FIN port scan

FIN is the finish data packet.

Attacker => FIN => Target

case 1: port open
Error message by deamon
case 2: port closed
No response

The output is similar to the TCP and SYN scan.

Pros and cons :
Stealth : good stealth as no connection is established with the target host
Not accurate :The scan is not reliable with non Inix systems

Countermeasures :
This type of scan can be blocked using simple firewall or route rule that blocks all FIN packets from systems which have no connection

FIN scan using Nmap

nmap -SF -P 1-200 www.target.com