UDP Scanning

UDP Scanning

Scanning for active UDP ports is very difficult to perform reliably. This
is due to the fact that UDP is a connectionless protocol, and there is no
reliable indication whether or not a destination port has received the
packets sent.

There are 3 primary methods used to scan for listening / open UDP
ports:
• Sending data to a UDP port, and awaiting a response from that port.
• UDP ICMP port unreachable scanning. Sending data to a UDP port,
and waiting for an ICMP port unreachable message. An ICMP port
unreachable indicates that the port is NOT active.
• UDP recvfrom() and write() scanning.