How to install and use Portbunny
PortBunny can be found here:

PortBunny is a Linux-kernel-based port-scanner created by Recurity Labs. Its aim is to provide a reliable and fast TCP-SYN-port-scanner which performs sophisticated timing based on the use of so called "trigger"-packets. The port-scan is performed in 2 steps: First the scanner tries to find packets, to which the target responds ("triggers"). Second, the actual port-scan is performed. During the scan, the triggers, which were found in the first scanning-phase, are used to determine the optimal speed at which the target may be scanned.