ARPwner is a tool to do ARP poisoning and DNS poisoning attacks, with a simple GUI and a plugin system to do filtering of the information gathered, also has a implementation of sslstrip and is coded 100% in python and on Github, so you can modify according to your needs.
This tool was released by Nicolas Trippar at BlackHat USA 2012.
For the tool to work you need pypcap, so assuming are using a Debian derivative OS (like all sane people do) – you’ll need to do this first:
apt-get install python-pypcap
You can download ARPwner here: ARPwner.zip
Or read more here.