Quote from: jojothehumanmonkey on May 08, 2021, 07:05:34 PM
so it this website wrong?
http://www.ipv6scanner.com/cgi-bin/main.py
OPEN An application is listening for connections on that port.
CLOSED No application listening on that port.
FILTERED The port is blocked by firewall or other network obstacle.
No, but there's often common misunderstanding on the scanning results.
Basically there are lots of scanning techniques that are used for fingerprinting the target machine: https://nmap.org/book/man-port-scanning-techniques.html
They rely on the design of TCP/IP stack of the target. In case of online scanners, the TCP SYN scan is commonly in use. What the non-firewalled OS does upon receiving SYN is that it responds with RST to indicate that there's no service listening on the particular port.