Okay this is practically not even a Linux question, it just so happens that the systems involved are Linux.
I've just moved into university and I want to use scp to get my old files from my box at home. I was going to use scp to copy a tar.gz of the files I want, but my old box is on a network within my house.
So what is the convention (I assume that this hasn't anything to do with the OS involved... just an internet thing) for IP addresses within a network? I know the computer's IP on the network, and I know the external IP... I really don't know anything about networking though. Help?
Thanks in advance

So you have a router?

If I interpeted that post corretly, you have a PC ascting as a router and then a home network behind it. You want to get to a computer on the other side of the router.

If that was right, then you need to look into port forwarding.

If not, please more information to describe the problem...

I have two computers connected to a router and the router conected directly to the internet. I want to access one of the computers connected to the router from my computer here at university that is connected to their netowork.
Thanks again.

Do you simply want to ssh into the box? ie: work on a console? Or do you want GUI access? if gui: you'll want to look into VNC
for ssh: install and run sshd nd enable port forwarding on your router
for VNC: install and run vncserver and enable port forwarding on the router

I think what he's looking into is more like an FTP style access... is this the case? if so.. you need to set up ftp access on the other box... before you can get into it to get any files... then set port forwarding in that router to point to the internal IP of the box you want access to... then you can use an ftp client on the outside to access the outside IP address of the home network... and it should automatically forward you to the specified computer....

so what how do i enable port forwarding? i found the page that correspnds to that on my router settings. the options are:

ext ports (blank to blank)
protocol TCP and protocol UDP (checkboxes)
IP address
and enable (another checkbox)

i assume that i plug in the IP of the machine that i want to acces, check one or both of the protocols, check enable, and also set ports. what ports do i want to select?

thanks again

If you want to use scp you'll have to forward port 22 (ssh -- scp works over ssh). So in your router configuration, tell it to forward port 22 to the internal IP of the machine that you want to ssh to.

thanks