NMAP
NMAP is a free, open source tool for network discovery and security testing. NMAP will discover which TCP and UDP ports are open or responding. It will also determine which layer 3 services are supported by your device. ODVA has strict guidelines for open ports, and mandatory layer 3 services. For the NMAP procedure used by TSPs please see the Sample Test Report that comes with Conformance Test Software from ODVA.