Unknown Command or Computer Name
The Problem
Typing the wrong commands in Cisco CLI … the equipment tries to use telnet.
R1# aoeu
Translating "aoeu"...domain server (255.255.255.255)
(255.255.255.255)
Translating "aoeu"...domain server (255.255.255.255)
% Bad IP address or host name
% Unknown command or computer name, or unable to find computer address
This is from the IOS-XE guide.
The Cisco IOS software accepts a host name entry at the EXEC prompt as a Telnet command.
If you enter the host name incorrectly, the Cisco IOS software interprets the entry as an incorrect Telnet command and provides an error message indicating that the host does not exist.
The transport preferred none command disables this option so that if you enter a command incorrectly at the EXEC prompt, the Cisco IOS software does not attempt to make a Telnet connection.
Config
configure terminal
line console 0
transport preferred none
line vty 0 15
transport preferred none
end
copy run start
Verify
R1# aoeu
^
% Invalid input detected at '^' marker.
R1#
Longer Verification
DNS still works.
DNS resolution in show commands is enabled
The box will not attempt telnet on typing stuff into the CLI now.
Preferred transport is none
R1# show terminal
Line 0, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Status: PSI Enabled, Ready, Active, Automore On
Capabilities: none
Modem state: Ready
Group codes: 0
Modem hardware state: CTS* noDSR DTR RTS
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:10:00 never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Modem type is unknown.
Session limit is not set.
Time since activation: 00:05:35
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are none.
Allowed output transports are lat pad telnet rlogin lapb-ta mop v120 ssh.
Preferred transport is none.
Shell: disabled
Shell trace: off
No output characters are padded
No special data dispatching characters