Apache Module mod_auth
Summary
This module allows the use of HTTP Basic Authentication to
restrict access by looking up users in plain text password and
group files. Similar functionality and greater scalability is
provided by mod_auth_dbm. HTTP Digest
Authentication is provided by mod_auth_digest.
Setting the AuthAuthoritative directive
explicitly to Off allows for both authentication and
authorization to be passed on to lower level modules (as defined in the
modules.c files) if there is no userID
or rule matching the supplied userID. If there is a
userID and/or rule specified; the usual password and access checks
will be applied and a failure will give an "Authentication Required"
reply.
So if a userID appears in the database of more than one module;
or if a valid Require
directive applies to more than one module; then the first module
will verify the credentials; and no access is passed on;
regardless of the AuthAuthoritative setting.
A common use for this is in conjunction with one of the
database modules; such as mod_auth_dbm,
mod_auth_msql, and mod_auth_anon.
These modules supply the bulk of the user credential checking; but
a few (administrator) related accesses fall through to a lower
level with a well protected AuthUserFile.
By default control is not passed on and an unknown userID or
rule will result in an "Authentication Required" reply. Not setting
it thus keeps the system secure and forces an NCSA compliant
behaviour.
Security
Do consider the implications of allowing a user to allow
fall-through in his .htaccess file; and verify that this is really
what you want; Generally it is easier to just secure a single
.htpasswd file, than it is to secure a database such as mSQL.
Make sure that the AuthUserFile and the AuthGroupFile are stored outside the document tree of
the web-server; do not put them in the directory that they
protect. Otherwise, clients will be able to download the AuthUserFile and the AuthGroupFile.
The AuthGroupFile directive sets the
name of a textual file containing the list of user groups for user
authentication. File-path is the path to the group
file. If it is not absolute, it is treated as relative to the ServerRoot.
Each line of the group file contains a groupname followed by a
colon, followed by the member usernames separated by spaces.
Example:
mygroup: bob joe anne
Note that searching large text files is very
inefficient; AuthDBMGroupFile provides a much better performance.
Security
Make sure that the AuthGroupFile is
stored outside the document tree of the web-server; do not
put it in the directory that it protects. Otherwise, clients may
be able to download the AuthGroupFile.
The AuthUserFile directive sets the name
of a textual file containing the list of users and passwords for
user authentication. File-path is the path to the user
file. If it is not absolute (i.e., if it doesn't begin
with a slash), it is treated as relative to the ServerRoot.
Each line of the user file contains a username followed by
a colon, followed by the encrypted password. If the same user
ID is defined multiple times, mod_auth will
use the first occurrence to verify the password.
The utility htpasswd
which is installed as part of the binary distribution, or which
can be found in src/support, is used to maintain
this password file. See the man
page for more details. In short:
Create a password file Filename with
username as the initial ID. It will prompt for the
password:
htpasswd -c Filename username
Add or modify username2 in the password file
Filename:
htpasswd Filename username2
Note that searching large text files is very
inefficient; AuthDBMUserFile should be used
instead.
Security
Make sure that the AuthUserFile is
stored outside the document tree of the web-server. Do
not put it in the directory that it protects.
Otherwise, clients may be able to download the
AuthUserFile.
