3.6 Implementing Intruder Detection and Lockout Mechanisms

Sentinel supports intruder detection and lockout to prevent potential brute-force attacks. Sentinel provides several configurable parameters that help you implement intruder detection and lockout mechanisms.

  • failedAuthDelay: Specifies the duration in milliseconds that a subsequent authentication request must wait after a failed authentication for a specific user. The default value is 2000 (2 seconds). If the value is 0, the delay is disabled. This wait period is calculated for each user. If an authentication request for User A fails, it does not cause a delay for an authentication request for User B.

  • intruderDetectInterval: Specifies the time period in milliseconds in which consecutive failed authentication requests for a user must occur for Sentinel to identify the failures as a possible intruder detection. For example, if the value is 300000 (5 minutes) and four failed authentication requests happen within 4 minutes, but the 5th consecutive request happens 5:01 (minutes:seconds) later than the 1st failed request, Sentinel does not consider the requests suspicious. If the value is 360000 (6 minutes) and the same sequence of failed requests happen, Sentinel considers the requests to be suspicious. The default value for this parameter is 300000 (5 minutes).

  • intruderDetectMaxFailedAttempts: Specifies the number of consecutive, failed authentication requests that must occur for Sentinel to consider a user name during the intruderDetectInterval for the requests as suspicious. If the value is 0 then intruder detection and lockout is disabled. The default value for this parameter is 5.

  • intruderDetectLockPeriod: Specifies the duration that a Sentinel user account remains locked when the user account is automatically locked in response to a suspicious series of failed authentication requests. If the value is 0, automatically locked accounts are not automatically unlocked. They must be unlocked manually by an administrator. The default value for this parameter is 900000 (15 minutes).

  • intruderDetectAdminAutoLock: Specifies whether or not the Sentinel admin account is subject to automatic locking in response to a series of failed authentication requests. The default is false since a denial-of-service attack exists in which an attacker can continually lock the built-in admin account, unless there is a separate administrator account.

The values listed above are defined in the AuthenticationService component of the /etc/opt/novell/sentinel/config/server.xml file. To customize the AuthenticationService component, see Maintaining Custom Settings in XML Files.