Ostinato
Ostinato is an open-source, cross-platform network packet crafter/traffic generator and analyzer with a friendly GUI and powerful python API. Craft and send packets of several streams with different protocols at different rates.
Ostinato aims to be "Wireshark in Reverse" and become complementary to Wireshark.
License: GPLv3+ (see COPYING)
For more information visit http://ostinato.org.