HTDBM(1) Apache HTTP Server HTDBM(1)
htdbm htdbm
2024-04-02
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.
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-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
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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.
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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
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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
:.
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