Other Networking Commands

In addition to ftp, which is used to transfer—copy—files from system to system, there are a number of other common networking commands. These commands work to help the connection among your computer and others on the same link. Generally, if you work at a site with multiple UNIX computers, these computers will be networked together, usually using the Ethernet network protocol. Your systems may also be networked with the worldwide Internet, which as you already know is a collection of connected networks. (Say that three times fast.)

Using the Rlogin Command

The rlogin command allows you to remotely login to another computer on your network (remember that if you’re on the Internet, you’re on a worldwide network). You must, of course, have a valid user account on any machine to which you want to login. To use rlogin, you need the name of the machine to login to. To login a machine named nicollet, you’d use a command line like the following:

     gilbert:/$ rlogin nicollet

     Password:

At the Password prompt, you may need to enter your password on machine nicollet, which may or may not be different from the password you use on your local machine. Once logged in, you’re computing on the remote machine and can run any standard UNIX command. You also logout the same way you normally logout:

     gilbert:/$ logout

     Connection closed.

     $

Note that after you logout from a remote machine, you’re back to the command prompt at your local machine. This tends to get confusing, so be careful.

The basic form of rlogin is:

     rlogin hostname

where hostname is the name of the machine to login.

Using the Telnet Command

The telnet command works much the same as rlogin does, allowing you to connect directly to a remote machine. Because the telnet command is considered part of the toolkit used by the Internet surfer, it’s actually gained in popularity over the years.

Telnet allows you either to run a command directly on a remote machine while displaying the results on your own or to run a specific command on a remote machine (many sites that allow Telnet put restrictions on what users can run, due to security concerns). With telnet, you only need to know the address of the machine you’re connecting to, such as sunsite.unc.edu, as illustrated by the following:

  gilbert:/$ telnet

  telnet> open sunsite.unc.edu

  Trying 198.86.40.81

  Connected

  *************** Welcome to SunSITE.unc.edu ***************

  SunSITE offers several public services via login. These include:



  NO MORE PUBLIC gopher login!

  Use lynx the simple WWW client to access gopher and Web areas

  For a simple WAIS client (over 500 databases),  login as swais

  For WAIS search of political databases,         login as politics

  For WAIS search of LINUX databases,             login as linux



  For a FTP session, ftp to sunsite.unc.edu. Then login as anonymous



  For more information about SunSITE, send mail to info@sunsite.unc.edu



  UNIX (R) System V Release 4.0 (calypso-2.oit.unc.edu)



  login: swais

In this case, sunsite.unc.edu offers a variety of services to the general computing public, here centering around WAIS databases. Other Telnet sites may not offer such a wide variety of services; a site like archie.rutgers.edu offers only archie searches.

Unfortunately, Linux does not offer archie yet, so you’ll need to use a public archie server to perform a search.

Sunsite.unc.edu is a public Internet site. If you’re using telnet within your corporation, the rules will be slightly different. Here, sunsite.unc.edu offers public access; you don’t need an account on sunsite.unc.edu, nor do you need a password. However, sunsite.unc.edu does put restrictions on what can be done by a visitor; for example, you can’t use the standard Linux command set and your options are limited to the login selections. For a private system, you’ll need an account on the remote system before you can login, and you may be subject to the same sorts of restrictions.