.\" Copyright (c) 1983 Regents of the University of California. .\" All rights reserved. The Berkeley software License Agreement .\" specifies the terms and conditions for redistribution. .\" .\" @(#)telnetd.8c 6.3 (Berkeley) 5/28/86 .\" .TH TELNETD 8C "May 28, 1986" .UC 5 .SH NAME telnetd \- DARPA TELNET protocol server .SH SYNOPSIS .B /etc/telnetd .SH DESCRIPTION .I Telnetd is a server which supports the DARPA standard .B TELNET virtual terminal protocol. .I Telnetd is invoked by the internet server (see .IR inetd (8)), normally for requests to connect to the .B TELNET port as indicated by the .I /etc/services file (see .IR services (5)). .PP .I Telnetd operates by allocating a pseudo-terminal device (see .IR pty (4)) for a client, then creating a login process which has the slave side of the pseudo-terminal as .BR stdin , .BR stdout , and .BR stderr . .I Telnetd manipulates the master side of the pseudo-terminal, implementing the .B TELNET protocol and passing characters between the remote client and the login process. .PP When a .B TELNET session is started up, .I telnetd sends .B TELNET options to the client side indicating a willingness to do .I remote echo of characters, to .I suppress go .IR ahead , and to receive .I terminal type information from the remote client. If the remote client is willing, the remote terminal type is propagated in the environment of the created login process. The pseudo-terminal allocated to the client is configured to operate in \*(lqcooked\*(rq mode, and with XTABS and CRMOD enabled (see .IR tty (4)). .PP .I Telnetd is willing to .IR do : .IR echo , .IR binary , .I suppress go .IR ahead , and .I timing .IR mark . .I Telnetd is willing to have the remote client .IR do : .IR binary , .I terminal .IR type , and .I suppress go .IR ahead . .SH "SEE ALSO" telnet(1C) .SH BUGS Some .B TELNET commands are only partially implemented. .PP The .B TELNET protocol allows for the exchange of the number of lines and columns on the user's terminal, but .I telnetd doesn't make use of them. .PP Because of bugs in the original 4.2 BSD .IR telnet (1C), .I telnetd performs some dubious protocol exchanges to try to discover if the remote client is, in fact, a 4.2 BSD .IR telnet (1C). .PP .I Binary mode has no common interpretation except between similar operating systems (Unix in this case). .PP The terminal type name received from the remote client is converted to lower case. .PP The .I packet interface to the pseudo-terminal (see .IR pty (4)) should be used for more intelligent flushing of input and output queues. .PP .I Telnetd never sends .B TELNET .I go ahead commands.