netdiff

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Netdiff is a simple abstraction layer for parsing network topology data of open source dynamic routing protocols or any other networking software which has knowledge about the topology of a network.

Its goal is to allow applications like openwisp-network-topology <https://github.com/openwisp/openwisp-network-topology>_ to collect, visualize and monitor network topology data without having to deal with the details of each networking software from which the data is retrieved.

Features:

• parse different formats <https://github.com/openwisp/netdiff#parsers>_
• detect changes in two topologies <https://github.com/openwisp/netdiff#basic-usage-example>_
• return consistent NetJSON output <https://github.com/openwisp/netdiff#netjson-output>_
• uses the popular networkx <https://networkx.github.io/>_ library under the hood

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.. contents:: Table of Contents: :backlinks: none :depth: 3

Install stable version from pypi

Install from pypi:

.. code-block:: shell

pip install netdiff

Install development version

Install tarball:

.. code-block:: shell

pip install https://github.com/openwisp/netdiff/tarball/master

Alternatively you can install via pip using git:

.. code-block:: shell

pip install -e git+git://github.com/openwisp/netdiff#egg=netdiff

If you want to contribute, install your cloned fork:

.. code-block:: shell

git clone [email protected]:<your_fork>/netdiff.git
cd netdiff
python setup.py develop

Basic Usage Example

Calculate diff of an OLSR 0.6.x topology:

.. code-block:: python

from netdiff import OlsrParser
from netdiff import diff

old = OlsrParser(file='./stored-olsr.json')
new = OlsrParser(url='http://127.0.0.1:9090')
diff(old, new)

In alternative, you may also use the subtraction operator:

.. code-block:: python

from netdiff import OlsrParser
from netdiff import diff

old = OlsrParser(file='./stored-olsr.json')
new = OlsrParser(url='http://127.0.0.1:9090')
old - new

The output will be an ordered dictionary with three keys:

• added
• removed
• changed

Each key will contain a dict compatible with the NetJSON NetworkGraph_ format representing respectively:

• the nodes and links that have been added to the topology
• the nodes and links that have been removed from the topology
• the nodes and links that are present in both topologies but their attributes have changed

If no changes are present, keys will contain None.

So if between old and new there are no changes, the result will be:

.. code-block:: python

{
    "added": None
    "removed": None,
    "changed": None
}

While if there are changes, the result will look like:

.. code-block:: python

{
    "added": {
        "type": "NetworkGraph",
        "protocol": "OLSR",
        "version": "0.6.6",
        "revision": "5031a799fcbe17f61d57e387bc3806de",
        "metric": "ETX",
        "nodes": [
            {
                "id": "10.150.0.7",
                "label": "Node A",
                "local_addresses": [],
                "properties": {}
            },
            {
                "id": "10.150.0.6",
                "label": "Node B",
                "local_addresses": ["10.56.2.1"],
                "properties": {
                    "hostname": "nodeb.lan"
                }
            }
        ],
        "links": [
            {
                "source": "10.150.0.3",
                "target": "10.150.0.7",
                "cost": 1.50390625,
                "cost_text", "",
                "properties": {}
            },
            {
                "source": "10.150.0.3",
                "target": "10.150.0.6",
                "cost": 1.0
                "cost_text", "",
                "properties": {}
            }
        ]
    },
    "removed": {
        "type": "NetworkGraph",
        "protocol": "OLSR",
        "version": "0.6.6",
        "revision": "5031a799fcbe17f61d57e387bc3806de",
        "metric": "ETX",
        "nodes": [
            {
                "id": "10.150.0.8",
                "label": "Node C",
                "local_addresses": [],
                "properties": {}
            }
        ],
        "links": [
            {
                "source": "10.150.0.7",
                "target": "10.150.0.8",
                "cost": 1.0
                "cost_text", "",
                "properties": {}
            }
        ]
    },
    "changed": {
        "type": "NetworkGraph",
        "protocol": "OLSR",
        "version": "0.6.6",
        "revision": "5031a799fcbe17f61d57e387bc3806de",
        "metric": "ETX",
        "nodes": [],
        "links": [
            {
                "source": "10.150.0.3",
                "target": "10.150.0.2",
                "cost": 1.0
                "cost_text", "",
                "properties": {}
            }
        ]
    }
}

Parsers

Parsers are classes that extend netdiff.base.BaseParser and implement a parse method which is in charge of converting a python data structure into networkx.Graph object and return the result.

Parsers also have a json method which returns valid NetJSON output <https://github.com/openwisp/netdiff#netjson-output>_.

The available parsers are:

• netdiff.OlsrParser: parser for the olsrd jsoninfo plugin <http://www.olsr.org/?q=jsoninfo_plugin>_ or the older txtinfo plugin <http://www.olsr.org/?q=txtinfo_plugin>_
• netdiff.BatmanParser: parser for the batman-advanced alfred tool <http://www.open-mesh.org/projects/open-mesh/wiki/Alfred>_ (supports also the legacy txtinfo format inherited from olsrd)
• netdiff.Bmx6Parser: parser for the BMX6 b6m tool <http://dev.qmp.cat/projects/b6m>_
• netdiff.CnmlParser: parser for CNML 0.1 <http://en.wiki.guifi.net/wiki/CNML>_
• netdiff.NetJsonParser: parser for the NetJSON NetworkGraph_ format
• netdiff.OpenvpnParser: parser for the OpenVPN status file <https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage>_
• netdiff.WireguardParser: parser for the Wireguard VPN (the command to use is wg show all dump)

Initialization arguments

Data can be supplied in 3 different ways, in the following order of precedence:

* ``data``: ``dict`` or ``str`` representing the topology/graph
* ``url``: URL to fetch data from
* ``file``: file path to retrieve data from

Other available arguments:

* **timeout**: integer representing timeout in seconds for HTTP or telnet requests, defaults to ``None``
* **verify**: boolean indicating to the `request library whether to do SSL certificate
  verification or not <http://docs.python-requests.org/en/latest/user/advanced/#ssl-cert-verification>`_
* **directed**: boolean that enables the use of a directed graph (``networkx.DiGraph``), defaults to ``False``

Initialization examples
~~~~~~~~~~~~~~~~~~~~~~~

Local file example:

.. code-block:: python

    from netdiff import BatmanParser
    BatmanParser(file='./my-stored-topology.json')

HTTP example:

.. code-block:: python

    from netdiff import NetJsonParser
    url = 'https://raw.githubusercontent.com/interop-dev/netjson/master/examples/network-graph.json'
    NetJsonParser(url=url)

Telnet example with ``timeout``:

.. code-block:: python

    from netdiff import OlsrParser
    OlsrParser(url='telnet://127.0.1', timeout=5)

HTTPS example with self-signed SSL certificate using ``verify=False``:

.. code-block:: python

    from netdiff import NetJsonParser
    OlsrParser(url='https://myserver.mydomain.com/topology.json', verify=False)

NetJSON output
--------------

Netdiff parsers can return a valid `NetJSON NetworkGraph`_ object:

.. code-block:: python

    from netdiff import OlsrParser

    olsr = OlsrParser(url='telnet://127.0.0.1:9090')

    # will return a dict
    olsr.json(dict=True)

    # will return a JSON formatted string
    print(olsr.json(indent=4))

Output:

.. code-block:: javascript

    {
        "type": "NetworkGraph",
        "protocol": "OLSR",
        "version": "0.6.6",
        "revision": "5031a799fcbe17f61d57e387bc3806de",
        "metric": "ETX",
        "nodes": [
            {
                "id": "10.150.0.3"
            },
            {
                "id": "10.150.0.2"
            },
            {
                "id": "10.150.0.4"
            }
        ],
        "links": [
            {
                "source": "10.150.0.3",
                "target": "10.150.0.2",
                "cost": 2.4
            },
            {
                "source": "10.150.0.3",
                "target": "10.150.0.4",
                "cost": 1.0
            }
        ]
    }

Exceptions
----------

All the exceptions are subclasses of ``netdiff.exceptions.NetdiffException``.

ConversionException
~~~~~~~~~~~~~~~~~~~

``netdiff.exceptions.ConversionException``

Raised when netdiff can't recognize the format passed to the parser.

Not necessarily an error, should be caught and managed in order to support additional formats.

The data which was retrieved from network/storage can be accessed via the "data" attribute, eg:

.. code-block:: python

    def to_python(self, data):
        try:
            return super().to_python(data)
        except ConversionException as e:
            return self._txtinfo_to_jsoninfo(e.data)

ParserError
~~~~~~~~~~~

``netdiff.exceptions.ParserError``

Raised when the format is recognized but the data is invalid.

NetJsonError
~~~~~~~~~~~~

``netdiff.exceptions.NetJsonError``

Raised when the ``json`` method of ``netdiff.parsers.BaseParser`` does not have enough data
to be compliant with the `NetJSON NetworkGraph`_ specification.

TopologyRetrievalError
~~~~~~~~~~~~~~~~~~~~~~

``netdiff.exceptions.TopologyRetrievalError``

Raised when it is not possible to retrieve the topology data
(eg: the URL might be temporary unreachable).

Specialized features
--------------------

OpenVPN
~~~~~~~

By default, the OpenVPN parser uses the common name to identify a client,
this was chosen because if the public IP address is used, the same client
will not be recognized if it connects with a different IP address
(very probable since many ISPs use dynamic public IP addresses).

This does not work when the vpn server configuration allows different clients
to use the same common name (which is generally not recommended anyway).

If you need to support legacy systems which are configured with the OpenVPN
``duplicate-cn`` feature enabled, you can pass ``duplicate_cn=True`` during
the initialization of ``OpenvpnParser``.
This will change the behavior of the parser so that each client is identified
by their common name and IP address (and additionally the port used if there
are multiple clients with same common name and IP).

Known Issues
------------

ConnectionError: BadStatusLine

If you get a similar error when performing a request to the jsoninfo plugin <http://www.olsr.org/?q=jsoninfo_plugin>_ of olsrd <http://www.olsr.org/>_ (version 0.6 to 0.9) chances are high that http headers are disabled.

To fix it turn on http headers in your olsrd configuration file, eg::

LoadPlugin "olsrd_jsoninfo.so.0.0"
{
    PlParam "httpheaders" "yes"   # add this line
    PlParam "Port" "9090"
    PlParam "accept" "0.0.0.0"
}

Running tests

Install your forked repo:

.. code-block:: shell

git clone git://github.com/<your_fork>/netdiff
cd netdiff/
python setup.py develop

Install test requirements:

.. code-block:: shell

pip install -r requirements-test.txt

Run tests with:

.. code-block:: shell

./runtests.py
./run-qa-checks

Alternatively, you can use the nose2 command (which has a ton of available options):

.. code-block:: shell

nose2
nose2 tests.test_olsr  # run only olsr related tests
nose2 tests/test_olsr.py  # variant form of the previous command
nose2 tests.test_olsr:TestOlsrParser  # variant form of the previous command
nose2 tests.test_olsr:TestOlsrParser.test_parse  # run specific test

See test coverage with:

.. code-block:: shell

coverage run --source=netdiff runtests.py && coverage report

Contributing

Please refer to the OpenWISP contributing guidelines <http://openwisp.io/docs/developer/contributing.html>_.

Support

See OpenWISP Support Channels <http://openwisp.org/support.html>_.

Changelog

See CHANGES <https://github.com/openwisp/netdiff/blob/master/CHANGES.rst>_.

License

See LICENSE <https://github.com/openwisp/netdiff/blob/master/LICENSE>_.

.. _NetJSON NetworkGraph: http://netjson.org/rfc.html#rfc.section.4