A network lets computers communicate with each other, sharing files, email, and much more. Unix systems have been networked for more than 25 years, and Macintosh systems have always had networking as an integral part of the system design from the very first system released in 1984.
This chapter introduces Unix networking: remotely accessing your Mac from other computers and copying files between computers.
There may be times when you need to access your Mac, but you can’t get to the desk it’s sitting on. If you’re working on a different computer, you may not have the time or inclination to stop what you’re doing, walk over to your Mac, and log in (laziness may not be the only reason for this: perhaps someone else is using your Mac when you need to get on it or perhaps your Mac is miles away). Mac OS X’s file sharing (System Preferences → Sharing) can let you access your files, but there may be times you want to use the computer interactively, perhaps to move files around, search for a particular file, or perform a system maintenance task.
If you enable Remote Login under System Preferences → Sharing, you can access your Mac’s Unix shell from any networked computer that can run SSH (http://www.ssh.com), OpenSSH (http://www.openssh.org), or a compatible application such as PuTTY (a Windows implementation of SSH available at http://www.chiark.greenend.org.uk/~sgtatham/putty/). SSH and OpenSSH can be installed on many Unix systems, ...