Re: [PLUG] nmap and port forwarding questions

[Casey Bralla <MailList@nerdworld.org>]

On Wednesday 30 December 2009 9:41:57 am Eric wrote:
> I'm working on a new server behind a firewall that is controlled by a
> third party.
> The new server is running the latest RedHat (5.4) and iptables is turned
> off.
> 
> I cannot connect to the postgresql database on port 5432 on the server.
> There is port forwarding on the firewall that is supposed to forward to
> the database server but no one can connect to it from the outside.
> 
> When I scan with nmap from my workstation I get this:  (n1.n2.n3.n4 is
> the ip address)
> 
> nmap -p 5430-5434 -PN n1.n2.n3.n4
> 
> Starting Nmap 4.62 ( http://nmap.org ) at 2009-12-30 08:26 EST
> Interesting ports on host-nnnnnn.net (n1.n2.n3.n4):
> PORT     STATE    SERVICE
> 5430/tcp filtered unknown
> 5431/tcp filtered unknown
> 5432/tcp filtered postgresql
> 5433/tcp filtered unknown
> 5434/tcp filtered unknown
> 
> For comparison, this is the same scan but over the port range where ssh
> is running (port 13325):
> 
> nmap -p 13323-13327 -PN n1.n2.n3.n4
> 
> Starting Nmap 4.62 ( http://nmap.org ) at 2009-12-30 08:26 EST
> Interesting ports on host-nnnnnn.net (n1.n2.n3.n4):
> PORT      STATE    SERVICE
> 13323/tcp filtered unknown
> 13324/tcp filtered unknown
> 13325/tcp open     unknown
> 13326/tcp filtered unknown
> 13327/tcp filtered unknown
> 
> An internal scan shows the port 5432 as "open".
> 
> What does "filtered" mean?
> Shouldn't port 5432 be "open"?
> 
> 
> TIA:
> 
> Eric
> 


"Filtered" means just what you would think it would mean.  They are blocking 
access to port 5432, so this is undoubtedly why you can't connect.

Just because you have not activated a firewall on your server does not mean 
that some other firewall is active between you and that server.  I would 
discuss this with your server provider and ask for the firewall to be opened 
up for this port.  (I  caution that this may be a security problem, however.)



-- 


Casey Bralla

Chief Nerd in Residence
The NerdWorld Organisation

http://www.NerdWorld.org
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