quote from http://www.linuxquestions.org/questions/linux-security-4/telneting-to-a-udp-port-353876/ UDP is a connectionless protocol which means it basically just sends packets out to the specified destination. TCP is connection-oriented which means it establishes a connection to the other end using the ‘3-way handshake’. So it makes sense to apply the ‘telnet’ paradigm to TCP – you make connection to a specific … Continue reading How to test a listening UDP port using nmap