telnet.1 (2010 09)

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telnet(1) telnet(1)

NAME

telnet - user interface to the TELNET protocol

SYNOPSIS

telnet [[options ] host [ port ]]

DESCRIPTION

telnet is used to communicate with another host using the TELNET protocol. If

telnet is invoked

without arguments, it enters command mode, indicated by its prompt (

telnet>). In this mode, it

accepts and executes the commands listed below. If

telnet is invoked with arguments, it performs an

open command (see below) with those arguments.

Once a connection has been opened,

telnet enters an input mode. The input mode will be either "char-

acter at a time" or "line by line" , depending on what the remote system supports.

In "character at a time" mode, most text typed is immediately sent to the remote host for processing.

In "line by line" mode, all text is echoed locally, and (normally) only completed lines are sent to the

remote host. The "local echo character" (initially

ˆE) can be used to turn-off and turn-on the local echo

(this would mostly be used to enter passwords without the password being echoed).

In either mode, if the

localchars toggle is TRUE (the default in line mode; see below), the user’s

quit and intr characters are trapped locally, and sent as TELNET protocol sequences to the remote

side. There are options (see toggle autoflush and toggle autosynch below) that cause this

action to ﬂush subsequent output to the terminal (until the remote host acknowledges the TELNET

sequence) and ﬂush previous terminal input (in the case of quit and intr).

While connected to a remote host,

telnet command mode can be entered by typing the telnet

"escape character" (initially

ˆ]). When in command mode, the normal terminal editing conventions are

available.

telnet supports 8-bit characters when communicating with the server on the remote host. To use

eight-bit characters you may need to reconﬁgure your terminal or the remote host appropriately (see

stty (1)). Furthermore, you may have to use the

binary toggle to enable an 8-bit data stream between

telnet and the remote host.

Note: Some remote hosts may not provide the necessary support for eight-bit characters.

If, at any time,

telnet is unable to read from or write to the server over the connection, the message

Connection closed by foreign host. is printed on standard error. telnet then exits with

a value of 1.

telnet supports the TAC User ID (also known as the TAC Access Control System, or TACACS User ID)

option. Enabling the option on a host server allows the user to telnet into that host without being

prompted for a second login sequence. The TAC User ID option uses the same security mechanism as

rlogin for authorizing access by remote hosts and users. The system administrator must enable the

(telnetd) option only on systems, which are designated as participating hosts. The system administrator

must also assign to each user of TAC User ID the very same UID on every system for which he is allowed

to use the feature. See the telnetd (1M) manpage and the HP-UX System Administrator’s Guide .

Options

The following

telnet options are available:

-8 Enable cs8 (8 bit transfer) on local tty.

-e c Set the telnet command mode escape character to be ˆc instead of its default value of ˆ].

-l Disable the TAC User ID option if enabled on the client, to cause the user to be prompted for

Kerberos-Speciﬁc Options

By default, or by use of the

-a or the -l option, the Kerberos version of telnet behaves as a client

which supports authentication based on Kerberos V5. As a Kerberos client, telnet will authenticate

and authorize the user to access the remote system. See the sis (5) manpage for details on Kerberos

authentication and authorization. However, it will not support integrity-checked or encrypted sessions.

The default Kerberos options for the applications are set in the

krb5.conf conﬁguration ﬁle. Refer to

the appdefaults Section in the krb5.conf (4) manpage for more information. The options -a, -f, and -F

described in the subsequent paragraphs, can be set in the krb5.conf ﬁle with the tag names

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (6 pages)

PAGE 1
telnet(1) telnet(1) NAME telnet - user interface to the TELNET protocol SYNOPSIS telnet [ [ options ] host [ port ] ] DESCRIPTION telnet is used to communicate with another host using the TELNET protocol. If telnet is invoked without arguments, it enters command mode, indicated by its prompt (telnet>). In this mode, it accepts and executes the commands listed below. If telnet is invoked with arguments, it performs an open command (see below) with those arguments.
PAGE 2
telnet(1) telnet(1) autologin, forward, and forwardable respectively. Refer to the appdefaults Section of the krb5.conf (4) manpage for more information. The fallback option can be set in the krb5.conf file within appdefaults Section . If fallback is set to true and the kerberos authentication fails, telnet will use the non-secure mode of authentication. Note: Command line options override configuration file options.
PAGE 3
telnet(1) telnet(1) EOF (normally ˆD; see stty (1)). Note: Setting line-mode also sets local echo. Applications that expect to interpret user input character by character (such as more, csh, ksh, and vi) do not work properly in line mode. status Show current status of telnet. telnet reports the current escape character. If telnet is connected, it reports the host to which it is connected and the current mode. If telnet is not connected to a remote host, it reports No connection.
PAGE 4
telnet(1) telnet(1) escape This is the telnet escape character (initially ˆ]) that causes entry into telnet command mode (when connected to a remote system). interrupt If telnet is in localchars mode (see toggle localchars below) and the interrupt character is typed, a TELNET IP sequence (see send ip above) is sent to the remote host. The initial value for the interrupt character is taken to be the terminal’s intr character.
PAGE 5
telnet(1) telnet(1) discarding all previously typed input until both of the TELNET sequences have been read and acted upon. The initial value of this toggle is FALSE. binary Enable or disable the TELNET BINARY option on both input and output. This option should be enabled in order to send and receive 8-bit characters to and from the TELNET server. crlf If TRUE, end-of-line sequences are sent as an ASCII carriage-return and linefeed pair.
PAGE 6
telnet(1) telnet(1) SEE ALSO csh(1), ksh(1), login(1), rlogin(1), stty(1), telnetd(1M), inetsvcs_sec(1M), hosts(4), krb5.conf(4), services(4), sis(5), termio(7).