Telnet

telnet - Benutzerschnistelle für das Telnet-Protokoll

Beschreibung

• Der Befehl telnet wird für die interaktive Kommunikation mit einem anderen Rechner mit Hilfe des Protokolls TELNET verwendet.
• Für Fernanmeldungen (remote login) sollte anstatt des vorliegenden Clients ein SSH-Client oder in einigen Fällen Varianten wie telnet-ssl oder Kerberos-Telnet-Clients vorgezogen werden. Der wichtigste Grund ist, dass diese Implementierung Benutzernamen und Passwort im Klartext austauscht.
• Andererseits ist das vorliegende Programm ausreichend für allgemeine Anwendungsfälle bei der Netzwerkdiagnose, wie beispielsweise Protokolltests von SMTP-Diensten, und kann sich so als praktisch erweisen.

The telnet command is used for interactive communication with another host using the TELNET protocol.

• It begins in command mode, where it prints a telnet prompt ("telnet> ").
• If telnet is invoked with a host argument, it performs an open command implicitly; see the description below.

Syntax

 $ telnet [-468ELadr] [-S tos] [-b address] [-e escapechar] [-l user] [-n tracefile] [host [port]]

Optionen

Aufgabe	Befehl
-4	Force IPv4 address resolution.
-6	Force IPv6 address resolution.
-8	Request 8-bit operation. This causes an attempt to negotiate the TELNET BINARY option for both input and output. By default telnet is not 8-bit clean.
-E	Disables the escape character functionality; that is, sets the escape character to ``no character.
-L	Specifies an 8-bit data path on output. This causes the TELNET BINARY option to be negotiated on just output.
-a	Attempt automatic login. Currently, this sends the user name via the USER variable of the NEW-ENVIRON option if supported by the remote system. The username is retrieved via getlogin(3).
-b address	Use bind(2) on the local socket to bind it to a specific local address.
-d	Sets the initial value of the debug toggle to TRUE.
-r	Emulate rlogin(1). In this mode, the default escape character is a tilde. Also, the interpretation of the escape character is changed: an escape character followed by a dot causes telnet to disconnect from the remote host. A ^Z instead of a dot suspends telnet, and a ^] (the default telnet escape character) generates a normal telnet prompt. These codes are accepted only at the beginning of a line.
-S tos	Sets the IP type-of-service (TOS) option for the telnet connection to the value tos.
-e escapechar	Sets the escape character to escapechar. If no character is supplied, no escape character will be used. Entering the escape character while connected causes telnet to drop to command mode.
-l user	Specify user as the user to log in as on the remote system. This is accomplished by sending the specified name as the USER environment variable, so it requires that the remote system support the TELNET NEW-ENVIRON option. This option implies the -a option, and may also be used with the open command.
-n tracefile	Opens tracefile for recording trace information. See the set tracefile command below.
host	Specifies a host to contact over the network.
port	Specifies a port number or service name to contact. If not specified, the telnet port (23) is used.

Umgebungsvariablen

• Telnet uses at least the HOME, SHELL, DISPLAY, and TERM environment variables.
• Other environment variables may be propagated to the other side via the TELNET NEW-ENVIRON option.

Konfiguration

Dateien

Datei	Beschreibung
/etc/telnetrc	global telnet startup values
~/.telnetrc	user customized telnet startup values

Testfragen

Testfrage 1

Antwort1

Testfrage 2

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Testfrage 3

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Testfrage 4

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Testfrage 5

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