dacspasswd - Online in the Cloud

PROGRAM:

NAME

dacspasswd - manage DACS accounts

SYNOPSIS

dacspasswd [dacsoptions[1]] [-p password] [-pf file] [-simple] [-vfs vfs_uri]
[op-spec] [--] [username]

DESCRIPTION

This program is part of the DACS suite.

The dacspasswd command manages accounts that are used by the local_passwd_authenticate[2]
and local_simple_authenticate[3], authentication modules. This utility serves a similar
purpose for these authentication modules that Apache's htpasswd(1)[4] command does for its
mod_auth[5] and mod_auth_dbm[6] modules (or mod_auth_basic[7] and mod_authn_dbm[8]).

Apart from their use by local_passwd_authenticate and local_simple_authenticate, these
accounts are completely separate from any other accounts and passwords.

Note
Only lowercase usernames are permitted for these accounts.

The command allows arbitrary data to be associated with each account. This "private" data
is opaque to DACS and is not used by DACS. Custom, account-specific information can be
stored, retrieved, and deleted. Data that is not printable text must be encoded. The
information is automatically deleted when its account is removed. Using this feature,
account administration programs might be developed to store:

· the last time a password was changed;

· hashes of previous password values (so that they are not reused);

· a note that the account's password must be changed;

· a password reminder question and answer;

· information for mutual authentication, such as a small image provided by the user that
is displayed at login time;

· an encrypted representation of the password for recovery purposes (when absolutely
necessary)

· several security questions (with answers), one of which might be selected at random
and presented to the user at login time; or

· user preferences.

Or instead, a pointer to any of this sort of information might be stored. There is no size
limit for the data, but if relatively large amounts of data are being stored for a large
number of accounts, the storage type should be chosen with care to ensure reasonable
performance.

Passwords are accessed using the DACS virtual filestore through the passwds or simple item
types. Each record in the file is keyed on the username. The information associated with
each key consists of several fields separated by a "|" character, and includes a digest
algorithm identifier, salt, the computed digest, and optional application data.

Security
The password digest algorithm used depends on the PASSWORD_DIGEST[9] directive in
effect. The PASSWORD_SALT_PREFIX[10] directive is also used.

Plaintext passwords are not stored by dacspasswd. This makes it more difficult for an
attacker that gains access to the password file to discover plaintext passwords, but
also means that forgotten passwords cannot be recovered (except by exhaustive search,
which ought to be impractical).

The salted hash of the password is stored, assuming salting has not been disabled,
rather than the hash of the password itself. This makes a stolen password file more
difficult for an attacker to use (see rainbow tables[11]).

Only a DACS administrator should be able to successfully run this program from the
command line. Because DACS keys and configuration files, including the file used to
store passwords, must be restricted to an administrator, this will normally be the
case, but a careful administrator will set file permissions to deny access to all
other users. An ordinary user is able to change his own password using the
dacs_passwd(8)[12] web service.

Tip
Even if the password file is stored as a plain text file, it is probably best to
modify it only through this program or dacs_passwd.

It is good administrative practice to store accounts with passwords separately from
those without.

This program is also available as a DACS web service, dacs_passwd(8)[12].

OPTIONS

By default, the program will prompt for a new password if one is required by the selected
operation.

The dacspasswd command recognizes these command line flags:

-p password
Specify the password.

Security
A password given on the command line may be visible to other users on the same
system.

-pdd
Delete the private data associated with username.

-pdg
Get the private data associated with username and print it to the standard output.

-pds string
Set (or replace) string as private data associated with username.

-pdsf file
Set (or replace) the private data associated with username, reading it from file. If
file is "-", then the data is read from the standard input. This flag and -pf cannot
both be used to read from the standard input.

-pf file
Read the password to use from file. If file is "-", then the password is read from the
standard input without prompting. This flag and -pdsf cannot both be used to read from
the standard input.

-simple
Use the simple item type expected by local_simple_authenticate instead of the default.
The program will not prompt for passwords because these accounts do not use them.

-vfs vfs_uri
Add vfs_uri as a VFS[13] configuration directive. By specifying the item type passwds,
a location for the password file can be given, overriding any configuration file
value. This is particularly useful in conjunction with dacsauth(1)[14].

op-spec
The following operations are recognized. The -enable, -disable, -pdd, -pds, and -pdsf
are the only operations that can be combined with another operation (for example, you
can disable an account and set its private data at the same time).

-a
-add
Add username to the password file. The entry must not already exist. By default,
the user will be prompted for the password, which must be retyped for
confirmation. This is the default operation.

-d
-del
-delete
Delete username from the password file.

-dis
-disable
Disable the account for username so that authentication modules will not accept
any password. If used with -a, -s, or -u, the account will also be disabled. The
username may subsequently be enabled.

-en
-ena
-enable
Re-enable the account for username, which is currently disabled. The
authentication modules will once again accept the password. If used with -a, -s,
or -u, the account will also be enabled.

-g
-get
Get the digest string for username and print it to the standard output. A script
can validate a password by passing this digest string to password()[15] along with
the password obtained from the user.

-l
-list
List username if it appears in the password file. If no username is provided, list
all usernames. A disabled account is indicated by a '*' (which is not a valid
character in a username).

-s
-set
Set or reset the password for username, which must already exist in the password
file. The enabled/disabled status is preserved unless overridden by a flag.

-test testop
Test an entry for one of several attributes and report the outcome through the
program's exit status. The testop is one of the following keywords or abbreviated
keywords:

· enabled, ena, en

Return an exit status of 0 if an account for username exists and is enabled,
or 1 if it does not exist or is disabled.

· exists, ex

Return an exit status of 0 if an account for username exists, or 1 if it does
not exist.

· data

Return an exit status of 0 if an account for username exists and has private
data, or 1 if it does not exist or does not have private data. If an entry's
private data is the empty string, it is considered to have private data.

· disabled, dis

Return an exit status of 0 if an account for username exists and is disabled,
or 1 if it does not exist or is enabled.

-u
-up
-update
Add username to the password file or update an existing entry for username. By
default, the user will be prompted for the password, which must be retyped for
confirmation. If the entry exists, the enabled/disabled status is preserved unless
overridden by a flag.

--
This flag signals the end of the flag arguments; a username may follow, possibly
beginning with a "-" character.

Since only the administrator is allowed to use this command, no restrictions are imposed
on the length or quality of the passwords that the administrator supplies; a warning
message will be emitted, however, if the password is considered to be weak based on the
PASSWORD_CONSTRAINTS[16] directive that is configured.

EXAMPLES

To list all of the accounts configured for the jurisdiction named EXAMPLE:

% dacspasswd -uj EXAMPLE -list
auggie
bobo*
booboo
jj

Note that the account for username bobo has been disabled.

To re-enable bobo's account:

% dacspasswd -uj EXAMPLE -ena bobo

To test if bobo's account is enabled:

% dacspasswd -uj EXAMPLE -test ena bobo
% echo $status
0

To test if there are accounts for usernames booboo and bob:

% dacspasswd -uj EXAMPLE -test exists booboo
% echo $status
0
% dacspasswd -uj EXAMPLE -test exists bob
% echo $status
1

To reset the password for username bobo interactively:

% dacspasswd -uj EXAMPLE -set bobo
New password for bobo?
Re-type new password for bobo?

Note that the password text is not displayed.

To reset the password for username bobo using the program's standard input:

% echo $newpasswd | dacspasswd -uj EXAMPLE -set -pf - bobo

To create a new, disabled account for username bob and store the private data "On
vacation":

% dacspasswd -uj EXAMPLE -add -pf ./pwfile -dis -pds "On vacation" bob

The password is read from the file ./pwfile.

To get the private data for username bob:

% set x=`dacspasswd -uj EXAMPLE -pdg bob`
% echo "$x"
On vacation

DIAGNOSTICS

The program exits 0 if everything was fine, and non-zero otherwise. A "false" outcome from
the -test operation is reflected by an exit status of 1. An error condition is indicated
by an exit status of 2.

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