OK picture this. I've been working all night long on a PowerPoint Presentation on my desktop at home. In the morning, I pick up my trusty iBook and go to the office ready for my presentation, but I find that I forgot to copy the file to the laptop!
I don't shutdown my desktop at home, and my internet connection is always on. I also allow SSH (secure shell) connections through my firewall, and my Mac has the "Remote Login" option ticked in the sharing prefs (which enables SSH). So I open up my laptop at work, connect to the office network, then open up Terminal and type:
% scp zed@192.9.200.1:/Users/zed/Documents/MySlides.ppt .Note that the above is all one line, and don't forget the fullstop on the end.
Basically, this command (scp = secure copy; type 'man scp' for more information) uses the SSH tunnel (encrypted) to make a connection to my system at home (192.9.200.1) and login as zed. It asks for my password and then downloads that file I specify. I have to know the path but I could ssh in first to check that out. The fullstop at the end says "save the file here," so that's where ever you are in the directory when you issue the command.
You can also run the command the other way around to copy a file from your local system to the remote:
% scp MySlides.ppt zed@192.9.200.1:/Users/zed/Documents/It's also worth noting that if your user names are the same on the remote system and the local system, then you do not need to type zed@192.9.200.1 but rather you can just type 192.9.200.1. Replace these numbers with your home machine's IP address, of course.
All the data transfered this way is encrypted and means that you do not have to run web servers or FTP servers which are not secure!

