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 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 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 encrypted 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 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.

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 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 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 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 :.