Nmap Scan Types and Port States

Vocabulary flashcards covering Nmap scan types, command flags, expected probe responses, and the six Nmap port states with their meanings.

SYN Scan (-sS)

An Nmap scan using command -sS where a SYN/ACK response indicates an Open port, an RST response indicates a Closed port, and no response indicates a Filtered port.

Connect Scan (-sT)

An Nmap scan using command -sT where a connection that succeeds indicates the port status is Open.

ACK Scan (-sA)

An Nmap scan using command -sA where an RST response indicates an Unfiltered port, and no response indicates a Filtered port.

FIN Scan (-sF)

An Nmap scan using command -sF where an RST response indicates a Closed port, and no response indicates an Open|Filtered port state.

NULL Scan (-sN)

An Nmap scan using command -sN where an RST response indicates a Closed port, and no response indicates an Open|Filtered port state.

Xmas Scan (-sX)

An Nmap scan using command -sX where receiving no response indicates an Open|Filtered port state.

UDP Scan (-sU)

An Nmap scan using command -sU where a UDP response indicates Open, ICMP Type 3, Code 3 indicates Closed, and no response indicates Open|Filtered.

ICMP Type 3, Code 3

The response received during a UDP scan (-sU) that indicates the port status is Closed.

Open (Nmap Port State)

An Nmap port state meaning an application accepts connections or responds on the port.

Closed (Nmap Port State)

An Nmap port state meaning the port is reachable, but no application accepts connections there.

Filtered (Nmap Port State)

An Nmap port state meaning Nmap cannot determine the state because of filtering or lack of responses.

Unfiltered (Nmap Port State)

An Nmap port state meaning the port is reachable, but an ACK scan cannot say whether it is open or closed.

Open|Filtered (Nmap Port State)

An Nmap port state meaning the port could be open or filtered.

Closed|Filtered (Nmap Port State)

An Nmap port state meaning the port could be closed or filtered; seen with certain scan types such as IP ID idle scanning.