A brute force attack attempts to guess a user's password by trying to log in multiple times. {project_name} has brute force detection capabilities and can temporarily disable a user account if the number of login failures exceeds a specified threshold.
{project_name} can deploy permanent lockout and temporary lockout actions when it detects an attack. Permanent lockout disables a user account until an administrator re-enables it. Temporary lockout disables a user account for a specific period of time.
The time period that the account is disabled increases as the attack continues and subsequent failures reach multiples of `Max Login Failures`.
When a user is temporarily locked and attempts to log in, {project_name} displays the default `Invalid username or password` error message. This message is the same error message as the message displayed for an invalid username or invalid password to ensure the attacker is unaware the account is disabled.
|The time when the failure count resets. The timer runs from the last failed login. Make sure this number is always greater than `Max wait`; otherwise the effective
wait time will never reach the value you have set to `Max wait`.
.. Calculate `wait` according the brute force strategy defined (see below Strategies to set Wait Time).
.. If `wait` equals is less than 0 and the time between this failure and the last failure is less than _Quick Login Check Milliseconds_, set `wait` to _Minimum Quick Login Wait_.
{project_name} provides two strategies to calculate wait time: By multiples or Linear. By multiples is the first strategy introduced by {project_name}, so that is the default one.
By multiples strategy, wait time is incremented when the number (or count) of failures are multiples of `Max Login Failure`. For instance, if you set `Max Login Failures` to `5` and a `Wait Increment` to `30` seconds, the effective time that an account is disabled after several failed authentication attempts will be:
At the fifth failed attempt of the `Effective Wait Time`, the account is disabled for `30` seconds. After reaching the next multiple of `Max Login Failures`, in this case `10`, the time increases from `30` to `60` seconds.
The By multiple strategy uses the following formula to calculate wait time: _Wait Increment_ * (`count` / _Max Login Failures_). The division is an integer division rounded down to a whole number.
For linear strategy, wait time is incremented when the number (or count) of failures equals or is greater than `Max Login Failure`. For instance, if you have set `Max Login Failures` to `5` and a `Wait Increment` to`30` seconds, the effective time that an account is disabled after several failed authentication attempts will be:
The downside of {project_name} brute force detection is that the server becomes vulnerable to denial of service attacks. When implementing a denial of service attack, an attacker can attempt to log in by guessing passwords for any accounts it knows and eventually causing {project_name} to disable the accounts.
Consider using intrusion prevention software (IPS). {project_name} logs every login failure and client IP address failure. You can point the IPS to the {project_name} server's log file, and the IPS can modify firewalls to block connections from these IP addresses.
Ensure you have a complex password policy to force users to choose complex passwords. See the <<_password-policies, Password Policies>> chapter for more information. Prevent password guessing by setting up the {project_name} server to use one-time-passwords.
