I'm testing some vulnerabilities on a machine which has the port 22333 opened (it's used as the ssh port, and I can connect to it without any problem and the telned command get connected):
$ telnet x.x.x.x 22333 Trying x.x.x.x... Connected to x.x.x.x. Escape character is '^]'. SSH-2.0-OpenSSH_6.0p1 Debian-4+deb7u2
But when I use nmap against that machine, it doesn't detect that port to be listened to:
$ sudo nmap -p 22000-23000 -sT x.x.x.x Starting Nmap 6.00 ( http://nmap.org ) at 2015-06-03 19:54 CEST Nmap scan report for x.x.x.x Host is up (0.00014s latency). All 1001 scanned ports on x.x.x.x are filtered Nmap done: 1 IP address (1 host up) scanned in 21.50 seconds
Any clue about why nmap doesn't detect the port 22333?