HP-UX Directory Server 8.1 deployment guide

8.6.2.10 Password storage schemes
The password storage scheme specifies the type of encryption used to store Directory Server
passwords within the directory. The Directory Server supports several different password storage
schemes:
• Salted Secure Hash Algorithm (SSHA, SSHA-256, SSHA-384, and SSHA-512).
This is the most secure password storage scheme and is the default. The recommended
SSHA scheme is SSHA-256 or stronger.
• CLEAR
No encryption. This is the only option which can be used with SASL Digest-MD5, so using
SASL requires the CLEAR password storage scheme.
Although passwords stored in the directory can be protected through the use of access
control information (ACI) instructions, it is still not a good idea to store plain text passwords
in the directory.
• Secure Hash Algorithm (SHA, SHA-256, SHA-384, and SHA-512)
This is less secure than SSHA.
• UNIX CRYPT algorithm
This algorithm provides compatibility with UNIX passwords.
• MD5
This storage scheme is less secure than SSHA, but it is included for legacy applications which
require MD5.
8.6.3 Designing an account lockout policy
After establishing a password policy for the directory service, protect user passwords from
potential threats by configuring an account lockout policy.
The lockout policy works in conjunction with the password policy to provide further security.
The account lockout feature protects against crackers who try to break into the directory by
repeatedly trying to guess a user's password. A specific user can be locked out of the directory
after a given number of failed attempts to bind.
8.6.4 Designing a password policy in a replicated environment
Password and account lockout policies are enforced in a replicated environment as follows:
• Password policies are enforced on the data master.
• Account lockout is enforced on all servers in the replication setup.
The password policy information in the directory, such as password age, the account lockout
counter, and the expiration warning counter, are all replicated. The configuration information,
however, is stored locally and is not replicated. This information includes the password syntax
and the history of password modifications.
When configuring a password policy in a replicated environment, consider the following points:
• All replicas issue warnings of an impending password expiration. This information is kept
locally on each server, so if a user binds to several replicas in turn, the user receives the same
warning several times. In addition, if the user changes the password, it may take time for
this information to filter through to the replicas. If a user changes a password, then
immediately rebinds, the bind may fail until the replica registers the changes.
• The same bind behavior should occur on all servers, including suppliers and replicas. Always
create the same password policy configuration information on each server.
• Account lockout counters may not work as expected in a multi-master environment.
116 Designing a secure directory