thanks .unicorn....I´m working on it and I´ve read your 3 "steps" and also that thread started by Jessica.
I can login from my local LAN to Serv-U(v 4.0.0.4) and everything seems nice, I can upload and download...but the problem is when I try to access from the outside?!
I have a Netgear RT314 router/firewall, so the problem is, I guess, to config - forward the ports to my servbox. And the reference manual for this router could be better

but sooner or later I will find the solution.
Cheers
IB
