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System User's Guide: Communications and Networks

Host Emulation Applications

An emulator is a software application that allows your system to function as if you were using a different terminal or printer.

Several applications are available to allow your system to emulate other types of terminals. The following sections provide information on terminal or printer emulators:

Note: The bterm command emulates terminals in bidirectional (BIDI) mode.

Emulators Introduction

A terminal emulator connects to a host system to access data or applications. Some terminal emulators provide a facility to transfer files to and from the host. Others provide an application programming interface (API) to allow program-to-program communication and automation of host tasks.

A printer emulator allows the host either to print files on a local printer or store them in printable form to be printed or edited later.

TCP/IP Commands for Emulation

The Transmission Control Protocol/Internet Protocol (TCP/IP) (Chapter 3, Transmission Control Protocol/Internet Protocol (TCP/IP) Overview) software includes the telnet and rlogin commands, which allow you to connect to and access a remote TCP/IP system.

telnet Command: the telnet command allows a user to log in to a remote host by implementing the TELNET protocol. It is different from the rlogin command in that it is a trusted command. A trusted command is one that meets all security levels configured on your computer. Systems that require extra security should allow only trusted commands. Standards for trusted commands, processes, and programs are set and maintained by the U.S. Department of Defense.

Note: The tn command performs the same function as the telnet command.

rlogin Command: the rlogin command is similar to the telnet command in that both allow a local host to connect to a remote host. The only difference is that the rlogin command is considered a nontrusted command and can be disabled if your system needs extra security.

For more information about TCP/IP, refer to the Transmission Control Protocol/Internet Protocol (TCP/IP)Overview (Chapter 3, Transmission Control Protocol/Internet Protocol (TCP/IP) Overview).

BNU Commands for Emulation

The Basic Networking Utilities (BNU) (Chapter 4, Basic Networking Utilities (BNU) Overview) software includes the ct, cu, and tip commands, which allow you to connect to a remote system that uses this operating system.

ct The ct command enables a user on a remote terminal, such as a 3161, to communicate with a workstation over a telephone line. The user on the remote terminal can then log in and work on the workstation.

The ct command is similar to the cu command but not as flexible. For example, the user cannot issue commands on the local system while connected to a remote system through the ct command. However, the ct command does allow the user to instruct the ct command to continue dialing until the connection is established or to specify more than one telephone number at a time.

cu The cu command connects your workstation to another workstation connected to either a UNIX or non-UNIX system.

After the connection is established, a user can be logged in on both systems at the same time, executing commands on either one without dropping the BNU communication link. If the remote computer is also running under UNIX, the user can transfer ASCII files between the two systems. The cu command can also be used to connect multiple systems, and commands can then be executed on any of the connected systems.

tip The tip command connects your workstation to a remote system and enables you to work on the remote system as if logged in directly.

You can use the tip command to transfer files to and from the remote system. You can use scripting to record the conversations you have with the tip command.

Note: You must have a login on the remote system to use the tip command.

For more information about BNU, refer to Chapter 4, Basic Networking Utilities (BNU) Overview.

Asynchronous Terminal Emulation (ATE)

The Asynchronous Terminal Emulation (ATE) program enables your workstation to connect to most systems that support asynchronous terminals, including any system that supports RS-232C or RS-422A connections. ATE allows the remote system to communicate with your terminal either as an asynchronous display or as a DEC VT100 terminal.

ATE enables you to run commands on the remote system, send and receive files, and check the data integrity in the files transferred between systems. You can also use a capture file to record, or capture, incoming data from the remote system. ATE is menu-driven and uses subcommands.

When installed, ATE is accessible only to users who have been registered as a member of the UUCP group by a user with root authority.

For more information about ATE, refer to Asynchronous Terminal Emulation (ATE) Concepts (ATE Concepts).

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