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Old 08-20-2008, 03:21 PM   #1
LQ Newbie
Registered: Mar 2008
Posts: 21

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need explanation about nmap and how to open a port

OS: Redhat 3, update 7
Java 1.5.0_05

I have a Java server program that is running and listening on port 3899 of machine B. On machine B, netstat -an|grep 3899

tcp 0 0* LISTEN

However, on machine B, nmap -v localhost shows
Starting nmap V. 3.00 ( )
Host localhost.localdomain ( appears to be up ... good.
Initiating SYN Stealth Scan against localhost.localdomain (
Adding open port 8082/tcp
Adding open port 22/tcp
Adding open port 113/tcp
Adding open port 389/tcp
Adding open port 8009/tcp
Adding open port 6000/tcp
Adding open port 80/tcp
Adding open port 111/tcp
Adding open port 631/tcp
The SYN Stealth Scan took 2 seconds to scan 1601 ports.
Interesting ports on localhost.localdomain (
(The 1592 ports scanned but not shown below are in state: closed)
Port State Service
22/tcp open ssh
80/tcp open http
111/tcp open sunrpc
113/tcp open auth
389/tcp open ldap
631/tcp open ipp
6000/tcp open X11
8009/tcp open ajp13
8082/tcp open blackice-alerts

My question is:

What do I need to do so that port 3899 will show up in the nmap list above as OPEN.

I tried iptables -I INPUT -p tcp --dport 3899 -j ACCEPT with no success.

I am trying to troubleshoot a Linux problem in which I cannot use a client to run this program remotely from a different server, machine A. The connection is always refused. Note that on two Windows machines, things run successfully.

redhat-configure-securitylevel shows that the firewall is enabled. I tried disabling with no success.

Any suggestions for troubleshooting this are appreciated. I am out of ideas.

Last edited by craftereric; 08-20-2008 at 03:28 PM.
Old 08-20-2008, 08:46 PM   #2
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Registered: Jul 2003
Location: Los Angeles
Distribution: Ubuntu
Posts: 9,870

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I think port 3899 isn't one of the ports it scans by default.

Try telling nmap that you wish to scan that port specifically:
nmap -v localhost -p 3899

Last edited by win32sux; 08-20-2008 at 08:47 PM.
Old 08-21-2008, 07:39 AM   #3
LQ Newbie
Registered: Mar 2008
Posts: 21

Original Poster
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follow-up question

Thanks for the response. You were correct. Apparrently 3899 is not scanned automatically.

nmap -v localhost -p 3899 shows:
Port State Service
3899/tcp open unknown

which is what I want on machine B.

Follow-up question(s):
I need to be able to remotely execute this process from a different machine A. In the windows, I can test if the remote invocation will work by executing telnet <machine B IP> 3899 from machine A.

For Linux, the command fails with telnet: Unable to connect to remote host: Connection refused. Therefore, my remote invocation also fails.

What needs to be done on machine A for the remote invocation to work. I tried the following on A with no luck:

iptables -I INPUT -p tcp --dport 3899 -j ACCEPT and
iptables -I FORWARD -p tcp --dport 3899 -j ACCEPT

On machine A, nmap -v localhost -p 3899 does not show anything because there is no service.

An explanation of what I need to do to get this working is appreciated.


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