How can i write port scanner in UDP fashion?

[f ben isaac]

I know how to write a port scanner over TCP - i should connect() to each port.
How to do it in connectionless fashion?

I tried to do sendto(), but i discovered all messages are sent normally and i receive no. of bytes sent. So its not a proper way to test whether port is open or not since sendto() always succeed....

Any idea?

am doing it for practicing...

[jsmith]

You will have to use ICMP Echo Requests and look for replies with the error "Destination port not found".