3-3
To improve security and prevent attacks to the unused Sockets, TCP 23 and TCP 22, ports for Telnet
and SSH services respectively, will be enabled or disabled after corresponding configurations.
z If the authentication mode is none, TCP 23 will be enabled, and TCP 22 will be disabled.
z If the authentication mode is password, and the corresponding password has been set, TCP 23
will be enabled, and TCP 22 will be disabled.
z If the authentication mode is scheme, there are three scenarios: when the supported protocol is
specified as telnet, TCP 23 will be enabled; when the supported protocol is specified as ssh, TCP
22 will be enabled; when the supported protocol is specified as all, both the TCP 23 and TCP 22
port will be enabled.
Telnet Configuration with Authentication Mode Being None
Configuration Procedure
Follow these steps to perform Telnet configuration with the authentication mode being none:
To do… Use the command… Remarks
Enter system view system-view —
Enter one or more VTY user
interface views
user-interface vty
first-number
[ last-number ] —
Configure not to authenticate
users logging in to VTY user
interfaces
authentication-mode
none
Required
By default, VTY users are authenticated
after logging in.
Configure the command level
available to users logging in to
VTY user interface
user privilege level
level
Optional
By default, commands of level 0 are
available to users logging in to VTY
user interfaces.
Configure the protocols to be
supported by the VTY user
interface
protocol inbound { all |
ssh | telnet }
Optional
By default, both Telnet protocol and
SSH protocol are supported.
Set the commands to be
executed automatically after a
user login to the user interface
successfully
auto-execute
command text
Optional
By default, no command is executed
automatically after a user logs in to the
VTY user interface.
Make terminal services
available shell Optional
By default, terminal services are
available in all user interfaces.
Set the maximum number of
lines the screen can contain screen-length
screen-length
Optional
By default, the screen can contain up to
24 lines.
You can use the screen-length 0
command to disable the function to
display information in pages.