Linux是对用户的密码的复杂度要求设置【转】

retry=N
改变输入密码的次数，默认值是1。就是说，如果用户输入的密码强度不够就退出。可以使用这个选项设置输入的次数，以免一切都从头再来
 
              Prompt user at most N times before returning with error. The
              default is 1
 
minlen=N
新密码最低可接受的长度
 
              The minimum acceptable size for the new password (plus one if
              credits are not disabled which is the default). In addition to the
              number of characters in the new password, credit (of +1 in length)
              is given for each different kind of character (other, upper, lower
              and digit). The default for this parameter is 9 which is good for a
              old style UNIX password all of the same type of character but may
              be too low to exploit the added security of a md5 system. Note that
              there is a pair of length limits in Cracklib itself, a "way too
              short" limit of 4 which is hard coded in and a defined limit (6)
              that will be checked without reference to minlen. If you want to
              allow passwords as short as 5 characters you should not use this
              module.
 
difok=N
默认值为10。这个参数设置允许的新、旧密码相同字符的个数。不过，如果新密码中1/2的字符和旧密码不同，则新密码被接受
 
 
              This argument will change the default of 5 for the number of
              characters in the new password that must not be present in the old
              password. In addition, if 1/2 of the characters in the new password
              are different then the new password will be accepted anyway.
 
dcredit=N
限制新密码中至少有多少个数字
 
              (N >= 0) This is the maximum credit for having digits in the new
              password. If you have less than or N digits, each digit will count
              +1 towards meeting the current minlen value. The default for
              dcredit is 1 which is the recommended value for minlen less than
              10.
 
              (N < 0) This is the minimum number of digits that must be met for a
              new password.
 
ucredit=N
限制新密码中至少有多少个大写字符。
 
lcredit=N
限制新密码中至少有多少个小写字符。