Cisco ASA: Configuring Telnet April 8
In order to add Telnet access to the console and set the idle timeout, issue the telnet command in global configuration mode. By default, Telnet sessions that are left idle for five minutes are closed by the security appliance. In order to remove Telnet access from a previously set IP address, use the no form of this command.
telnet {{hostname | IP_address mask interface_name} | {IPv6_address interface_name} | {timeout number}}
no telnet {{hostname | IP_address mask interface_name} | {IPv6_address interface_name} | {timeout number}}
The telnet command lets you specify which hosts can access the security appliance console with Telnet. You can enable Telnet to the security appliance on all interfaces. But, the security appliance enforces that all Telnet traffic to the outside interface be protected by IPsec. In order to enable a Telnet session to the outside interface, configure IPsec on the outside interface to include IP traffic that is generated by the security appliance and enable Telnet on the outside interface.
Note: It is not recommended to access the security appliance through a Telnet session. The authentication credential information, such as password, is sent as clear text. The Telnet server and client communication happens only with the clear text. Cisco recommends to use SSH for a more secured data communication.
