Upgrading and Repairing Networks

Other Services and Applications Built on the TCP/IP Suite

You'll find many services in older RFC documents referring to protocols or utilities that once served an important purposefor example, the ARCHIE and WAIS utilities. However, as the Internet has made obsolete many older protocols and utilities, it has provided a hotbed for the development of new utilities, services, and applications. Many of these services are no longer needed or used, or are used in limited locations because more improved methods have generally replaced them.

Other protocols, such as the Simple Mail Transfer Protocol (SMTP) and the Simple Network Management Protocol (SNMP), are also very popular and useful protocols for providing application support on the network. However, these protocols are not as limited in their scope as the "utilities" discussed in this chapter. SNMP is discussed in Chapter 49, "Network Testing and Analysis Tools." SMTP and other Internet email protocols are covered in Chapter 26, "Internet Mail Protocols: POP3, SMTP, and IMAP."

Secure Network Services

As pointed out several times in this chapter, using some of the standard TCP/IP utilities that have been developed over many years can have security implications, especially now that most businesses are connecting to the Internet. The matters of user authentication and data encryption become more important when you expose your network to the world. Fortunately, as with most security issues, a need generally leads to someone coming up with a solution. In this section, we'll look at some more utilities that perform tasks similar to those already discussed, but in a more secure manner.

The Secure Shell (SSH) is the name given to a protocol that enables you to replace rsh, rlogin, rcp, telnet, rexec, rcp, and ftp with a more secure application. You can visit a Web site devoted to these utilities at www.ssh.org. Here you can find out about the specifications for the protocols, mailing lists, patches, and places to download the utilities for your system. Although there are no Request for Comments documents yet for SSH, several Internet drafts are available at the Web site that describe everything from authentication to transport protocols.

SSH provides you with complementary commands for the utilities listed in the preceding paragraph. For example, instead of using the ftp command, you would use the sftp command. The same goes for the other utilities.

Secure Shell utilities can use various encryption methods for both authentication and encryption of the data sent across the network. Because different software houses may implement the SSH protocol a little differently, you might want to consider checking which ciphers are used by a particular product.