Jim, I'd like to verify I have everything correct:
1) You want a low power use storage device network accessible from both internal and external sources to your network.
2) You want to use the FTP protocol (since you're on a mac, I assume cyberduck, or finder etc. in a GUI form) to access files there.
3) You do not need fancy and neat functions to go along with your NAS device, just FTP.
4) You run Macs and don't want your home computer to be on 24/7 (hence this device.)
About right?
So the steps I see are as follows:
1) Determine the device to purchase or build using old computer equipment.
This step is where we're at. As a side note, there are online services like MobilMe etc. that cut down on whether you need this hardware at all. I am going to assume that you prefer your data to be on your own hardware and not out in the cloud, or you would have checked out online storage services. Just wanted to mention them. They don't take any changes to your network.
2) Set up said device on your internal network and make it work.
This step will probably be the most time consuming. I would like to give some tips for this. You shouldn't use FTP. You should use SFTP, SCP or FTPS. The difference is a layer of security. Internally on your own network it wouldn't matter but since this is also going to face the world and be used over open internet, it's probably good to have your sessions encrypted with SSL so you don't broadcast your passwords in clear text across the internet. That said, most purchased NAS devices support this, and every one I know of that you can homebrew can be set up with this.
If you purchase:
Bring the device home, read the instructions, and plug it into your network. There will be a web page accessible at the ip address it is given for configuration. These steps will be fairly straight forward. The biggest trick is figuring out which address it was assigned internally to your network, and then making that a static IP address. This is done in your DHCP server which is most likely also your DSL modem. For that, you would also navigate in your web browser to the IP of your DSL modem, log in with whatever credentials you have in place, and change the DHCP service for your NAS device by assigning a static IP address to it. This generally is done in a section called "DHCP Reservations" or whatnot. Assigning this static IP will be based on the MAC address of the network card in your storage device. That should auto populate in the table showing the DHCP assignments on your modem. Here is a link to help you figure out how to configure your DSL modem:
http://portforward.com/
The above steps will require questions, feel free to ask them here. GreNME and I are happy to help (despite being pedantic prats from time to time.)
Once that is done, you need to tell your DSL modem to forward the ports for your service from the outside world to your NAS device. Here is where I am going to suggest a multitude of things to help stop johnny script-kiddy from owning your files.
1) The port facing the outside world should not be the standard port. Make it something up in the 30,000 range. I have several ports facing the world on my home machine and only when I absolutely have to do I run them on the standard settings. My SSH port is in the 20,000 range. This is a number high enough that standard scripted scans don't bother to search that range.
2)
Use strong passwords. I'm serious. This is the easiest way to get owned. Your password should be a minimum of 12-16 characters and use upper case, lower case, numbers and symbols. Preferably this shouldn't be dictionary words, but randomized sequences.
If you want to build this device out of existing hardware not currently used, or set up a service on your mac, that's another ball of wax that shares many of the steps above, but has more info you'll need.
Does that help?
