[jhb_airlines] Port problem

  • From: "Bones" <bones@xxxxxxx>
  • To: "JHB Email List" <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Sat, 31 Jul 2004 04:14:50 +0100


After a couple of fruitless hours trying to read up on port settings for
a network I decided to look at things from a different angle. I got a
possible lead from the MS query base when it said that if a program
opens a port on your machine then no other program can access that port.
I'd always been considering that your port was blocked by a firewall
setting and didn't consider it may already be in use.

Regardless of either there was a means described by MS on how to
determine a ports usage. The following is from their web page:

"The Netstat.exe utility has a new switch, the -o switch, that can
display the process identifier (ID) that is associated with each
connection. This information can be used to determine which process
(program) listens on a given port. For example, the netstat -ano command
can produce the following output: 

Proto    Local Address    Foreign Address    State        PID
TCP          Listening    888
If you use Task Manager, you can match the process ID that is listed to
a process name (program). This feature enables you to find the specific
port that a program currently uses. Because this specific port is in use
already by a program, another program is prevented from using that same

So, open up the command prompt on both your machines and type


This should bring up a list as shown above and, hopefully, you should
see the ATOC ports listed amongst them. I should add that you should be
running ATOC at the time you run NETSTAT.

Look at the PID numbers for all the lines containing the ATOC port
numbers. Hopefully these should all be the same. 
Now right click on the taskbar and open Task Manager. Go to the
Processes tab and you will see all the running processes together with
their PID's. If the PID column isn't showing then use View... Select
Columns to bring it up.
You can now compare the PID numbers you got from NETSTAT with the
process list in Task Manager to see which program is using the port.
Ideally it should be ATOC but if any firewall is trapping the port it
will show up here.


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