diff --git a/.travis.yml b/.travis.yml
index 5cc487d..b11950f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,21 +2,19 @@
 
 sudo: false
 language: python
-
-matrix:
-    include:
-      - python: 2.7
-        env: TOX_ENV=py27
-      - python: pypy
-        env: TOX_ENV=pypy
-      - python: 3.6
-        env: TOX_ENV=flake8
+python:
+  - "2.7"
+  - "3.3"
+  - "3.4"
+  - "3.5"
+  - "3.6"
+  - "pypy"
 
 install:
-  - pip install tox
+  - pip install tox-travis
 
 script:
-  - tox -e $TOX_ENV
+  - tox -v
 
 before_cache:
   - rm -rf $HOME/.cache/pip/log
diff --git a/appveyor.yml b/appveyor.yml
index 32bb8ca..dd1a26d 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,6 +6,18 @@ environment:
     - PYTHON: "C:\\Python27"
       TOX_ENV: "py27"
 
+    - PYTHON: "C:\\Python33"
+      TOX_ENV: "py33"
+
+    - PYTHON: "C:\\Python34"
+      TOX_ENV: "py34"
+
+    - PYTHON: "C:\\Python35"
+      TOX_ENV: "py35"
+
+    - PYTHON: "C:\\Python36"
+      TOX_ENV: "py36"
+
 init:
   - "%PYTHON%/python -V"
   - "%PYTHON%/python -c \"import struct;print( 8 * struct.calcsize(\'P\'))\""
@@ -18,7 +30,7 @@ install:
 build: false  # Not a C# project, build stuff at the test step instead.
 
 test_script:
-  - "%PYTHON%/Scripts/tox -e %TOX_ENV%"
+  - "%PYTHON%/Scripts/tox -v -e %TOX_ENV%"
 
 after_test:
   - "%PYTHON%/python setup.py bdist_wheel"
diff --git a/pytest_socket.py b/pytest_socket.py
index 7a8f543..7c50fa1 100644
--- a/pytest_socket.py
+++ b/pytest_socket.py
@@ -1,45 +1,64 @@
 # -*- coding: utf-8 -*-
 import socket
-import sys
 
 import pytest
 
-_module = sys.modules[__name__]
+_true_socket = socket.socket
 
 
-def pytest_runtest_setup():
-    """ disable the internet. test-cases can explicitly re-enable """
+class SocketBlockedError(RuntimeError):
+    def __init__(self, *args, **kwargs):
+        super(SocketBlockedError, self).__init__("A test tried to use socket.socket.")
+
+
+def pytest_addoption(parser):
+    group = parser.getgroup('socket')
+    group.addoption(
+        '--disable-socket',
+        action='store_true',
+        dest='disable_socket',
+        help='Disable socket.socket by default to block network calls.'
+    )
+
+
+@pytest.fixture(autouse=True)
+def _socket_marker(request):
+    if request.node.get_marker('disable_socket'):
+        request.getfixturevalue('socket_disabled')
+    if request.node.get_marker('enable_socket'):
+        request.getfixturevalue('socket_enabled')
+
+    if request.config.getoption('--disable-socket'):
+        request.getfixturevalue('socket_disabled')
+
+
+@pytest.fixture
+def socket_disabled():
+    """ disable socket.socket for duration of this test function """
     disable_socket()
+    yield
+    enable_socket()
 
 
-@pytest.fixture(scope='function')
-def socket_enabled(request):
-    """ re-enable socket.socket for duration of this test function """
+@pytest.fixture
+def socket_enabled():
+    """ enable socket.socket for duration of this test function """
     enable_socket()
-    request.addfinalizer(disable_socket)
+    yield
+    disable_socket()
 
 
 def disable_socket():
     """ disable socket.socket to disable the Internet. useful in testing.
     """
-    setattr(_module, u'_socket_disabled', True)
 
     def guarded(*args, **kwargs):
-        if getattr(_module, u'_socket_disabled', False):
-            raise RuntimeError(
-                u"A test tried to use socket.socket without explicitly un-blocking it.")
-        else:
-            # SocketType is a valid, public alias of socket.socket,
-            # we use it here to avoid namespace collisions
-            return socket.SocketType(*args, **kwargs)
+        raise SocketBlockedError()
 
     socket.socket = guarded
 
-    print(u'[!] socket.socket is now blocked. The network should be inaccessible.')
-
 
 def enable_socket():
     """ re-enable socket.socket to enable the Internet. useful in testing.
     """
-    setattr(_module, u'_socket_disabled', False)
-    print(u'[!] socket.socket is UN-blocked, and the network can be accessed.')
+    socket.socket = _true_socket
diff --git a/setup.py b/setup.py
index 9f5a7a7..9f7246e 100644
--- a/setup.py
+++ b/setup.py
@@ -23,7 +23,7 @@ def read(fname):
     description='Pytest Plugin to disable socket calls during tests',
     long_description=read('README.rst'),
     py_modules=['pytest_socket'],
-    install_requires=['pytest>=3.1.1'],
+    install_requires=['pytest>=3.0.0'],
     classifiers=[
         'Development Status :: 4 - Beta',
         'Framework :: Pytest',
diff --git a/tests/test_socket.py b/tests/test_socket.py
index 6ec0540..6ea5c7d 100644
--- a/tests/test_socket.py
+++ b/tests/test_socket.py
@@ -1,41 +1,185 @@
 # -*- coding: utf-8 -*-
+import pytest
 
+from pytest_socket import enable_socket
 
-def test_disabled_socket_fails(testdir):
+
+@pytest.fixture(autouse=True)
+def reenable_socket():
+    # The tests can leave the socket disabled in the global scope.
+    # Fix that by automatically re-enabling it after each test
+    yield
+    enable_socket()
+
+
+def assert_socket_blocked(result):
+    result.stdout.fnmatch_lines("""
+        *SocketBlockedError: A test tried to use socket.socket.*
+    """)
+
+
+def test_socket_enabled_by_default(testdir):
     testdir.makepyfile("""
         import socket
+
+        def test_socket():
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    """)
+    result = testdir.runpytest("--verbose")
+    result.assert_outcomes(1, 0, 0)
+    with pytest.raises(Exception):
+        assert_socket_blocked(result)
+
+
+def test_global_disable_via_fixture(testdir):
+    testdir.makepyfile("""
+        import pytest
+        import pytest_socket
+        import socket
+
+        @pytest.fixture(autouse=True)
+        def disable_socket_for_all():
+            pytest_socket.disable_socket()
+
         def test_socket():
             socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     """)
     result = testdir.runpytest("--verbose")
     result.assert_outcomes(0, 0, 1)
-    result.stdout.fnmatch_lines("""
-        *RuntimeError: A test tried to use socket.socket without explicitly un-blocking it.*
+    assert_socket_blocked(result)
+
+
+def test_global_disable_via_cli_flag(testdir):
+    testdir.makepyfile("""
+        import socket
+
+        def test_socket():
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     """)
+    result = testdir.runpytest("--verbose", "--disable-socket")
+    result.assert_outcomes(0, 0, 1)
+    assert_socket_blocked(result)
 
 
-def test_disabled_httplib_fails(testdir):
+def test_global_disable_via_config(testdir):
     testdir.makepyfile("""
-        import httplib
-        def test_httplib():
-            httplib.HTTPConnection("scanme.nmap.org:80").request("GET", "/")
+        import socket
+
+        def test_socket():
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    """)
+    testdir.makeini("""
+        [pytest]
+        addopts = --disable-socket
     """)
     result = testdir.runpytest("--verbose")
     result.assert_outcomes(0, 0, 1)
-    result.stdout.fnmatch_lines("""
-        *RuntimeError: A test tried to use socket.socket without explicitly un-blocking it.*
+    assert_socket_blocked(result)
+
+
+def test_disable_socket_marker(testdir):
+    testdir.makepyfile("""
+        import pytest
+        import socket
+
+        @pytest.mark.disable_socket
+        def test_socket():
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     """)
+    result = testdir.runpytest("--verbose")
+    result.assert_outcomes(0, 0, 1)
+    assert_socket_blocked(result)
+
+
+def test_enable_socket_marker(testdir):
+    testdir.makepyfile("""
+        import pytest
+        import socket
+
+        @pytest.mark.enable_socket
+        def test_socket():
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    """)
+    result = testdir.runpytest("--verbose", "--disable-socket")
+    result.assert_outcomes(0, 0, 1)
+    assert_socket_blocked(result)
+
+
+def test_urllib_succeeds_by_default(testdir):
+    testdir.makepyfile("""
+        try:
+            from urllib.request import urlopen
+        except ImportError:
+            from urllib2 import urlopen
+
+        def test_disable_socket_urllib():
+            assert urlopen('http://httpbin.org/get').getcode() == 200
+    """)
+    result = testdir.runpytest("--verbose")
+    result.assert_outcomes(1, 0, 0)
+
+
+def test_enabled_urllib_succeeds(testdir):
+    testdir.makepyfile("""
+        import pytest
+        import pytest_socket
+        try:
+            from urllib.request import urlopen
+        except ImportError:
+            from urllib2 import urlopen
+
+        @pytest.mark.enable_socket
+        def test_disable_socket_urllib():
+            assert urlopen('http://httpbin.org/get').getcode() == 200
+    """)
+    result = testdir.runpytest("--verbose", "--disable-socket")
+    result.assert_outcomes(0, 0, 1)
+    assert_socket_blocked(result)
+
+
+def test_disabled_urllib_fails(testdir):
+    testdir.makepyfile("""
+        import pytest
+        try:
+            from urllib.request import urlopen
+        except ImportError:
+            from urllib2 import urlopen
+
+        @pytest.mark.disable_socket
+        def test_disable_socket_urllib():
+            assert urlopen('http://httpbin.org/get').getcode() == 200
+    """)
+    result = testdir.runpytest("--verbose")
+    result.assert_outcomes(0, 0, 1)
+    assert_socket_blocked(result)
 
 
-def test_enabling_while_enabled_does_nothing(testdir):
+def test_double_call_does_nothing(testdir):
     testdir.makepyfile("""
+        import pytest
         import pytest_socket
-        def test_enabled():
+        import socket
+
+        def test_double_enabled():
+            pytest_socket.enable_socket()
             pytest_socket.enable_socket()
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+        def test_double_disabled():
+            pytest_socket.disable_socket()
+            pytest_socket.disable_socket()
+            with pytest.raises(pytest_socket.SocketBlockedError):
+                socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+        def test_disable_enable():
+            pytest_socket.disable_socket()
             pytest_socket.enable_socket()
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     """)
     result = testdir.runpytest("--verbose")
-    result.assert_outcomes(1, 0, 0)
+    result.assert_outcomes(3, 0, 0)
+    with pytest.raises(Exception):
+        assert_socket_blocked(result)
 
 
 def test_socket_enabled_fixture(testdir, socket_enabled):
@@ -46,11 +190,14 @@ def test_socket_enabled(socket_enabled):
     """)
     result = testdir.runpytest("--verbose")
     result.assert_outcomes(1, 0, 0)
+    with pytest.raises(Exception):
+        assert_socket_blocked(result)
 
 
 def test_mix_and_match(testdir, socket_enabled):
     testdir.makepyfile("""
         import socket
+
         def test_socket1():
             socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         def test_socket_enabled(socket_enabled):
@@ -58,5 +205,5 @@ def test_socket_enabled(socket_enabled):
         def test_socket2():
             socket.socket(socket.AF_INET, socket.SOCK_STREAM)
     """)
-    result = testdir.runpytest("--verbose")
+    result = testdir.runpytest("--verbose", "--disable-socket")
     result.assert_outcomes(1, 0, 2)
diff --git a/tox.ini b/tox.ini
index 3747c71..86fe7a1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 # For more information about tox, see https://tox.readthedocs.io/en/latest/
 [tox]
-envlist = py27,pypy,flake8
+envlist = py27,py33,py34,py35,py36,pypy,flake8
 
 [testenv]
 deps = pytest