Port scan is a process to look for open ports on a host , it is done by sending requests to a host of a range of server port addresses with the goal of finding active ports. It is used to determine services available on a remote machine.
A port scanner , an application like Nmap is used to probe a server or host for open ports.
Port scan is used for both identifying services and attack purposes.
Portsweep is to scan multiple hosts with a specifice port , such as port 1433 to look for SQL service.
Port Scan results are generalized into three categories :
Open or Accepted: The host replied indicating that a service is listening on the port.
Closed or Denied or Not Listening: The host sent a reply indicating that the port is closed and connections will be denied to the port.
Filtered, Dropped or Blocked: There was no reply from the host
Scan Types
TCP scanning
SYN scanning
UDP scanning
ACK scanning
Window scanning
FIN scanning
Some more unusual scan types exist.
X-mas and Null Scan
Protocol scan
Proxy scan
Idle scan
CatSCAN
ICMP scan
