libpcap

Python binding for the libpcap C library.

Overview

Python libpcap module is a low-level binding for libpcap C library.

It is an effort to allow python programs full access to the API provided by the well known libpcap Unix C library and by its implementations provided under Win32 systems by such packet capture systems as: Npcap, WinPcap

libpcap is a lightweight Python package, based on the ctypes library.

It is fully compliant implementation of the original C libpcap from 1.0.0 up to 1.9.0 API and the WinPcap's 4.1.3 libpcap (1.0.0rel0b) API by implementing whole its functionality in a clean Python instead of C.

Useful libpcap API documentation can be found at:

Main pcap man page,

(MORE pcap man pages)

libpcap uses the underlying libpcap C shared library as specified in libpcap.cfg (system's libpcap shared library is the default), but there is also ability to specify it programmatically by one of the following ways:

import libpcap
libpcap.config(LIBPCAP=None)       # system's libpcap library will be use
# or
libpcap.config(LIBPCAP="npcap")
# or
libpcap.config(LIBPCAP="wpcap")    # included wpcap library will be use
# or
libpcap.config(LIBPCAP="tcpdump")  # included tcpdump library will be use
# or                               # (currently works only for Linux x64)
libpcap.config(LIBPCAP="libpcap shared library absolute path")

About original LIBPCAP:

LIBPCAP 1.x.y

Now maintained by "The Tcpdump Group":

https://www.tcpdump.org

Anonymous Git is available via:

git clone git://bpf.tcpdump.org/libpcap

formerly from:

Lawrence Berkeley National Laboratory

Network Research Group <[email protected]>

ftp://ftp.ee.lbl.gov/old/libpcap-0.4a7.tar.Z

This directory contains source code for libpcap, a system-independent interface for user-level packet capture. libpcap provides a portable framework for low-level network monitoring. Applications include network statistics collection, security monitoring, network debugging, etc. Since almost every system vendor provides a different interface for packet capture, and since we've developed several tools that require this functionality, we've created this system-independent API to ease in porting and to alleviate the need for several system-dependent packet capture modules in each application.

For some platforms there are README.{system} files that discuss issues with the OS's interface for packet capture on those platforms, such as how to enable support for that interface in the OS, if it's not built in by default.

The libpcap interface supports a filtering mechanism based on the architecture in the BSD packet filter. BPF is described in the 1993 Winter Usenix paper "The BSD Packet Filter: A New Architecture for User-level Packet Capture". A compressed PostScript version can be found at:

ftp://ftp.ee.lbl.gov/papers/bpf-usenix93.ps.Z

or:

https://www.tcpdump.org/papers/bpf-usenix93.ps.Z

and a gzipped version can be found at:

https://www.tcpdump.org/papers/bpf-usenix93.ps.gz

A PDF version can be found at:

https://www.tcpdump.org/papers/bpf-usenix93.pdf

Although most packet capture interfaces support in-kernel filtering, libpcap utilizes in-kernel filtering only for the BPF interface. On systems that don't have BPF, all packets are read into user-space and the BPF filters are evaluated in the libpcap library, incurring added overhead (especially, for selective filters). Ideally, libpcap would translate BPF filters into a filter program that is compatible with the underlying kernel subsystem, but this is not yet implemented.

BPF is standard in 4.4BSD, BSD/OS, NetBSD, FreeBSD, OpenBSD, DragonFly BSD, and Mac OS X; an older, modified and undocumented version is standard in AIX. DEC OSF/1, Digital UNIX, Tru64 UNIX uses the packetfilter interface but has been extended to accept BPF filters (which libpcap utilizes). Also, you can add BPF filter support to Ultrix using the kernel source and/or object patches available in:

https://www.tcpdump.org/other/bpfext42.tar.Z

Linux, in the 2.2 kernel and later kernels, has a "Socket Filter" mechanism that accepts BPF filters; see the README.linux file for information on configuring that option.

Note to Linux distributions and *BSD systems that include libpcap:

There's now a rule to make a shared library, which should work on Linux and *BSD, among other platforms.

It sets the soname of the library to "libpcap.so.1"; this is what it should be, NOT libpcap.so.1.x or libpcap.so.1.x.y or something such as that.

We've been maintaining binary compatibility between libpcap releases for quite a while; there's no reason to tie a binary linked with libpcap to a particular release of libpcap.

Current versions can be found at: https://www.tcpdump.org

- The TCPdump group

Requirements

• It is a fully independent package.

  All necessary things are installed during the normal installation process.

• ATTENTION: currently works and tested only for Windows.

Installation

Prerequisites:

• Python 3.6 or higher
  • https://www.python.org/
  • 3.7 with C LIBPCAP 1.8.1 is a primary test environment.
• pip and setuptools
  • https://pypi.org/project/pip/
  • https://pypi.org/project/setuptools/

To install run:

python -m pip install --upgrade libpcap

Development

Prerequisites:

• Development is strictly based on tox. To install it run:

  python -m pip install --upgrade tox
  

Visit development page.

Installation from sources:

clone the sources:

git clone https://github.com/karpierz/libpcap.git libpcap

and run:

python -m pip install ./libpcap

or on development mode:

python -m pip install --editable ./libpcap

License

Copyright (c) 2016-2020, Adam Karpierz

Licensed under the BSD license

https://opensource.org/licenses/BSD-3-Clause

Please refer to the accompanying LICENSE file.

Authors

• Adam Karpierz <[email protected]>