Several types of passwords can be configured on a Cisco router, such as the enable password, the secret password for Telnet and SSH connections and the console port as well. All these password locations represent good access locations for passwords, but if you have only one password on only one access location, you should at least have an enable password.

1. How to configure the five main passwords of the Cisco IOS ? YASER RAHMATI
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AUX
This is short for auxiliary port. This is also a
physical access port on the router. Not all
routers have this port. As the aux port is a
backup configuration port for the console, it is
equally important to configure a password on
it.
Enable password
The enable password prevents someone from getting full access to your
router. The enable command is actually used to change between different
security levels on the router (there are 0-15 levels of security). However, it
is typically used to go from user mode (level 1) to privileged mode (level
15). In fact, if you are at user mode and you just type enable, it assumes
you want to go to privileged mode.
CONSOLE
If you have no password set on the router's
console, by default, you can access user mode .
Because there is only one console port per
router, you would use the command line
console 0 in global configuration mode.
VTY
The "virtual tty" line is not a physical
connection, but a virtual connection. You would
use this line to Telnet or SSH into the router.
Of course, you would need to have an active
LAN or WAN interface set up on your router for
Telnet to work.
Router# config t
Router(config)# line console 0
Router(config-line)# password SecR3t!pass
Router(config-line)# login
Router# config t
Router(config)# line aux 0
Router(config-line)# password SecR3t!pass
Router(config-line)# login
Router# config t
Router(config)# line vty 0 4
Router(config-line)# password SecR3t!pass
Router(config-line)# login
Enable secret
The enable secret password has the same function as the enable
password, but with enable secret, the password is stored in a much
stronger form of encryption:
Router# config t
Router(config)# enable password SecR3t!enable
Router(config)# exit
Router# config t
Router(config)# enable secret SecR3t!enable
Router(config)# exit