Checking if a port is listening

[Lucien via Digitalmars-d-learn]

Hello,

I want to know if a port of an ip address is listening, actually, 
I've this :
http://pastebin.com/pZhm0ujy
(checking port 22/ssh)
It works, but it took me ~10min to scan 30 addresses.

How can reduce the expiration delay ?