Ostinato is an open-source, cross-platform packet/traffic generator and analyzer with a friendly GUI. It aims to be “Wireshark in Reverse” and thus become complementary to Wireshark. This is the Mac OS X release.
You can download it from the following link: https://packetstormsecurity.com/files/download/107582/ostinato-bin-osx-universal-0.5.dmg.gz
Source: https://packetstormsecurity.com/files/107582/Ostinato-Traffic-Generator-0.5-Mac-OS-X.html