Diagnostic
Obtaining used port numbers

You can obtain used port numbers using netstat.exe program (shipped with windows).

Start "DOS Command Prompt" using "Start Menu/Programs/Command Prompt". When you type in DOS window netstat -na and then press Enter, you will get list of all opened TCP/IP ports. You can use command "more" to stop when your listing contains to much lines (netstat -na | more).

Each line of netstat's listing contains these information:

• Protocol type - it can be TCP or UDP. Two sockets can use the same port number when they use different protocols.
• Local Address - local IP address which is used. In most cases it is 0.0.0.0 (any = not bound to the specific IP address. It can accept connection from any PC's interface). When IP address is specified then only connection from interface with the same IP address are accepted.
  Local Address field contains port number which is used to accept connection or receive UDP data.
• Foreign Address - address of PC on remote side. It will be displayed when connection is established.
• State - state of socket. You can see this states:
  LISTENING - socket waits for connection (or data in case of UDP socket)
  ESTABLISHED - connection to the remote side is established
  CLOSE_WAIT, TIME_WAIT - socket waits for connection close or other type of negotiation.

To determine whether desired port number is already in use you must check Local Address field on all lines.

Example:

TCP 0.0.0.0:25 0.0.0.0:0 LISTENING
Some application which uses port 25 (SMTP server port) is running. To use P+'s mail server you must at first stop this application.

Notice:
When finding used (or free) port number stop Proxy+ first.