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After telnet successfully connects to the remote system, the login information is displayed and the system prompts you for your login ID and password. Assuming that you have a valid username and password, you successfully log in and can now work interactively on the remote system.
The following is an example of a telnet session from a Linux computer that connects to a Linux computer:
$ telnet server.somewhere.com Trying 127.0.0.1... Connected to server.somewhere.com. Escape character is '^]'. "Red Hat Linux release 4.0 (Colgate) kernel 2.0.18 on an I486 login: bubba Password: password Last login: Mon Nov 11 20:50:43 from localhost Linux 2.0.6. (Posix). server:~$ server:~$ logout Connection closed by foreign host. $
When you’re finished with the remote session, be sure to log out. telnet then reports that the remote session is closed, and you return to your local shell prompt.
File Transfer Protocol (FTP) is a simple and effective means of transferring files between computers that are connected on a TCP/IP network. FTP allows users to transfer ASCII and binary files.
During an FTP session, you connect to another computer by using the FTP client program. From this point, you can move up and down through the directory tree, list directory contents, copy files from the remote computer to your computer, and transfer files from your computer to the remote system. Normal file protections apply; you can’t get or put a file on the remote system if you don’t have the proper permissions for that file.
To use FTP to transfer files, you must know a valid username and password on the remote computer. This username/password combination is used to validate your FTP session and to determine what access you have to files for transfer. Also, you obviously need to know the name of the computer with which you want to conduct an FTP session.
You should be aware that FTP clients have different command sets, depending on the operating system in question. This chapter covers the Linux FTP client; however, when you start an FTP session with a remote computer, the commands that the remote system expects might be different. It’s rare for FTP systems to be completely incompatible with each other. Typically, the commands that you normally use are either slightly different or unavailable.
Due to the explosive growth of the Internet, many organizations have made huge repositories of information available via FTP. These FTP sites have everything from text files to software of every conceivable type available. But how do you access this enormous storehouse of data if you don’t have an account on the remote computer? Do you need to get an account on every FTP site in order to access these files?
In short, the answer is no. A common convention on the Internet allows guest FTP access to file repositories so that users can transfer files. This guest access is referred to as anonymous FTP. To use anonymous FTP, you start an FTP session to the remote system and use the username of anonymous and your e-mail address as the password. For example, in the following sample, the user named smith on linux.somewhere.com wants to initiate an FTP session with a common FTP site:
$ ftp ftp.uu.net ftp.uu.net (login:smith): anonymous Password: smith@linux.somewhere.com
NOTE: Many sites don’t allow anonymous FTP. Allowing guest users to connect to your computer does involve some risk. In cases where anonymous FTP isn’t allowed, the ftp command fails with a message similar to Login failed - User “anonymous” unknown. Sites that do permit anonymous FTP typically place the user in a restricted directory tree with read-only access. If you’re allowed to place files on the remote computer, you usually can put them in only one directory.
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