Network map using nmap
$ nmap -O -sS -p 20-23,3300,80,443 ... Interesting ports on localhost (127.0.0.1): PORT STATE SERVICE 20/tcp closed ftp-data 21/tcp closed ftp 22/tcp closed ssh 23/tcp closed telnet 80/tcp open http 443/tcp closed https 3300/tcp open unknown Device type: general purpose Running: Linux 2.6.X OS details: Linux 2.6.17 - 2.6.25 Network Distance: 0 hops ... |
I configured sshd to listen on port 3300, but nmap can’t resolve the type of service in the above sample. (It is found to be open but unknown service)