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Mininet 2.3.0 Release Notes

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lantz edited this page Jun 22, 2021 · 123 revisions
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Welcome to Mininet 2.3.0!

Please read these Release Notes carefully, and enjoy using Mininet!

Python 3 Support

Mininet 2.3.0 brings Python 3 support to Mininet!

Python 2 is still supported by Mininet 2.3.0, but it may become harder to use over time because of official deprecation by the CPython project as well as eroding support from Linux distributions such as Ubuntu. Nonetheless it should be possible to install both Python 2 and Python 3 versions of Mininet in Ubuntu 20.04 LTS, and the Mininet 2.3.0 VMs include both Python 2 and Python 3. In the future we may wish to explore running under pypy for Python 2 as it may be better supported.

To install a Python 2 mn command:

  PYTHON=python2 mininet/util/install.sh -n

To install Python 3 mn:

  PYTHON=python3 mininet/util/install.sh -n

Note that -n just installs mn and the base Mininet dependencies. Typically for a minimal usable Mininet you might want -nfv for Mininet, the (OpenFlow 1.0) user switch and controller, and Open vSwitch.

To run mn using Python 3 explicitly:

  sudo python3 `which mn`

To run mn using Python 2 explicitly:

  sudo python2 `which mn`

To find out which version of Python mn is using by default:

  echo py sys.version_info | sudo mn -v output

or

  sudo mn
  ...
  mininet> py sys.version_info

Other Features and Changes

  • RyuController has been simplified and updated for the current Ryu

    The Ryu() constructor has changed slightly. We still add --ofp-tcp-listen-port %s to the end of cargs to make Controller() happy.

    command is now ryu run so it includes the run command but can be specified explicitly as needed.

    You should be able to run Ryu's simple_switch by using:

     mn --controller ryu

    and pass alternate modules such as simple_switch_13:

     mn --controller ryu,ryu.app.simple_switch_13

  • Mininet continuous integration (CI) testing has switched from Travis to Github Actions. Thanks to Travis.org for years of helpful CI support for Mininet and other open source projects.

  • Mininet CI testing currently tests Mininet 2.3.0 on Ubuntu 20.04, 18.04, 16.04 for 64-bit/amd64 and 16.04 for 32-bit/i386.

  • Premade Mininet VMs are currently being built on an experimental basis using Github Actions at https://github.com/mininet/vm-build/actions .

  • Many scripts in the Mininet source tree now start with #!/usr/bin/env python to facilitate use with virtualenv. See below for important security information.

Security Warnings and Advisories

  • Scripts included in Mininet 2.3.0 (such as mn and examples/* now use #!/usr/bin/env python to facilitate direct use with virtualenv. This seems like the right thing to do to make it easier to use Mininet with virtualenv (and potentially Python IDEs that use virtualenv.)

    However, it is worth noting that this could open up a security hole or reliability issue if you end up executing an unexpected Python interpreter in your path.

    Note when mn is installed (for example using install.sh -n or PYTHON=python sudo make install this #! line will be changed to refer to the interpreter used for the installation.

  • Note that Mininet in general runs as root (at least until we change it to use more granular capabilities) so for safety we recommend running it in a virtual (or other) machine that you don't mind destroying accidentally. If you run it in your main OS, you should be careful to avoid running unexpected or undesired code with root privileges. Note that VM execution isn't 100% secure; virtual drivers often contain bugs that can enable VM escape or privilege escalation.

  • Official Mininet 2.3.0 VMs do not include any SSH (server or client) keys; instead they are regenerated in /etc/rc.local. Please do not distribute Mininet (or other) VM images that include SSH server server or client keys (as some people have done for courses, tutorials, etc.) since using identical, publicly visible SSH keys compromises SSH privacy and also allows the VM image to be impersonated or MITMed.

  • An unofficial pypi repo has been created by third parties; we do not currently recommend its use because:

    • It may not contain the specific released code from the Mininet repo
    • Mininet cannot currently be fully installed using pip or pip3 (it requires mnexec, which must be compiled for the particular architecture such as arm64, i386, armhf, etc.)

Errata

  • Although Mininet 2.3.0 uses pip and pip3 to install itself from source, this does not currently install all of the base requirements for running Mininet (notably mnexec and its documentation), and uninstalling it only removes the Python components. Note that mnexec must be compiled for the appropriate architecture (arm64, i386, armhf etc..) In the future we may be able to create a pip package that includes binaries for a variety of architectures, or we may include a pure Python version of mnexec which would work across architectures. As noted above, we do not currently recommend the third-party, unofficial pip packages from pypi.

  • install.sh -3f currently fails on Ubuntu 20 due to the https://github.com/CPqD/ofsoftswitch13 build being broken. Hopefully this can be resolved in the upstream project.

  • net.waitConnected() currently hangs with ofsoftswitch13 due to dpctl not working as expected. As a workaround, please specify a timeout (e.g. --twait 5).

  • Some tests dump their output to stdout; this was changed to help diagnose some test failures seen running on GitHub Actions CI but not when run locally.

  • To generate the API documentation, we are still using the older doxypy and installing it using pip. We may switch from doxypy to doxypypy in the future, but python3-doxypypy seems to be broken in Ubuntu 20.04. Hopefully this will be fixed in the future and we may be able to switch to doxypypy.

  • Installation on {Fedora, RHEL, OpenSUSE, Raspbian, etc.} has not been fully tested and may be revised at a future date. Ubuntu is tested in CI, and Debian 10 passed all tests in manual testing.

  • install.sh -fnv on Fedora 33 does not appear to install all dependencies, and make test currently has many test failures, some of them apparently related to performance modeling (e.g. CPULimitedHost and TCIntf.) We welcome pull requests to enable all of the tests to pass on Fedora and other distributions.

  • VM Images should have the correct 2.3.0 final installation, but the active branch may be master rather than a branch corresponding to 2.3.0. To check out a specific 2.3.0 branch, use

    cd ~/mininet; git checkout -b v2.3.0 2.3.0

  • Wireshark in Ubuntu doesn't work out of the box with XQuartz (macOS), resulting in the error Could not load the Qt platform plugin "xcb"…. This seems to be due to libdouble-conversion being broken. To fix it in Ubuntu 20.04:

    $ dpkg -l | grep libdouble-conversion  # to see which version you have
$ sudo apt remove libdouble-conversion3  # be sure to specify the right version
$ sudo apt autoremove  # get rid of things that depend on library, including wireshark
$ sudo apt install wireshark  # reinstall wireshark

  • mnexec -v for Mininet 2.3.0 prints a blank line rather than the correct version number #1052 (fixed in master)

  • MiniEdit might not save or load topologies properly when running under Python 3, and may have other issues #1049 (fixed in master)

  • Debian packaging in the Mininet github repo is not up to date but may be updated in the future.

  • By default, Ryu uses fairly verbose and slow logging. Unfortunately it is hard to turn this off since the cargs parameter is expected to contain %d and a TypeError will be raised otherwise. As a workaround in 2.3.0 you can may be able to use --user-flags:

    sudo mn --controller ryu,cargs='ryu.app.simple_switch --default-log-level=30 --user-flags=%d' -w ...

Acknowledgments

Thanks to Tomasz Buchert and Santiago Ruano Rincón for packaging and release support in Debian 11 Bullseye!

Thanks to the FAUCET project and Google for supporting the Python 3 work.

Thanks to all of the Mininet users and contributors!