Networking is as ubiquitous today as computers themselves. Few computers operate in isolation, but are part of networks of computers within an organization (intranet) or throughout the world (Internet). (We will use the terms network connection and Internet interchangeably throughout this chapter.) Underneath the hood are many types of processors, running a variety of operating systems.

The UNIX user, often even more than the OpenVMS user, performs a variety of network-related tasks. This chapter identifies those tasks and describes the commands required to perform them. Unfortunately, this entails more than the relatively simple matter of defining a single command for each task: The commands vary according to the type of connection existing between the UNIX computers, the type of access permitted by the system administrator of each computer, and the type of access permitted by the owner of each remote account you might want to access. For the purposes of this discussion, we consider two types of connection:

• Network: a fast, continuous connection using dedicated communication

• Modem: a slow, intermittent connection using telephone lines, in which tasks are often queued for transmission by means of the UNIX to UNIX CoPy (UUCP) utility

To further complicate the situation, the commands used in network communications are subdivided according to whether the connection is to a UNIX trusted host or nontrusted host. The OpenVMS analog to a UNIX trusted host...