Provided by: apache2-utils_2.4.57-2ubuntu2.5_amd64 
NAME
htpasswd - Manage user files for basic authentication
SYNOPSIS
htpasswd [ -c ] [ -i ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -D ] [ -v ] passwdfile
username
htpasswd -b [ -c ] [ -m | -B | -d | -s | -p ] [ -C cost ] [ -D ] [ -v ] passwdfile
username password
htpasswd -n [ -i ] [ -m | -B | -d | -s | -p ] [ -C cost ] username
htpasswd -nb [ -m | -B | -d | -s | -p ] [ -C cost ] username password
SUMMARY
htpasswd is used to create and update the flat-files used to store usernames and password
for basic authentication of HTTP users. If htpasswd cannot access a file, such as not
being able to write to the output file or not being able to read the file in order to
update it, it returns an error status and makes no changes.
Resources available from the Apache HTTP server can be restricted to just the users listed
in the files created by htpasswd. This program can only manage usernames and passwords
stored in a flat-file. It can encrypt and display password information for use in other
types of data stores, though. To use a DBM database see dbmmanage or htdbm.
htpasswd encrypts passwords using either bcrypt, a version of MD5 modified for Apache,
SHA1, or the system's crypt() routine. Files managed by htpasswd may contain a mixture of
different encoding types of passwords; some user records may have bcrypt or MD5-encrypted
passwords while others in the same file may have passwords encrypted with crypt().
This manual page only lists the command line arguments. For details of the directives
necessary to configure user authentication in httpd see the Apache manual, which is part
of the Apache distribution or can be found at http://httpd.apache.org/.
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. Available in 2.4.4
and later.
-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 file. This is useful
for generating password records acceptable to Apache for inclusion in non-text data
stores. 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. This is the default (since version 2.2.18).
-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 17).
-d Use crypt() encryption for passwords. This is not supported by the httpd server on
Windows and Netware. This algorithm limits the password length to 8 characters.
This algorithm is insecure by today's standards. It used to be the default
algorithm until version 2.2.17.
-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 htpasswd will support creation on all platforms,
the httpd daemon will only accept plain text passwords on Windows and Netware.
-D Delete user. If the username exists in the specified htpasswd file, it will be
deleted.
-v Verify password. Verify that the given password matches the password of the user
stored in the specified htpasswd file. Available in 2.4.5 and later.
passwdfile
Name of the file to contain the user name and password. If -c is given, this file
is created if it does not already exist, or rewritten and truncated 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 file. Only used with the
-b flag.
EXIT STATUS
htpasswd returns a zero status ("true") if the username and password have been
successfully added or updated in the passwdfile. htpasswd 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 password file.
EXAMPLES
htpasswd /usr/local/etc/apache/.htpasswd-users jsmith
Adds or modifies the password for user jsmith. The user is prompted for the password. The
password will be encrypted using the modified Apache MD5 algorithm. If the file does not
exist, htpasswd will do nothing except return an error.
htpasswd -c /home/doe/public_html/.htpasswd 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 htpasswd will display a message and return an error status.
htpasswd -db /usr/web/.htpasswd-all jones Pwd4Steve
Encrypts the password from the command line (Pwd4Steve) using the crypt() algorithm, and
stores it in the specified file.
SECURITY CONSIDERATIONS
Web password files such as those managed by htpasswd should not be within the Web server's
URI space -- that is, they should not be fetchable with a browser.
This program is not safe as a setuid executable. Do not make it setuid.
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 htpasswd are limited to no more than 255
characters in length. Longer passwords will be truncated to 255 characters.
The MD5 algorithm used by htpasswd 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 :.
The cost of computing a bcrypt password hash value increases with the number of rounds
specified by the -C option. The apr-util library enforces a maximum number of rounds of 17
in version 1.6.0 and later.