Question : Verify Ports between systems.

I have a remote computer connect to my network through the internet.  Until a few days ago it could authenticate fine now I seem to be having trouble.  Does anyone know of a tool, I can install on both ends to verify that the tcpip ports are open all the way through the internet.  I run Windows 2000 on both sides server on my side and professional on the other

Answer : Verify Ports between systems.

Port scanners can be used to check if a port is open - there are many port scanners out there.

I would recommend fscan by foundstone as it is a fast command line scanner.
So to check to see if a certain port is open you would use this syntax

>fscan -qp 5800 127.0.0.1

this example scans ip addy 127.0.0.1 for port 5800
(the -q option means dont ping first)

you could also use netcat (nc.exe) to check if a port is available
nc -v -w 2 -z 127.0.0.1 5800
-v = verbose
-w = timeout 2 secs
-z = scan mode
and the result would be port open or closed

:)