HTDBM(1) htdbm HTDBM(1)
htdbm - Manipulate DBM password databases
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 ]
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.
-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
-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 encryption for passwords. On Windows and Netware, this is the default.
-B Use bcrypt encryption for passwords. This is currently considered to be very secure.
-C This flag is only allowed in combination with -B (bcrypt encryption). 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() encryption 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 encryption 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 pass-
word 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.
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.
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.
The plaintext password to be encrypted and stored in the DBM file. Used only with the -b flag.
Type of DBM file (SDBM, GDBM, DB, or "default").
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.
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 inter-
actively and the verification entry didn't match, 4 if its operation was interrupted, 5 if a value is too long (username, filename, pass-
word, 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.
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
encrypted 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.
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 unencrypted 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 encryption format does not use salting: for a given password, there is only one encrypted representation. The crypt() and MD5 for-
mats 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.
On the Windows platform, passwords encrypted 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 encrypted 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 2012-12-12 HTDBM(1)