(Optional) Enabling the IP Address Blocking Function for Telnet Connections
The IP address blocking function for Telnet connections prevents IP addresses that fail to be authenticated from logging in to a device through Telnet. If this function is disabled, the device is vulnerable to network attacks.
Context
When a device functions as a Telnet server, you can configure the IP address blocking function to protect the device against network attacks, thereby enhancing security.
Perform the following steps on a device that functions as a Telnet server.
Procedure
- Run system-view
The system view is displayed.
- Run undo telnet server ip-block disable
The IP address blocking function is enabled for Telnet connections.
- Run commit
The configuration is committed.
The IP addresses that fail to be authenticated are blocked only when the IP address blocking function is enabled. This enhances device security.
- The IP addresses that fail to be authenticated will be locked for 5 minutes. To unlock a locked IP address in advance, perform the following steps:
- Run the quit command to exit the system view and enter the user view.
- Run the activate vty ip-block ip-address ip-address [ vpnname vpn-name ] command to unblock the IP address that fails to be authenticated for Telnet connections.