TELNETD(8)
NAME
telnetd − DARPA TELNET protocol server
USAGE
/etc/telnetd [ −d ] [ port ]
DESCRIPTION
Telnetd is a server for the DARPA standard TELNET virtual terminal protocol. The TELNET server operates at the port indicated in the “telnet” service description; see services(5). This port number may be overridden (for debugging purposes) by specifying a port number on the command line.
OPTIONS
−d enables debugging on each socket created by telnetd (see SO_DEBUG in socket(2)).
Telnetd operates by allocating a pseudo-terminal device for a client, then creating a log-in process that has the slave side of the pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the master side of the pseudo terminal, implementing the TELNET protocol and passing characters between the client and log-in process.
When a TELNET session is started up, telnetd sends a TELNET option to the client side indicating a willingness to perform “remote echo” of characters. The pseudo terminal allocated to the client is configured to operate in “cooked” mode, and with XTABS and CRMOD enabled. Aside from this initial setup, the only mode changes telnetd will carry out are those required for echoing characters at the client side of the connection.
Telnetd supports binary mode, and most of the common TELNET options. It does not, however, support all of them. Consult the source code for an exact list of which options are implemented.
NOTES
A complete list of the options supported is not available at this time.