This goal of this project is to provide a consistent interface to LBL's libpcap
packet capture library. This project was created because the currently
available ruby-pcap library is poorly designed and has been unmaintained since
2000. This does not provide packet processing functionality, it simply provides
the interface for capturing packets. For packet processing capability, see the
PacketRub project (http://packetrub.rubyforge.org).

Requirements:
  libpcap - http://www.tcpdump.org

Build & Install:
  ruby extconf.rb && make && make install

The latest version can be obtained from Subversion:
  svn checkout http://pcaprub.rubyforge.org/svn/trunk/

The Metasploit Project also provides a Subversion repository:
  svn checkout http://metasploit.com/svn/framework3/trunk/external/pcaprub/

The Metasploit Project also added some code from the python netifaces c extension

Original c/python netifaces code is under MIT-style license.  
Here goes:

Copyright (c) 2007, 2008 Alastair Houghton

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.