> I am going to use NetBSD 1.5. on my computer as Bastion/Firewall.
> I need  to secure NetBSD as much as possible.
> Does anyone have really good links on how-to secure NetBSD, or general security URL's related to NetBSD somehow?
> Or Does anyone have any tips and advises?

yes. read manuals.

netbsd differs from other unices that it haven't anything enabled
by default. so it's secure by default and you could only "desecure" it ;)