HP-UX Reference (11i v1 00/12) - 1M System Administration Commands N-Z (vol 4)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man1m/naaagt.1m
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t
telnetd(1M) Kerberos telnetd(1M)
NAME
telnetd - TELNET protocol server
SYNOPSIS
/usr/lbin/telnetd [-b [bannerfile]] [-A ][-a authmode][-t ]
DESCRIPTION
The telnetd daemon executes a server that supports the DARPA standard TELNET virtual terminal
protocol. The Internet daemon (inetd) executes telnetd when it receives a service request at the port
listed in the services data base for telnet using the tcp protocol (see inetd(1M) and services(4)).
telnetd operates by allocating a Telnet pseudo-terminal device (see tels(7)) for a client, then creating a
login process which has the slave side of the Telnet pseudo-terminal as stdin, stdout, and stderr.
telnetd manipulates the master side of the Telnet pseudo-terminal, implementing the TELNET protocol,
and passing characters between the client and login process.
NOTE: telnetd no longer uses pty(7) devices; instead it uses special devices created for TELNET ses-
sions only. For a full description, see tels(7).
When a TELNET session is started up, telnetd sends TELNET options to the client side, indicating a
willingness to do remote echo of characters, to suppress go ahead, and to receive terminal speed, terminal
type, and authentication information from the remote client. If the remote client is willing, the remote ter-
minal type is propagated in the environment of the created login process. The Telnet pseudo-terminal allo-
cated to the client is configured as a normal terminal with the exception of echoing characters (see tty(7)).
telnetd is willing to do: echo, binary, suppress go ahead, and timing mark.
telnetd is willing to have the remote client do: binary, flow control, terminal speed, terminal type,
suppress go ahead, and authentication.
The flow control option permits applications running on a remote host to toggle the flow control on the local
host. To toggle flow control for a
telnet session programmatically, the application program must first
call the tcgetattr function to get the current termios settings. For example,
tcgetattr(filedes,
&termios_p)
Then, the c_iflag of the termios structure must have IXON set(reset) to enable(disable) flow control.
Finally, the tcsetattr function call can implement the change. For example,
tcsetattr(filedes,
TCSANOW, &termios_p)
To toggle the flow control interactively, the user can issue a
stty command using the input options -
ixon
to disable, or ixon to enable flow control. (see stty(1)).
The terminal speed option permits applications running on a remote host to obtain the terminal speed of
the local host session using either ioctl or stty.
By default, the telnet server provides remote execution facilities with authentication based on Kerberos
V5. (See sis(5).)
The telnet server also supports the TAC User ID (also known as the TAC Access Control System, or
TACACS User ID) option, whereby users telneting to two or more consenting hosts may avoid going
through a second login sequence. See the -t option below.
To start telnetd from the Internet daemon, the configuration file /etc/inetd.conf
must contain an
entry as follows:
telnet stream tcp nowait root /usr/lbin/telnetd telnetd
With this Kerberos version of telnetd, inetd can start telnetd with the following lines in
/etc/inetd.conf. See the -A and -a options below.
telnet stream tcp nowait root /usr/lbin/telnetd telnetd -A
or
telnet stream tcp nowait root /usr/lbin/telnetd telnetd -a valid
telnet
uses the same files as rlogin to verify participating systems and authorized users,
hosts.equiv and .rhosts. (See hosts.equiv(4) and the Managing Systems and Workgroups manual
for configuration details.)
Section 1M−−962 − 1 − HP-UX Release 11i: December 2000
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