Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル

If you forget your password while logged out of the CLI, you can use 

the bootloader to reinstall a default switch configuration, which 
allows access to the switch without a password.  Note that this 
process reconfigures all switch settings back to the initial default 
configuration.

Applying Security to Passwords

You can increase the security of your system by enforcing password restrictions, which will 
make it more difficult for unauthorized users to access your system.

You can specify that each password must include at least two characters of each of the 
following four character types:

Upper-case A-Z

Lower-case a-z

0-9

!, @, #, $, %, ^, *, (, )

To set this format for the password, use the following command:

configure account [all | <name>] password-policy char-validation [none | all-char-groups]

You can enforce a minimum length for the password and set a maximum time limit, after 
which the password will not be accepted. 

To set a minimum length for the password, use the following command:

configure account [all | <name>] password-policy min-length [<num_characters> | none]

To age out the password after a specified time, use the following command:

configure account [all | <name>] password-policy max-age [<num_days> | none]

You can block users from employing previously used passwords by issuing the command:

configure account [all | <name>] password-policy history [<num_passwords> | none]

By default, the system terminates a session after the user has three consecutive failed login 
attempts. The user may then launch another session (which again would terminate after 
three consecutive failed login attempts). To increase security, you can lock users out of the 
system entirely after three failed consecutive login attempts. To use this feature, use the 
following command:

configure account [all | <name>] password-policy lockout-on-login-failures [on | off]