Chapter 25. Basic TCP/IP Services and Applications
SOME OF THE MAIN TOPICS IN THIS CHAPTER ARE
The File Transfer Protocol (FTP) 404 The Telnet Protocol 419 Using Telnet and FTP with a Firewall 424 The R-Utilities 425 The Finger Utility 431 Other Services and Applications Built on the TCP/IP Suite 433
In the preceding chapter, it was mentioned that TCP/IP usually refers not just to the two protocols represented by its acronym (the Transmission Control Protocol and the Internet Protocol), but also to other related protocols, services, and applications that were developed to work together. These are referred to as the TCP/IP protocol suite. A wide range of services and applications have been developed to work with TCP/IP, and most implementations contain a standard set of these, which are the subject of this chapter. In addition to services and applications, other protocols have evolved along the way as the Internet has grown, such as the Simple Mail Transfer Protocol (SMTP), discussed in the next chapter, which makes global email possible.
This chapter deals with the TCP/IP suite of utilities that are generally used by end users, and the protocols that these utilities use to communicate.
| Troubleshooting utilities, such as Ping and Traceroute, among others, are covered in Chapter 27, "Troubleshooting Tools for TCP/IP Networks." |
Because you've already read about how protocols within the TCP/IP protocol suites get data from one point to another, it's time to look at some of the protocols and applications you can use on a network. In this chapter you will see examples from various operating systems, including Unix, Linux, and Windows.
For some of the more important applications, such as FTP and telnet, we'll look closely at the protocol itself and the messages that are exchanged between client and server. These are the actual protocol commands that a particular utility uses to communicate with its counterpart. These low-level message or command exchanges can be useful when you are troubleshooting these applications using a protocol analyzer.
The sample syntaxes for commands found in this chapter are meant to show you that it's a good thing help files (or man pages) were invented. The difference in a command from one system to another can vary greatly.
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