Linux in a Nutshell, Fourth Edition

Name

telnetd

Synopsis

                  telnetd [options]

TCP/IP command. Telnet protocol server. telnetd is invoked by the Internet server for requests to connect to the Telnet port (port 23 by default). telnetd allocates a pseudo-terminal device for a client, thereby creating a login process that has the slave side of the pseudo-terminal serving as stdin, stdout, and stderr. telnetd manipulates the master side of the pseudo-terminal by implementing the Telnet protocol and by passing characters between the remote client and the login process.

The Telnet protocol is often criticized because it uses no encryption and makes it easy for snoopers to pick up user passwords. Most sites now use ssh instead.

Options

-a type

When compiled with authentication support, this option sets the authentication type. Accepted values are:

debug

Debug authentication code.

user

Allow only authenticated remote users with permission to access their accounts without giving a password.

valid

Allow only authenticated remote users. Use login for any additional verification needed to access an account.

none

No authentication required, but accept it if offered. Use login for any further verification needed to access an account.

off

Disable authentication.

-debug [port]

Start telnetd manually instead of through inetd. port may be specified as an alternate TCP port number on which to run telnetd.

-D modifier(s)

Debugging mode. This allows telnet to print out debugging information to the connection, enabling the user to see what telnet ...