I've made an scan to one single IP with nmap and it reports that the port 65301 is opened, and even it detects that it's maybe the service pcanywhere.
sudo nmap -p 65000-65535 -sV x.x.x.x Starting Nmap 6.00 ( http://nmap.org ) at 2015-06-04 22:43 CEST Nmap scan report for x.x.x.x Host is up (0.96s latency). Not shown: 336 closed ports PORT STATE SERVICE VERSION ... 65003/tcp open unknown 65301/tcp open pcanywhere? 65308/tcp open unknown ...
But when I try to establish a connection to that port with telnet, it just refuses the connection:
$ telnet x.x.x.x 65301 Trying x.x.x. ... telnet: Unable to connect to remote host: Connection refused
What may be the cause of the "connection refused": has nmap returned a false detection and the port isn't really opened? Or maybe there is some additional restriction that makes telnet not being able to connect though the port is opened?
The same happens with the other port with service "unknown", but that fact that thugh it has detected a possible service (pcanywhere) but telnet get connected intrigues me.
UPDATE: I attach the results of the execution of the command proposed by StackzOfZtuff, it detects the port as closed, which I think it's the normal behaviour (moreover the first command now reports the port as closed now):
$ sudo nmap -vv --packet-trace -p 65301 -sV x.x.x.x ... Initiating SYN Stealth Scan at 10:24 Scanning x.x.x.x [1 port] SENT (0.1877s) TCP y.y.y.y:53502 > x.x.x.x:65301 S ttl=53 id=3258 iplen=44 seq=3444593130 win=1024 <mss 1460> RCVD (0.1881s) TCP x.x.x.x:36876 > y.y.y.y:41094 RA ttl=255 id=62429 iplen=40 seq=0 win=0 RCVD (0.2064s) TCP x.x.x.x:21053 > y.y.y.y:41094 RA ttl=255 id=62430 iplen=40 seq=0 win=0 RCVD (0.2084s) TCP x.x.x.x:42352 > y.y.y.y:41094 RA ttl=255 id=62431 iplen=40 seq=0 win=0 RCVD (0.2110s) TCP x.x.x.x:4036 > y.y.y.y:41094 RA ttl=255 id=62432 iplen=40 seq=0 win=0 RCVD (0.2308s) TCP x.x.x.x:30952 > y.y.y.y:41094 RA ttl=255 id=62433 iplen=40 seq=0 win=0 RCVD (0.2352s) TCP x.x.x.x:65301 > y.y.y.y:53502 RA ttl=255 id=62434 iplen=40 seq=0 win=0 Completed SYN Stealth Scan at 10:24, 0.05s elapsed (1 total ports) Initiating Service scan at 10:24 NSE: Script scanning x.x.x.x. NSE: Starting runlevel 1 (of 1) scan. Nmap scan report for x.x.x.x Host is up (0.0061s latency). Scanned at 2015-06-06 10:24:17 CEST for 0s PORT STATE SERVICE VERSION 65301/tcp closed pcanywhere