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<title>htdbm - Manipulate DBM password databases</title>

<summary>

<p><code>htdbm</code> is used to manipulate the DBM format files used to

store usernames and password for basic authentication of HTTP users via

<module>mod_authn_dbm</module>. See the <program>dbmmanage</program>

documentation for more information about these DBM files.</p>

</summary>

<seealso><program>httpd</program></seealso>

<seealso><program>dbmmanage</program></seealso>

<seealso><module>mod_authn_dbm</module></seealso>

<section id="synopsis"><title>Synopsis</title>

<p><code><strong>htdbm</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

[ -<strong>i</strong> ]

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>filename</var> <var>username</var></code></p>

<p><code><strong>htdbm</strong> -<strong>b</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>filename</var> <var>username</var> <var>password</var></code></p>

<p><code><strong>htdbm</strong> -<strong>n</strong>

[ -<strong>i</strong> ]

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>username</var></code></p>

<p><code><strong>htdbm</strong> -<strong>nb</strong>

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>username</var> <var>password</var></code></p>

<p><code><strong>htdbm</strong> -<strong>v</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

[ -<strong>i</strong> ]

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>filename</var> <var>username</var></code></p>

<p><code><strong>htdbm</strong> -<strong>vb</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

[ -<strong>c</strong> ]

[ -<strong>m</strong> |

-<strong>B</strong> |

-<strong>d</strong> |

-<strong>s</strong> |

-<strong>p</strong> ]

[ -<strong>C</strong> <var>cost</var> ]

[ -<strong>t</strong> ]

[ -<strong>v</strong> ]

<var>filename</var> <var>username</var> <var>password</var></code></p>

<p><code><strong>htdbm</strong> -<strong>x</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

<var>filename</var> <var>username</var></code></p>

<p><code><strong>htdbm</strong> -<strong>l</strong>

[ -<strong>T</strong><var>DBTYPE</var> ]

</code></p>

</section>

<section id="options"><title>Options</title>

<dl>

<dt><code>-b</code></dt>

<dd>Use batch mode; <em>i.e.</em>, get the password from the command line

rather than prompting for it. This option should be used with extreme care,

since <strong>the password is clearly visible</strong> on the command

line. For script use see the <code>-i</code> option.</dd>

<dt><code>-i</code></dt>

<dd>Read the password from stdin without verification (for script usage).</dd>

<dt><code>-c</code></dt>

<dd>Create the <var>passwdfile</var>. If <var>passwdfile</var> already

exists, it is rewritten and truncated. This option cannot be combined with

the <code>-n</code> option.</dd>

<dt><code>-n</code></dt>

<dd>Display the results on standard output rather than updating a

database. This option changes the syntax of the command line, since the

<var>passwdfile</var> argument (usually the first one) is omitted. It

cannot be combined with the <code>-c</code> option.</dd>

<dt><code>-m</code></dt>

<dd>Use MD5 encryption for passwords. On Windows and Netware, this is

the default.</dd>

<dt><code>-B</code></dt>

<dd>Use bcrypt encryption for passwords. This is currently considered to

be very secure.</dd>

<dt><code>-C</code></dt>

<dd>This flag is only allowed in combination with <code>-B</code> (bcrypt

encryption). It sets the computing time used for the bcrypt algorithm

(higher is more secure but slower, default: 5, valid: 4 to 31).</dd>

<dt><code>-d</code></dt>

<dd>Use <code>crypt()</code> encryption for passwords. The default on all

platforms but Windows and Netware. Though possibly supported by

<code>htdbm</code> on all platforms, it is not supported by the

<program>httpd</program> server on Windows and Netware.

This algorithm is <strong>insecure</strong> by today's standards.</dd>

<dt><code>-s</code></dt>

<dd>Use SHA encryption for passwords. Facilitates migration from/to Netscape

servers using the LDAP Directory Interchange Format (ldif).

This algorithm is <strong>insecure</strong> by today's standards.</dd>

<dt><code>-p</code></dt>

<dd>Use plaintext passwords. Though <code>htdbm</code> will support

creation on all platforms, the <program>httpd</program> daemon will

only accept plain text passwords on Windows and Netware.</dd>

<dt><code>-l</code></dt>

<dd>Print each of the usernames and comments from the database on

stdout.</dd>

<dt><code>-v</code></dt>

<dd>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.</dd>

<dt><code>-x</code></dt>

<dd>Delete user. If the username exists in the specified DBM file, it

will be deleted.</dd>

<dt><code>-t</code></dt>

<dd>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.</dd>

<dt><code><var>filename</var></code></dt>

<dd>The filename of the DBM format file. Usually without the extension

<code>.db</code>, <code>.pag</code>, or <code>.dir</code>. If

<code>-c</code> is given, the DBM file is created if it does not already

exist, or updated if it does exist.</dd>

<dt><code><var>username</var></code></dt>

<dd>The username to create or update in <var>passwdfile</var>. If

<var>username</var> does not exist in this file, an entry is added. If it

does exist, the password is changed.</dd>

<dt><code><var>password</var></code></dt>

<dd>The plaintext password to be encrypted and stored in the DBM file.

Used only with the <code>-b</code> flag.</dd>

<dt><code>-T<var>DBTYPE</var></code></dt>

<dd>Type of DBM file (SDBM, GDBM, DB, or "default").</dd>

</dl>

</section>

<section id="bugs"><title>Bugs</title>

<p>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 <var>filename</var> is the same format that

<code>htdbm</code> expects to see. <code>htdbm</code> 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.</p>

<p>One can usually use the <code>file</code> program supplied with most

Unix systems to see what format a DBM file is in.</p>

</section>

<section id="exit"><title>Exit Status</title>

<p><code>htdbm</code> returns a zero status ("true") if the username and

password have been successfully added or updated in the DBM File.

<code>htdbm</code> returns <code>1</code> if it encounters some problem

accessing files, <code>2</code> if there was a syntax problem with the

command line, <code>3</code> if the password was entered interactively and

the verification entry didn't match, <code>4</code> if its operation was

interrupted, <code>5</code> if a value is too long (username, filename,

password, or final computed record), <code>6</code> if the username

contains illegal characters (see the <a href="#restrictions">Restrictions

section</a>), and <code>7</code> if the file is not a valid DBM password

file.</p>

</section>

<section id="examples"><title>Examples</title>

<example>

htdbm /usr/local/etc/apache/.htdbm-users jsmith

</example>

<p>Adds or modifies the password for user <code>jsmith</code>. 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 <code>crypt()</code> routine will be used. If the file does not

exist, <code>htdbm</code> will do nothing except return an error.</p>

<example>

htdbm -c /home/doe/public_html/.htdbm jane

</example>

<p>Creates a new file and stores a record in it for user <code>jane</code>.

The user is prompted for the password. If the file exists and cannot be

read, or cannot be written, it is not altered and <code>htdbm</code>

will display a message and return an error status.</p>

<example>

htdbm -mb /usr/web/.htdbm-all jones Pwd4Steve

</example>

<p>Encrypts the password from the command line (<code>Pwd4Steve</code>)

using the MD5 algorithm, and stores it in the specified file.</p>

</section>

<section id="security"><title>Security Considerations</title>

<p>Web password files such as those managed by <code>htdbm</code> should

<em>not</em> be within the Web server's URI space -- that is, they should

not be fetchable with a browser.</p>

<p>The use of the <code>-b</code> option is discouraged, since when it is

used the unencrypted password appears on the command line.</p>

<p>When using the <code>crypt()</code> 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.</p>

<p>The SHA encryption format does not use salting: for a given password,

there is only one encrypted representation. The <code>crypt()</code> and

MD5 formats permute the representation by prepending a random salt string,

to make dictionary attacks against the passwords more difficult.</p>

<p>The SHA and <code>crypt()</code> formats are insecure by today's

standards.</p>

</section>

<section id="restrictions"><title>Restrictions</title>

<p>On the Windows platform, passwords encrypted with

<code>htdbm</code> are limited to no more than <code>255</code>

characters in length. Longer passwords will be truncated to 255

characters.</p>

<p>The MD5 algorithm used by <code>htdbm</code> is specific to the Apache

software; passwords encrypted using it will not be usable with other Web

servers.</p>

<p>Usernames are limited to <code>255</code> bytes and may not include the

character <code>:</code>.</p>

</section>

</manualpage>