Re: Windows refusing connections

From: Thomas Roach <>
Date: Tue, 12 Jan 2010 13:32:47 -0500
Message-ID: <>

Did you look at the Windows firewall settings? You may need to go into that (in control panel) and allow ports 1521 and 1526. Also check for other "soft" firewalls on the box. To test connectivity, see if you can telnet to those ports from a remote box and then locally.

On Tue, Jan 12, 2010 at 1:25 PM, Jason Heinrich <>wrote:

> This is a bit obscure and I can't reproduce it at will, but I was wondering
> if anyone here has seen something similar. First the stats:
> Oracle EE Patch 26 (Oct09 CPU)
> Windows Server 2003 SP2, x64, patched to the mega-update MS released about
> the same time as the Oct09 CPU.
> On this particular server, after applying both the patches mentioned above
> at the end of October, my monitoring started reporting sporadic "ORA-12541:
> TNS:no listener" errors. I've also seen the same error occasionally when I
> do a lsnrctl status, but other clients don't seem to be affected. Also, the
> same patches were applied to other servers, and they don't have the same
> problem. Tracing revealed that something is blocking the connection.
> I've tried a few things to resolve this, but nothing has worked so far:
> - Added (QUEUESIZE=200) to the listener.ora
> - Added a second port to the listener for the monitoring.
> - Tried to balance incoming connections between the two ports. I still see
> the error on both ports.
> Oracle Support says the following: "From the error we see in the lsnrctl
> trace, we see that something is blocking the connection to port 1521, on TCP
> layer, not SqlNet. So, it must be something on the machine at physical layer
> that rejects this connection to port 1521 or 1526." The fact that this
> started after the Windows security patches were applied makes me suspicious
> of that, but I'm uncertain which patch would be the culprit or how to prove
> it, especially since other servers seem to be fine. Anybody else experience
> this?
> --
> Jason Heinrich

Thomas Roach

Received on Tue Jan 12 2010 - 12:32:47 CST

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