for my $user (keys %users) {
    print "dn: uid=$user\n",
        "givenName: $users{$user}{first_name}\n",
        "sn: $user{$user}{last_name}\n",
        #etc...
        "telephonNumber: $users{$user}{phone_number}\n",
        "faxNumber: $users{$user}{fax_number}\n";
}