Port blocking?

August 18, 2010 at 10:25:24
Specs: Windows XP
If 2 pc's are on a LAN and attached to the same hub where does port blocking take place? I need to get communication between them over 2939 for my devices to work but the IT guy says that nothing is being blocked. I loaded C-Ports on both pc and it shows nothing for 2939..and Telnet wont work between them either. Thanks. oh and the windows firewalls are off.

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#1
August 18, 2010 at 12:33:19
If 2 pc's are on a LAN and attached to the same hub where does port blocking take place?

First of all, I believe you mean "switch" not hub. Nobody uses hubs anymore. I suggest you quickly google and compare the two so you have a basic understanding of what each device is, what it does, and how they differ. This will give you an understanding of why nobody uses hubs anymore and you won't in the future refer to a switch as a hub. Yeah, I know this is a little "nit picky" but even though a Ford and a Chev are both automobiles, you don't call a Ford a Chevy right.

Having said that, I don't know of any switches that do "port blocking" in the sense you mean it.

I need to get communication between them over 2939 for my devices to work but the IT guy says that nothing is being blocked. I

While nobody is perfect, I suspect your IT guy is giving you the straight goods. What kind of devices are you talking about and why do they use 2939?

I loaded C-Ports on both pc and it shows nothing for 2939..

Ok, this confirms what your IT guy told you. So, you've ruled out "port blocking" so where does that leave you........with the devices you're trying to use, or the software that you use to interface with them.

Telnet wont work between them either.

Telnet uses port 23 by default, not 2939. Are you sure those PC's are setup to allow telnet connections? If they're windows based PC's to the best of my knowledge they do not accept telnet sessions by default. So unless you've fixed it so those PC's can accept an incoming telnet session, it only makes sense that telnet won't work.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#2
August 18, 2010 at 13:52:59
Curt,
Thanks for your response. Sorry about he whole hub/switch deal.
Will use switch in the future.
using Cports does allow me to see what ports a pc is listening on.
Comparing both pcs I saw that 42510 is open on both and I can telnet between each with that port.
However it doesn't explain why I can't use the port 2939 like I want to. Yes its proprietary. Between ECopy and Equitrac. You put key on the Ecopy server and configure it to use 2939. 2939 is an Equitrac port so it should be listening there already but it isn't listed in Cports.
I was just looking for a reason that these 2 pc's cant. Being internal to the network is there anything in the Firewall that may need to be set?

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#3
August 18, 2010 at 16:01:06
Ah never used cport. It's the same like netstat -anb in a command prompt window.
If port 2939 is not listed in CPort, there is no local service running, that listens on port 2939.

That means, you can have open as many ports as you like. If there is no local service (programs) listening to one of that ports, it doesn't care whether these ports are open or closed, because they are not accessable.

It's just like this:
If you're not at home to open someone the door, it doesn't care, how many people are ringing the bell, they can't get into your house.

The original poster should always write the last response !!!
Let us know, if the problem is solved !!!


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#4
August 19, 2010 at 05:17:15
X2 - What paulsep said!

If port 2939 is not listed in CPort, there is no local service running, that listens on port 2939.

So, what this tells me is, whichever piece of software you have that is supposed to be listening on 2939 for a connecion, isn't. Or at the very least, it's trying to, but it's being blocked. I never thought to ask you before but, are you running the built in Windows Firewall on either (or both) of these PC's? If yes, shut it off and then try again. A firewall would definitely block this, and likely the default telnet port as well.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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