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userdbpw(8)


NAME

   userdbpw - create an encrypted password

SYNOPSIS

   userdbpw [[-md5] | [-hmac-md5] | [-hmac-sha1]] |userdb {name} set
                  {field}

DESCRIPTION

   userdbpw enables secure entry of encrypted passwords into
   /etc/courier/userdb.

   userdbpw reads a single line of text on standard input, encrypts it,
   and prints the encrypted result to standard output.

   If standard input is attached to a terminal device, userdbpw explicitly
   issues a "Password: " prompt on standard error, and turns off echo
   while the password is entered.

   The -md5 option is available on systems that use MD5-hashed passwords
   (such as systems that use the current version of the PAM library for
   authenticating, with MD5 passwords enabled). This option creates an MD5
   password hash, instead of using the traditional crypt() function.

   -hmac-md5 and -hmac-sha1 options are available only if the userdb
   library is installed by an application that uses a challenge/response
   authentication mechanism.  -hmac-md5 creates an intermediate HMAC
   context using the MD5 hash function.  -hmac-sha1 uses the SHA1 hash
   function instead. Whether either HMAC function is actually available
   depends on the actual application that installs the userdb library.

   Note that even though the result of HMAC hashing looks like an
   encrypted password, it's really not. HMAC-based challenge/response
   authentication mechanisms require the cleartext password to be
   available as cleartext. Computing an intermediate HMAC context does
   scramble the cleartext password, however if its compromised, it WILL be
   possible for an attacker to succesfully authenticate. Therefore,
   applications that use challenge/response authentication will store
   intermediate HMAC contexts in the "pw" fields in the userdb database,
   which will be compiled into the userdbshadow.dat database, which has
   group and world permissions turned off. The userdb library also
   requires that the cleartext userdb source for the userdb.dat and
   userdbshadow.dat databases is also stored with the group and world
   permissions turned off.

   userdbpw is usually used together in a pipe with userdb, which reads
   from standard input. For example:

       userdbpw -md5 | userdb users/john set systempw

   or:

       userdbpw -hmac-md5 | userdb users/john set hmac-md5pw

   These commands set the systempw field in the record for the user john
   in /etc/courier/userdb/users file, and the hmac-md5pw field. Don't
   forget to run makeuserdb for the change to take effect.

   The following command does the same thing:

       userdb users/john set systempw=SECRETPASSWORD

   However, this command passes the secret password as an argument to the
   userdb command, which can be viewed by anyone who happens to run ps(1)
   at the same time. Using userdbpw allows the secret password to be
   specified in a way that cannot be easily viewed by ps(1).

SEE ALSO

   userdb(8)[1], makeuserdb(8)[2]

NOTES

    1. userdb(8)
       [set $man.base.url.for.relative.links]/userdb.html

    2. makeuserdb(8)
       [set $man.base.url.for.relative.links]/makeuserdb.html



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