[Twisted-Python] Porting my Win32 Twisted to Linux Twisted

[Simon Pickles]

Okay, my small problem is probably not down to twisted, more likely the 
problem resides somewhere between my seat and the keyboard. Anyway I 
hope one of you more experienced linux/Twisted users can shed some light.

I've built some small Twisted-Python client/server applications on 
Win32. Now I've finally made the break and moved to Ubuntu!

Its very impressive, but I have a few inevitable problems.

I have a server listening on localhost:7001, and a client trying to 
connect (local too). The client doesn't see the server, and keeps making 
connection attempts.

When I run System>Network Tools>Portscan on localhost, I can see port 
7001 is open with a service called 'afs3-callback'.

The odd thing is, once I have run the Portscan, my client suddenly sees 
the server and connects! Am I neglecting to do anything before running 
my python server, like open the port?

Why does Portscan seem to open the port for me?

Many thanks for your help and advice.

S