Applied Network Security

UDP scan

Up until this point, all of our scans have been for TCP ports. Some services and ports use UDP to communicate with the outside world. Our previous scan types (-sS and -sT) will not find UDP ports as they are only looking for TCP ports. Some services only run on UDP, such as NTP (port 123) and SNMP (port 161).

To find these ports and services, we need to do a UDP scan. We can do this with the -sU switch by typing nmap -sU 192.168.10.70:

As you can see, the UDP scan reveals ports and services not found with our TCP scans.