Port 25 Open, all computers are ok, but one.

I have a problem with Port 25 on one computer on the network. Case: corporate LAN, Windows 2000 Clients, and W2K Servers, Port 25 Open.
I have a small smtp utility for a specific task ('Advanced SMTP'), and it works on all computers, but on one it fails. Besides this, the computer is working great, it's the latest-fasted HP, configured the same way as the others.
Do you know what's causing this, and how to 'open' Port 25 (or fix it the problem other way)?
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stevenlewisConnect With a Mentor Commented:
not built in the os, but firewalls (XP has a built in one, but not 2000), a lot of AV products have one built in, as does (as mentioned above) the cisco vpn client
you can d/l msconfig for w2k here
then go tot he startup tab, and uncheck all but systray and explorer (if listed) and reboot and test, could be some third party app blocking it
also any errors in event viewer?
suspect the anti virus, or some other firewall (like the cisco vpn client has one built in)
ports open when an app needs to listen to it, no app listening, the port is closed
run netstat -a and netstat -an from a prompt on the machine, and check to see if it's listening (assume this is also a w2k box?)
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At a guess I'd say you have spyware or a virus that is keeping that port open.  Download this program: http://www.snapfiles.com/get/netmon.html

It will show all the open ports on your machine and which program/process is running it.  It should show you if the machine is already using port 25.

Good luck.
athanasius296Author Commented:
Thank you for your tips.
netsat shows many ports, but not 25. Port 25 shows up, when I start my 'Advanced smpt' program, but disappears when I close it.
I scanned for viruses (unlikely - we have very strong AV system), and spywares (didn't find any). So, the computer is clean, but still cannot use Port 25. Do you know if there's a way to disable Port 25 within Windows itself (some kind of OS configuration - yes, it's W2K Pro)?
>>'Advanced smpt' program, but disappears when I close it.
this is how it should work, again, the port will only be open when an app needs it (in this case your advanced smpt app. If the app isn't running, the port won't be open, so you need to have it running, and then from another machine run a port scanner and scan the ports on the problem machine to see if port 25 is open (while the app is running)
athanasius296Author Commented:
I know that port will only be open when an app needs it. The problem with my computer is that it properly shows, that the Port 25 opens when I start 'Advanced smtp', and closes Port 25 when I exit the program - but I can't use the Program!
This program has a built-in 'Tester', which checks for opened Port 25, and the test fails.
Again, it happenes on one computer only, so my question is if there's something in OS (some kind of setting) which prevents to use Port 25.
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