urllib2 can not (at least up to python 2.3 and 2.4) send files using POST and multipart/form-data encoding.

urllib2_file Github link

import urllib2_file
import urllib2

data = {'name': 'value',
        'file':  open('/etc/services')
       }
urllib2.urlopen('http://site.com/script_upload.php', data)

Example: test-upload.py

posting multipart/form-data in Python:

• http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/146306

timeoutsocket.py: overriding Python socket API:

• http://www.timo-tasi.org/python/timeoutsocket.py
• http://mail.python.org/pipermail/python-announce-list/2001-December/001095.html