Selenium Webdrive socket.error

I using Ubuntu x64

When I execute fallowing code:

from selenium import webdriver
x = webdriver.Firefox()
x.get('any address')

I get the fallowing error:

 % python seleniumtest.py 
Traceback (most recent call last):
  File "seleniumtest.py", line 2, in <module>
    x = webdriver.Firefox()
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.py", line 85, in __init__
    keep_alive=True)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 90, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 177, in start_session
    response = self.execute(Command.NEW_SESSION, capabilities)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 234, in execute
    response = self.command_executor.execute(driver_command, params)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/remote_connection.py", line 401, in execute
    return self._request(command_info[0], url, body=data)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/remote_connection.py", line 432, in _request
    resp = self._conn.getresponse()
  File "/usr/lib/python2.7/httplib.py", line 1051, in getresponse
    response.begin()
  File "/usr/lib/python2.7/httplib.py", line 415, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python2.7/httplib.py", line 371, in _read_status
    line = self.fp.readline(_MAXLINE + 1)
  File "/usr/lib/python2.7/socket.py", line 476, in readline
    data = self._sock.recv(self._rbufsize)
socket.error: [Errno 104] Connection reset by peer

What is this problem? how to can I fix this?

---

This problem I resolved executing fallowing command in terminal:

terminal 1: % sudo Xvfb :10 -ac terminal 2: $ export DISPLAY=:10

Executing fallowing code:

from selenium import webdriver
from selenium.webdriver.common.keys import Keys

driver = webdriver.Firefox()
driver.get("http://www.python.org")
assert "Python" in driver.title
elem = driver.find_element_by_name("q")
elem.clear()
elem.send_keys("pycon")
elem.send_keys(Keys.RETURN)
assert "No results found." not in driver.page_source
driver.close()

Is returning this error:

 % python seleniumtest.py
Traceback (most recent call last):
  File "seleniumtest.py", line 4, in <module>
    driver = webdriver.Firefox()
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.py", line 81, in __init__
    self.binary, timeout)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/extension_connection.py", line 51, in __init__
    self.binary.launch_browser(self.profile, timeout=timeout)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/firefox_binary.py", line 68, in launch_browser
    self._wait_until_connectable(timeout=timeout)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/firefox_binary.py", line 98, in _wait_until_connectable
    raise WebDriverException("The browser appears to have exited "
selenium.common.exceptions.WebDriverException: Message: The browser appears to have exited before we could connect. If you specified a log_file in the FirefoxBinary constructor, check it for details.

---

My Firefox and Selenium version:

% firefox -v
Mozilla Firefox 47.0

 % pip show selenium
---
Metadata-Version: 2.0
Name: selenium
Version: 2.53.5
Summary: Python bindings for Selenium
Home-page: https://github.com/SeleniumHQ/selenium/
Author: UNKNOWN
Author-email: UNKNOWN
Installer: pip
License: UNKNOWN
Location: /usr/local/lib/python2.7/dist-packages
Requires: 
Classifiers:
  Development Status :: 5 - Production/Stable
  Intended Audience :: Developers
  License :: OSI Approved :: Apache Software License
  Operating System :: POSIX
  Operating System :: Microsoft :: Windows
  Operating System :: MacOS :: MacOS X
  Topic :: Software Development :: Testing
  Topic :: Software Development :: Libraries
  Programming Language :: Python
  Programming Language :: Python :: 2.6
  Programming Language :: Python :: 2.7
  Programming Language :: Python :: 3.2
  Programming Language :: Python :: 3.3
  Programming Language :: Python :: 3.4