Other residents of the Application layer are TCP/IP's utilities. The TCP/IP utilities originally were developed around the Internet and early Unix networks. These utilities are now used to configure, manage, and troubleshoot TCP/IP networks throughout the world, and versions of these utilities are now available with Windows and other network operating systems.
This book classifies the TCP/IP utilities into four categories: connectivity utilities, file transfer and access utilities, remote access utilities, and Internet utilities. The Internet applications (shown in Table 7.1 and discussed in Hour 16, "How the Internet Works") are newer and less Unix-like than the other applications in Table 7.1, but they are similar in that they provide the user with access to information and resources across a TCP/IP network.
Table 7.1. TCP/IP Utilities
A Windows utility that displays TCP/IP configuration settings. (The Unix utility ifconfig is similar.)
A utility that tests for network connectivity.
A utility that lets you view (and possibly modify) the ARP cache of a local or remote computer. The ARP cache contains the physical address to IP address mappings. (See Hour 4, "The Internet Layer.")
A utility that traces the path of a datagram through the internetwork.
A utility that lets you view, add, or edit entries in a routing table. (See Hour 9, "Network Hardware.")
A utility that displays IP, UDP, TCP, and ICMP statistics.
A utility that displays statistics on NetBIOS and NBT.
A utility that returns the hostname of the local host.
File Transfer Utilities
A basic file transfer utility that uses TCP.
A basic file transfer utility that uses UDP. Tftp offers very little security and is used for tasks such as downloading code to network devices.
A simple remote file transfer utility.
A remote terminal utility.
A utility that runs commands on a remote computer through the rexecd daemon.
A utility that invokes the shell on a remote computer to execute a command.
A utility that displays user information.
Utilities that provide access to World Wide Web HTML content.
Utilities that connect with Internet newsgroups.
Utilities that provide a means of sending and receiving email.
A once-popular Internet utility that provides access to indexes of anonymous FTP sites. The World Wide Web and its search engines have reduced the importance of Archie.
A menu-based Internet information utility. Like Archie, Gopher looks old-fashioned next to the World Wide Web, and is no longer popular.
A utility that provides access to directories with personal contact information, similar to Internet white pages.