers = { 'User-Agent' : 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)' }

req = urllib2.Request(url, '', headers)
response = urllib2.urlopen(req).read()

Answer 3

In urllib, it's done like this:

import urllib

class AppURLopener(urllib.FancyURLopener):
    version = "MyStrangeUserAgent"

urllib._urlopener = AppURLopener()

and then just use urllib.urlopen normally. In urllib2, use req = urllib2.Request(...) with a parameter of headers=somedict to set all the headers you want (including user agent) in the new request object req that you make, and urllib2.urlopen(req).

Other ways of sending HTTP requests have other ways of specifying headers, of course.

Answer 4

If you want to change the user agent string you send when opening web pages, google around for a Firefox plugin. ;) For example, I found this one. Or you could write a proxy server in Python, which changes all your requests independent of the browser.

My point is, changing the string is going to be the easy part; your first question should be, where do I need to change it? If you already know that (at the browser? proxy server? on the router between you and the web servers you're hitting?), we can probably be more helpful. Or, if you're just doing this inside a script, go with any of the urllib answers. ;)

Answer 5

urllib2 is nice because it's built in, but I tend to use mechanize when I have the choice. It extends a lot of urllib2's functionality (though much of it has been added to python in recent years). Anyhow, if it's what you're using, here's an example from their docs on how you'd change the user-agent string:

import mechanize
cookies = mechanize.CookieJar()
opener = mechanize.build_opener(mechanize.HTTPCookieProcessor(cookies))
opener.addheaders = [("User-agent", "Mozilla/5.0 (compatible; MyProgram/0.1)"),
                     ("From", "[email protected]")]

Best of luck.