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Old 04-26-2007, 03:19 AM   #1
Registered: Aug 2003
Location: Edinburgh
Distribution: Server: Gentoo2004; Desktop: Ubuntu
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nmap: state closed on SSH port. What does that mean?


I had trouble getting into my server with SSH. I did nmap on it and go the below:

iskmb@iskmweboffice:~$ nmap -P0 a.b.c.d

Starting nmap 3.81 ( ) at 2007-04-26 08:15 BST
Interesting ports on . (a.b.c.d):
(The 1660 ports scanned but not shown below are in state: filtered)
22/tcp closed ssh
8080/tcp open http-proxy
8443/tcp open https-alt

What does state "closed" mean? Any why would it happen?

Old 04-26-2007, 03:53 AM   #2
Registered: Aug 2006
Posts: 609

Rep: Reputation: 79
I will copy literally from the Nmap reference Guide:

The output from Nmap is a list of scanned targets, with supplemental information on each depending on the options used. Key among that information is the “interesting ports table”. That table lists the port number and protocol, service name, and state. The state is either open, filtered, closed, or unfiltered. Open means that an application on the target machine is listening for connections/packets on that port. Filtered means that a firewall, filter, or other network obstacle is blocking the port so that Nmap cannot tell whether it is open or closed. Closed ports have no application listening on them, though they could open up at any time. Ports are classified as unfiltered when they are responsive to Nmap's probes, but Nmap cannot determine whether they are open or closed. Nmap reports the state combinations open|filtered and closed|filtered when it cannot determine which of the two states describe a port. The port table may also include software version details when version detection has been requested. When an IP protocol scan is requested (-sO), Nmap provides information on supported IP protocols rather than listening ports.
Token from:

Your ssh is probably not running.

Check with:
ps aux | grep ssh

Are you doing this from the localhost?
First try on the host where ssh is running on:
ssh username@localhost

If this works, your firewall probably blocks it.


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