telnet

The telnet command is used for interactive communication with another host using the TELNET protocol.

For the purpose of remote login, the present client executable should be depreciated in favour of an ssh-client, or in some cases with variants like telnet-ssl or Kerberized TELNET clients. The most important reason is that this implementation exchanges user name and password in clear text.

On the other hand, the present program does satisfy common use cases of network diagnostics, like protocol testing of SMTP services, so it can become handy enough.

Installed size: 166 KB
How to install: sudo apt install telnet

telnet.netkit

User interface to the TELNET protocol

[email protected]:~# telnet.netkit -h
telnet.netkit: invalid option -- 'h'
Usage: telnet.netkit [-4] [-6] [-8] [-E] [-L] [-a] [-d] [-e char] [-l user]
	[-n tracefile] [ -b addr ] [-r] [host-name [port]]

telnetd

The in.telnetd program is a server which supports the DARPA telnet interactive communication protocol.

This legacy server should in general be abandoned in favour of a contemporary ssh-server, as this implementation only is able to process password and user name in clear text. Other variants, like telnetd-ssl and a selection of Kerberized TELNET servers, are able to improve on this by providing secure forms of authentication and encryption.

Installed size: 115 KB
How to install: sudo apt install telnetd

in.telnetd

DARPA telnet protocol server

[email protected]:~# in.telnetd --help
in.telnetd: invalid option -- '-'
Usage: telnetd [-debug port] [-D (options|report|exercise|netdata|ptydata)]
	 [-h] [-L login_program] [-n]

in.telnetd

DARPA telnet protocol server

[email protected]:~# in.telnetd --help
in.telnetd: invalid option -- '-'
Usage: telnetd [-debug port] [-D (options|report|exercise|netdata|ptydata)]
	 [-h] [-L login_program] [-n]