telnet - 0.17-41.2 main

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