port detecter?

[cmk128]

Hi
My office computer is in a sub-net, and my home computer have a real
IP. I want to write a java programmer to detect which port is
blocked/un-block within the sub-net.
How can i open a socket that specify the port? not the destination
port, is the source computer port.


office computer (port 88) ---> my home computer (port 80)

!!! I can connect to my home computer's port 80, but i can't control
which port of office computer is used to connect to?


If really can't do it, how can i write a port scanner? My home computer
can't create a connection to my office computer because my office
computer is within a sub-network.

thanks
from Peter ([email protected])

 

[HK]

If really can't do it, how can i write a port scanner? My home computer
can't create a connection to my office computer because my office
computer is within a sub-network.

Since your message sounds like you are rather in need of
a port scanner than a programming exercise, I dare to
point you to nmap:

http://www.insecure.org/nmap/

Harald.