Python-pcapng
Python library to parse the pcap-ng format used by newer versions of dumpcap & similar tools (wireshark, winpcap, ...).
Documentation
If you prefer the RTD theme, or want documentation for any version other than the latest, head here:
http://python-pcapng.readthedocs.org/en/latest/
If you prefer the more comfortable, page-wide, default sphinx theme, a documentation mirror is hosted on GitHub pages:
http://rshk.github.io/python-pcapng/
CI build status
| Branch | Status |
|---|---|
| master | 
|
| develop | 
|
Source code
Source, issue tracker etc. on GitHub: https://github.com/rshk/python-pcapng
Get the source from git:
git clone https://github.com/rshk/python-pcapng
Download zip of the latest version:
https://github.com/rshk/python-pcapng/archive/master.zip
Install from pypi:
pip install python-pcapng
PyPI status
The official page on the Python Package Index is: https://pypi.python.org/pypi/python-pcapng
Why this library?
I need to decently extract some information from a bunch of pcap-ng files, but apparently tcpdump has some problems reading those files,
I couldn't find other nice tools nor Python bindings to a library able to parse this format, so..
In general, it appears there are (quite a bunch of!) Python modules to parse the old (much simpler) format, but nothing for the new one.
And, they usually completely lack any form of documentation.
Isn't it slow?
Yes, I guess it would be much slower than something written in C, but I'm much better at Python than C.
..and I need to get things done, and CPU time is not that expensive :)
(Maybe I'll give a try porting the thing to Cython to speed it up, but anyways, pure-Python libraries are always useful, eg. for PyPy).
How do I use it?
Basic usage is as simple as:
from pcapng import FileScanner
with open('/tmp/mycapture.pcap', 'rb') as fp:
scanner = FileScanner(fp)
for block in scanner:
pass # do something with the block...Have a look at the blocks documentation to see what they do; also, the
examples directory contains some example scripts using the library.
Hacking
Format specification is here:
https://github.com/pcapng/pcapng/
Contributions are welcome, please contact me if you're planning to do some big change, so that we can sort out the best way to integrate it.
Or even better, open an issue so the whole world can participate in the discussion :)
Pcap-ng write support
Write support exists as of version 2.0.0. See the file
examples/generate_pcapng.py for an example of the minimum code
needed to generate a pcapng file.
In most cases, this library will prevent you from creating broken data. If you want to create marginal pcapng files, e.g. as test cases for other software, you can do that by adjusting the "strictness" of the library, as in:
from pcapng.strictness import Strictness, set_strictness
set_strictness(Strictness.FIX)Recognized values are Strictness.FORBID (the default),
Strictness.FIX (warn about problems, fix if possible),
Strictness.WARN (warn only), and Strictness.NONE (no warnings).
Circumstances that will result in strictness warnings include:
- Adding multiples of a non-repeatable option to a block
- Adding a SPB to a file with more than one interface
- Writing a PB (PBs are obsolete and not to be used in new files)
- Writing EPB/SPB/PB/ISB before writing any IDBs
Creating a release
Create a tag for the new version:
git tag v2.0.0 -m 'Version 2.0.0'
Install build dependencies in a virtualenv:
python -m venv ./.build-venv ./.build-venv/bin/python -m pip install build twine
Build source and wheel distributions:
rm -rf ./dist *.egg-info ./.build-venv/bin/python -m build
Use Twine to upload to pypi:
twine upload dist/*
Troubleshooting
If you get some crazy version number like
2.0.1.dev0+g7bd8575.d20220310 instead of what you expect (eg
2.0.0), it's because you have uncommitted or untracked files in
your local working copy, or you created more commits after creating
the tag. Such a version number will be refused by pypi (and it's not a
good version number anyways), so make sure you have a clean working
copy before building.