2.3 NETWORKING
Networks are a key component of Linux operating systems. Each computer on a network may have a name, such as 'claymore.engineer.gvsu.edu', but each computer must have a number, such as '148.61.104.215'. You can log into other Linux and Unix machines with commands such as `telnet claymore.engineer.gvsu.edu', 'telnet 148.61.104.215' or `rlogin claymore.engineer.gvsu.edu'. This allows you to sit at one machine, and use many others, even around the world.
You can also access other computers with public access directories using the `ftp' command. For example try `ftp ftp4.netscape.com'. This will connect you to a computer some place in the U.S. When it asks you for your `login name' type `anonymous'. When it asks for a `password', enter your name. You may now move around using ls, pwd, cd, etc. If you want to get a file from some directory, type `binary', then type `get filename', or 'get filenames'. `quit' ends everything. If you log into a machine with FTP and you have write permissions you can also write files to the machine using 'put filename' or 'mput filenames'. If you use FTP to log into a computer that you have account on you will be able to move outside of the limited ftp directories.
2.3.1 Security
Security is not a significant problem for a computer that is not connected to a network, and passwords will protect it from `honest thieves'. When connected to a network there is potential for security problems. These problems become more serious when the computer is connected to the network 24 hours a day. General rules to keep a computer safe (this applies to non-Linux computers also) are:
keep user passwords safe - these can be the start of a security breach
protect the root password - loosing this throws the system wide open
shut down unneeded programs - network programs sometime have bugs that open doors
apply patches - software updates help close security holes
