3Com 3C13618 Command Reference Manual page 655

Telnet terminal user (telnet): Telnet connection shut down if authentication fails
three times.
For related commands, see local-user callback-number, local-user password,
local-user call-number, local-user ftp-directory, local-user service-type.
Example
# Turn on the Telnet terminal user authentication switch.
[3Com]login telnet
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