Provided by: apache2-utils_2.4.63-1ubuntu3_amd64 
NAME
htdbm - Manipulate DBM password databases
SYNOPSIS
htdbm [ -TDBTYPE ] [ -i ] [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] filename username
htdbm -b [ -TDBTYPE ] [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] filename username
password
htdbm -n [ -i ] [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] username
htdbm -nb [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] username password
htdbm -v [ -TDBTYPE ] [ -i ] [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] filename
username
htdbm -vb [ -TDBTYPE ] [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -t ] [ -v ] filename username
password
htdbm -x [ -TDBTYPE ] filename username
htdbm -l [ -TDBTYPE ]
SUMMARY
htdbm is used to manipulate the DBM format files used to store usernames and password for basic
authentication of HTTP users via mod_authn_dbm. See the dbmmanage documentation for more information
about these DBM files.
OPTIONS
-b Use batch mode; i.e., get the password from the command line rather than prompting for it. This
option should be used with extreme care, since the password is clearly visible on the command
line. For script use see the -i option.
-i Read the password from stdin without verification (for script usage).
-c Create the passwdfile. If passwdfile already exists, it is rewritten and truncated. This option
cannot be combined with the -n option.
-n Display the results on standard output rather than updating a database. This option changes the
syntax of the command line, since the passwdfile argument (usually the first one) is omitted. It
cannot be combined with the -c option.
-m Use MD5 hashing for passwords. On Windows and Netware, this is the default.
-B Use bcrypt hashing for passwords. This is currently considered to be very secure.
-C This flag is only allowed in combination with -B (bcrypt hashing). It sets the computing time used
for the bcrypt algorithm (higher is more secure but slower, default: 5, valid: 4 to 31).
-d Use crypt() hashing for passwords. The default on all platforms but Windows and Netware. Though
possibly supported by htdbm on all platforms, it is not supported by the httpd server on Windows
and Netware. This algorithm is insecure by today's standards.
-s Use SHA hashing for passwords. Facilitates migration from/to Netscape servers using the LDAP
Directory Interchange Format (ldif). This algorithm is insecure by today's standards.
-p Use plaintext passwords. Though htdbm will support creation on all platforms, the httpd daemon
will only accept plain text passwords on Windows and Netware.
-l Print each of the usernames and comments from the database on stdout.
-v Verify the username and password. The program will print a message indicating whether the supplied
password is valid. If the password is invalid, the program exits with error code 3.
-x Delete user. If the username exists in the specified DBM file, it will be deleted.
-t Interpret the final parameter as a comment. When this option is specified, an additional string
can be appended to the command line; this string will be stored in the "Comment" field of the
database, associated with the specified username.
filename
The filename of the DBM format file. Usually without the extension .db, .pag, or .dir. If -c is
given, the DBM file is created if it does not already exist, or updated if it does exist.
username
The username to create or update in passwdfile. If username does not exist in this file, an entry
is added. If it does exist, the password is changed.
password
The plaintext password to be hashed and stored in the DBM file. Used only with the -b flag.
-TDBTYPE
Type of DBM file (SDBM, GDBM, DB, or "default").
BUGS
One should be aware that there are a number of different DBM file formats in existence, and with all
likelihood, libraries for more than one format may exist on your system. The three primary examples are
SDBM, NDBM, GNU GDBM, and Berkeley/Sleepycat DB 2/3/4. Unfortunately, all these libraries use different
file formats, and you must make sure that the file format used by filename is the same format that htdbm
expects to see. htdbm currently has no way of determining what type of DBM file it is looking at. If used
against the wrong format, will simply return nothing, or may create a different DBM file with a different
name, or at worst, it may corrupt the DBM file if you were attempting to write to it.
One can usually use the file program supplied with most Unix systems to see what format a DBM file is in.
EXIT STATUS
htdbm returns a zero status ("true") if the username and password have been successfully added or updated
in the DBM File. htdbm returns 1 if it encounters some problem accessing files, 2 if there was a syntax
problem with the command line, 3 if the password was entered interactively and the verification entry
didn't match, 4 if its operation was interrupted, 5 if a value is too long (username, filename, password,
or final computed record), 6 if the username contains illegal characters (see the Restrictions section),
and 7 if the file is not a valid DBM password file.
EXAMPLES
htdbm /usr/local/etc/apache/.htdbm-users jsmith
Adds or modifies the password for user jsmith. The user is prompted for the password. If executed on a
Windows system, the password will be hashed using the modified Apache MD5 algorithm; otherwise, the
system's crypt() routine will be used. If the file does not exist, htdbm will do nothing except return an
error.
htdbm -c /home/doe/public_html/.htdbm jane
Creates a new file and stores a record in it for user jane. The user is prompted for the password. If the
file exists and cannot be read, or cannot be written, it is not altered and htdbm will display a message
and return an error status.
htdbm -mb /usr/web/.htdbm-all jones Pwd4Steve
Encrypts the password from the command line (Pwd4Steve) using the MD5 algorithm, and stores it in the
specified file.
SECURITY CONSIDERATIONS
Web password files such as those managed by htdbm should not be within the Web server's URI space -- that
is, they should not be fetchable with a browser.
The use of the -b option is discouraged, since when it is used the plaintext password appears on the
command line.
When using the crypt() algorithm, note that only the first 8 characters of the password are used to form
the password. If the supplied password is longer, the extra characters will be silently discarded.
The SHA hashing option does not use salting: for a given password, there is only one hashed
representation. The crypt() and MD5 formats permute the representation by prepending a random salt
string, to make dictionary attacks against the passwords more difficult.
The SHA and crypt() formats are insecure by today's standards.
RESTRICTIONS
On the Windows platform, passwords hashed with htdbm are limited to no more than 255 characters in
length. Longer passwords will be truncated to 255 characters.
The MD5 algorithm used by htdbm is specific to the Apache software; passwords hashed using it will not be
usable with other Web servers.
Usernames are limited to 255 bytes and may not include the character :.
Apache HTTP Server 2024-04-02 HTDBM(1)