Linux Tutorial - Apache Web Login Authentication:

Apache authentication and autorization Intro:

Apache authentication can be configured to require web site visitors to login with a user id and password. This is different than adding a login form on a web page and creating your own authentication. This tutorial describes the various methods available for authentication with Apache and its' configuration. Login protection is applied to the web pages stored in a directory. The login dialog box which requests the user id and password is provided by the web browser at the request of Apache. Apache allows the configuration to be entered in its' configuration files (i.e. main configuration file /etc/httpd/conf/httpd.conf, supplementary configuration files /etc/httpd/conf.d/component.conf or in a file which resides within the directory to be password protected. Five forms of authentication are detailed here: Apache password file authentication, digest file authentication, LDAP, NIS and MySQL.

Apache authentication methods using local files to store passwords, have no association with system user accounts. If using LDAP or NIS for system login authentication, its use can be extended to support Apache web site logins.

Terms:

Authentication: Prove it is you. Authenticate the login by requiring a password only the user would know.
Authorization: Only certain users or members of a privaleged group are allowed.

Typically Authentication or Authentication and Authorization are required for access.

Apache configuration files: (refered to generically in this tutorial as httpd.conf or reside as the file .htpasswd, in the directory being protected.)

Red Hat / Fedora Core / CentOS: /etc/httpd/conf/httpd.conf or /etc/httpd/conf.d/application.conf
Novell SuSE: /etc/apache2/httpd.conf or /etc/apache2/conf.d/application.conf
Ubuntu (dapper 6.06) / Debian: /etc/apache2/apache2.conf or /etc/apache2/conf.d/application.conf

Apache password file authentication:

Directory protection using .htaccess and .htpasswd

This tutorial applies to Apache based web servers. It requires:

Editing the server configuration file (httpd.conf) to enable/allow a directory structure on the server to be password protected. Basically the default <Directory> access permission statement need modification.
The creation and addition of two files specifying the actual logins and passwords. (.htaccess and .htpasswd)

Use this sparingly because Apache will have to check all directories and subdirectories specified in the configuration file for the existence of the .htaccess file adding to a servers latency.

When trying to access a file in a protected directory, the user will be presented with a window (dialog box) requesting a username and password. This protection applies to all sub-directories. Other .htaccess files in sub directories may respecify access rules.

Apache authentication uses the modules mod_auth and mod_access.

Apache configuration file:

File: /etc/httpd/conf/httpd.conf (older systems used access.conf)

Default: This disables the processing of .htaccess files for the system.

     <Directory />
     AllowOverride None
     </Directory>

or for a specified directory:

<Directory /home/domain/public_html>
     AllowOverride None
</Directory>

Change to and/or specify directory to protect:

<Directory /home/domain/public_html/membersonly>
     AllowOverride All
</Directory>

<Directory /home/domain/public_html/membersonly>
     AllowOverride AuthConfig
</Directory>

AllowOverride parameters: AuthConfig FileInfo Indexes Limits Options

The name of the "distributed" and user controlled configuration file .htaccess is defined with the directive: (default shown)

 AccessFileName .htaccess

Password protection by a single login:

Password files:

Create the directory you want to password protect (example: membersonly)
Create a file /home/domain/public_html/membersonly/.htaccess in that director that looks something like this:
```
     AuthName "Add your login message here."
     AuthType Basic
     AuthUserFile /home/domain/public_html/membersonly/.htpasswd
     AuthGroupFile /dev/null
     require user name-of-user
          
```
In this case the "name-of-user" is the login name you wish to use for accessing the web site.
[Pitfall] The literature is full of examples of the next method but I never got it to work.

One can use Apache directives to specify access and restriction:
```
     AuthName "Add your login message here."
     AuthType Basic
     AuthUserFile /home/domain/public_html/membersonly/.htpasswd
     AuthGroupFile /dev/null
     <Limit GET POST>
     require user name-of-user
     </Limit>
         
```
Also see: List of Apache directives. If an incorrect directive is used in the .htaccess file it will result in a server error. Check your log files: /var/log/httpd/error_log.
The name of the access file .htaccess is specified by the httpd.conf directive AccessFileName.

Create (or clobber if it already exists) the password file /home/domain/public_html/membersonly/.htpasswd using the program htpasswd:

         htpasswd -c .htpasswd name-of-user

Add a new user to the existing password file:

         htpasswd .htpasswd name-of-user

Man page: htpasswd

Example file: .htpasswd

user1:KgvCSeExtS4kM
USER1:KgvCSeExtS4kM
User1:KgvCSeExtS4kM

Password file protection, ownership and SELinux attributes:

File privileges: chmod ug+rw .htpasswd
File ownership: chown apache.apache .htpasswd
SELinux file attributes: chcon -R -h -u system_u -r object_r -t httpd_config_t .htpasswd

This is required so that the Apache web server can access the password file.

Flexible password protection by group access permissions:

This example differs from the previous example in that it allows for greater control and flexibility by using groups.

Password files:

Create a file .htgroup in that directory that contains the groupname and list of users:
```
      member-users: user1 user2 user3 ... etc
    
```
Where member-users is the name of the group.

Modify .htaccess in the membersonly directory so it looks something like:

      AuthName "Add your login message here."
      AuthType Basic
      AuthUserFile /home/domain/public_html/membersonly/.htpasswd
      AuthGroupFile /home/domain/public_html/membersonly/.htgroup
      require group member-users

Create the password file .htpasswd using the program htpasswd for each user as above. You don't need the -c option if you are using the same .htpasswd file. (-c is only to create a new file)
```
         htpasswd -c /home/domain/public_html/membersonly/.htpasswd user1
         htpasswd /home/domain/public_html/membersonly/.htpasswd user2
        
```

Restrict access based on domain or IP address:

Allow specified domain to access site:

Order deny, allow
Deny from all
Allow from allowable-domain.com
Allow from XXX.XXX.XXX
Deny from  evil-domain.com

Specify first three (or one, or two, ...) octets of IP address defining allowable domain.

Placing Authentication directives in httpd.conf exclusively instead of using .htaccess:

The purpose of using the "distributed configuration file" .htaccess is so that users may control authentication. It can also be set in the Apache configuration file httpd.conf WITHOUT using the .htaccess file. This can improve server performance as the server will not have to look for the .htaccess file in each subdirectory.

File: httpd.conf (portion)

    ..
    ...

     <Directory /home/domain/public_html/membersonly>
     AllowOverride AuthConfig
     AuthName "Add your login message here."
     AuthType Basic
     AuthUserFile /home/domain/public_html/membersonly/.htpasswd
     AuthGroupFile /dev/null
     require user name-of-user
     </Directory>

    ...
    ..

Perl CGI Script to Modify User Passwords:

This allows users to manage / change their own passwords.

Use the Perl CGI script htpasswd.pl [cache]

Edit location of Perl .i.e.: /usr/bin/perl
Not /usr/local/bin/perl
Edit the script to specify location of the password file i.e. /var/www/PasswordDir/.htpasswd
SELinux users must add the correct attribute i.e. chcon -R -h -t httpd_sys_content_t /var/www/PasswordDir

The password file must be located in a directory where CGI is allowed to modify files.
File: httpd.conf (portion)

    ..
    ...

<Directory "/var/www/PasswordDir">
    Options -Indexes
    AllowOverride None
    Options None
    Order allow,deny
    Allow from all
</Directory>
    ...
    ..

Using Digest File for Apache Authentication:

This method authenticates a user login using Apache 2.0 on Linux. The logins have no connection to user accounts.

<Location /home/domain/public_html/membersonly>
   AuthType Digest
   AuthNAme "Members Only Area"
   AuthDigestDomain /home/domain/public_html/membersonly
   AuthDigestFile /etc/httpd/conf/digestpw
   require valid-user
</Location>

For more on digest authentication see:

Using LDAP for Apache Authentication:

This method authenticates using Apache 2.0/2.2 and the LDAP authentication modules on Linux (supplied by default with most Linux distros) and an LDAP server. LDAP can be used to authenticate user accounts on Linux and other computer systems as well as web site logins.
Also see YoLinux TUTORIAL: LDAP system authentication.

Try this out with your Apache server authenticating to our open LDAP server using our Three Stooges example.

Apache LDAP modules:

Note that the following configurations work if the LDAP modules are enabled:

Apache 2.0 (Red Hat Enterprise 4/CentOS4): mod_ldap, mod_auth_ldap
Apache 2.2 (Red Hat Enterprise 5/CentOS 5): mod_ldap, mod_authnz_ldap

These are turned on by default. See /etc/httpd/conf/httpd.conf

Apache 2.0:

LoadModule ldap_module modules/mod_ldap.so
LoadModule auth_ldap_module modules/mod_auth_ldap.so

Apache 2.2:

LoadModule ldap_module modules/mod_ldap.so
LoadModule authnz_ldap_module modules/mod_authnz_ldap.so

Apache Authentication Configuration:

Apache authentication configuration is version dependent.

# Apache HTTPd 2.2
# Apache HTTPd 2.0

Apache HTTPd 2.2:

Authenticate using Apache httpd 2.2 AuthzLDAP:

User Authentication:

File: httpd.conf (portion)

..
...

<Directory /var/www/html>
   AuthType Basic
   AuthName "Stooges Web Site: Login with user id"
   AuthBasicProvider ldap
   AuthzLDAPAuthoritative on
   AuthLDAPURL ldap://ldap.your-domain.com:389/o=stooges?uid?sub
   AuthLDAPBindDN "cn=StoogeAdmin,o=stooges"
   AuthLDAPBindPassword secret1
   require ldap-user lary curley moe joe bob mary 
</Directory>
...
..

There are two configurations for the directive AuthzLDAPAuthoritative:

AuthzLDAPAuthoritative on (default)

AuthzLDAPAuthoritative on

...

require ldap-user lary curley moe joe bob mary

AuthzLDAPAuthoritative off

AuthzLDAPAuthoritative off

...

require valid-user

This configuration allows a waterfall of other authentication methods to be employed along side LDAP.

Group Authentication:

LDAP LDIF file: (part of our stooges example)

dn: cn=users,ou=group,o=stooges
cn: users
objectClass: top
objectClass: posixGroup
gidNumber: 100
memberUid: larry
memberUid: moe

Apache Configuration:

...

<Directory /var/www/html>
   Order deny,allow
   Deny from All
   AuthType Basic
   AuthName "Stooges Web Site: Login with user id"
   AuthBasicProvider ldap
   AuthzLDAPAuthoritative on
   AuthLDAPURL ldap://ldap.your-domain.com:389/o=stooges?uid?sub
   AuthLDAPBindDN "cn=StoogeAdmin,o=stooges"
   AuthLDAPBindPassword secret1
   AuthLDAPGroupAttribute memberUid
   AuthLDAPGroupAttributeIsDN off
   Require ldap-group cn=users,ou=group,o=stooges
   Require ldap-attribute gidNumber=100
   Satisfy any
</Directory>
...

Note:

Allow users (LDAP attribute: memberUid) in group gidNumber: 100 of objectClass: posixGroup which match to the login uid, authentication approval.
The directive AuthLDAPGroupAttribute identifies the attribute to match with the login uid.
AuthLDAPGroupAttributeIsDN:
- on (default): Use DN (Distinguished name) cn=Moe Howard,ou=MemberGroupA,o=stooges
- off: Use username moe
Multiple Require ldap-group ... statements may be included to allow multiple groups.
Multiple Require ldap-attribute ... statements may be included to allow multiple groups.
The directive Satisfy any is required if testing multiple conditions. Only one positive in any of the conditions is required to authenticate. Thus you can combine the following authorization schemes as well:
- Require ldap-user
- Require ldap-dn
- Require ldap-attribute
- Require ldap-filter

Apache HTTPd 2.0:

Authenticate to an Open LDAP server. (No bind name/password required to access LDAP server)

File: httpd.conf (portion)

..
...

<Directory /var/www/html>
   AuthType Basic
   AuthName "Stooges Web Site: Login with email address"
   AuthLDAPURL ldap://ldap.yolinux.com:389/o=stooges?mail
   require valid-user
</Directory>
...
..

or create the file /var/www/html/.htaccess

AuthName "Stooges Web Site: Login with email address"
AuthType Basic
AuthLDAPURL ldap://ldap.your-domain.com:389/o=stooges?mail
require valid-user

Point your browser to http://localhost/
Login with the user id "LFine@isp.com" and password "larrysecret".
You will be asked to use a user id (email address) and password to enter the site.

Bind with a bind DN: (password protected LDAP repository)

File: httpd.conf (portion)

..
...

<Directory /var/www/html>
   AuthType Basic
   AuthName "Stooges Web Site: Login with email address"
   AuthLDAPEnabled on
   AuthLDAPURL ldap://ldap.your-domain.com:389/o=stooges?mail
   AuthLDAPBindDN "cn=StoogeAdmin,o=stooges"
   AuthLDAPBindPassword secret1
   require valid-user
</Directory>
...
..

Examples:

require valid-user: Allow all users if authentication (password) is correct.
require user greg phil bob: Allow only greg phil bob to login.
require group accounting: Allow only users in group "accounting" to authenticate.

For this LDAP authentication example to work, configure your LDAP server with our YoLinux Three Stooges example and set the password in the /etc/openldap.slapd.conf file.

This example specified the use of the email address as a login id. If using user id's specify:

AuthLDAPURL ldap://ldap.your-domain.com:389/o=stooges?uid

Concurrent File and LDAP authentication:

Apache can use both File and LDAP authentication concurently. This is sometimes required to run cron jobs with a login where you do not want to use a system login or login managed by a directory server in another department.

<Directory /ABC>
   Order deny,allow
   Deny from All
   AuthType Basic
   AuthBasicProvider file ldap
   AuthName "Directory services login"
   AuthBasicAuthoritative  off
   AuthUserFile /srv/htpasswd
   AuthGroupFile /dev/null
   AuthzLDAPAuthoritative off
   AuthLDAPURL "ldap://ldap.megacorp.com:389/ou=person,o=megacorp.com,c=us?uid?sub"
#  This user created for local cron jobs. It is not a system user and allows
#  the cron job to perform its task.
#  This user is not in the LDAP directory but in the password file /srv/htpasswd
   Require user cronuserjobx
   Require ldap-user usera userb
</Directory>

Note:

AuthBasicProvider file ldap - Check password "file" authentication then LDAP
AuthBasicAuthoritative off - Allows fall back to another auth scheme, in this case LDAP
AuthzLDAPAuthoritative off - Allows fall back to other auth scheme besides LDAP, in this case file

Debugging Apache Authentication:

Set LogLevel debug when debugging authentication. This will log all the LDAP connection events and the LDAP attributes requested.

Authenticating with Microsoft Active directory using Microsoft's "Unix services for Windows":

AuthLDAPURL ldap://ldap.your-domain.com:389/ou=Employees,ou=Accounts,dc=sos,dc=com?sAMAccountName?sub Also note that encrypted connections will use the URL prefix "ldaps://" and the added directives:

LDAPTrustedCA directory-path/filename
LDAPTrustedCAType type
Where the "type" is one of:
- DER_FILE: file in binary DER format
- BASE64_FILE: file in Base64 format
- CERT7_DB_PATH: Netscape certificate database file

Restart Apache after editing the configuration file: service httpd restart for configuration changes to take effect.
See /var/log/httpd/error_log for configuration errors.

Links:

YoLinux Tutorial: Configuration of an LDAP server - includes a quick start example using the Three Stooges.
YoLinux Tutorial: Apache web server configuration

Apache documentation:

Apache 2.0:
- mod_ldap
- mod_auth_ldap
Apache 2.2:
- mod_ldap
- mod_authnz_ldap

Other LDAP modules:

Apache LDAP module mod_ldap_userdir (Apache 2.x)
Apache mod_auth_ldap web server module for authentication with Netscape or OpenLDAP servers (HowTo)

Using NIS for Apache Authentication:

This method authenticates using Apache on Linux and an NIS server. The advantage of using NIS, is the comonality of computer system accounts and web site logins. This configuration requires that the system the Apache web server is running on, must be using NIS authentication for system logins.

This requires a NIS server. See the YoLinux.com NIS configuration tutorial.

Requires the Linux RPM package mod_perl and the following Perl modules:

ExtUtils-AutoInstall
Net-NIS
Apache2-AuthenNIS or Apache-AuthenNIS

The version of Apache determines which Perl modules to use:

Apache 2.2 (RHEL5, CentOS5, FC6): Use the Perl module Apache2-AuthenNIS.
Apache 2.0 (RHEL4, CentOS4, FC3): Use the Perl module Apache-AuthenNIS.

Download / Install Perl modules:

RedHat:
- Download "perl-ExtUtils-AutoInstall" as an RPM from EPEL: perl-ExtUtils-AutoInstall-0.xx-x.x.elx.noarch.rpm
  Install: rpm -ivh perl-ExtUtils-AutoInstall-0.xx-x.x.elx.noarch.rpm
Ubuntu:
- Install: sudo apt-get install libextutils-autoinstall-perl
Net-NIS: (CPAN)
- tar xzf Net-NIS-0.xx.tar.gz
- cd Net-NIS-0.xx/
- perl Makefile.PL
- make
- make install

Apache(2)-AuthenNIS:

Apache 2.2	Apache 2.0
Apache2-AuthenNIS: (CPAN) tar xzf Apache2-AuthenNIS-0.15.tar.gz cd Apache2-AuthenNIS-0.15 perl Makefile.PL make make install	Apache-AuthenNIS: (CPAN) tar xzf Apache-AuthenNIS-0.13.tar.gz cd Apache-AuthenNIS-0.13 perl Makefile.PL make make install

Or install from CPAN via the internet:

perl -MCPAN -e shell
(Answer no)
install ExtUtils::AutoInstall
install Net::NIS
install Apache2::AuthenNIS (or Apache::AuthenNIS)
quit

Test Perl module:

File: testApache2AuthenNIS.pl

#!/usr/bin/perl
BEGIN{push @INC, "/usr/lib/perl5/site_perl/5.8.8/Apache2";}
eval "use Apache2::AuthenNIS"; $hasApacheAuth = $@ ? 0 : 1;
printf "Apache2::AuthenNIS". ($hasApacheAuth ?  "" : " not") . " installed";
printf "\n";

Test: [root]# ./testApache2AuthenNIS.pl

Good: Apache2::AuthenNIS installed
Not good: Apache2::AuthenNIS not installed

File: testApacheAuthenNIS.pl

#!/usr/bin/perl
BEGIN{push @INC, "/usr/lib/perl5/site_perl/5.8.5/Apache";}
eval "use Apache::AuthenNIS"; $hasApacheAuth = $@ ? 0 : 1;
printf "Apache::AuthenNIS". ($hasApacheAuth ?  "" : " not") . " installed";
printf "\n";

Test: [root]# ./testAuthenNIS.pl

Good: Apache::AuthenNIS installed
Not good: Apache::AuthenNIS not installed

Apache NIS authentication Examples:

require valid-user: Allow all users if authentication (password) is correct.
require user greg phil bob: Allow only greg phil bob to login.
require group accounting: Allow only users in group "accounting" to authenticate.

1) Restric access to NIS authenticated users:

Apache Configuration File: httpd.conf (portion)

..
...

<Directory /home/domain/public_html/membersonly>
    AuthType Basic
    AuthName "Add your login message here."
    PerlAuthenHandler Apache2::AuthenNIS      - or Apache::AuthenNIS
    PerlSetVar AllowAlternateAuth no
    require valid-user
</Directory>

...
..

2) Restrict to listed users greg, phil and bob, but still authenticate to NIS:

Apache Configuration File: httpd.conf (portion)

..
...

<Directory /home/domain/public_html/membersonly>
    AuthType Basic
    AuthName "Add your login message here."
    PerlAuthenHandler Apache2::AuthenNIS      - or Apache::AuthenNIS
    PerlSetVar AllowAlternateAuth no
    require user greg phil bob
</Directory>

...
..

3) Restrict access to NIS members of a specific NIS group:

Apache Configuration File: httpd.conf (portion)

..
...

<Directory /home/domain/public_html/membersonly>
    AuthType Basic
    AuthName "Add your login message here."
    PerlAuthenHandler Apache2::AuthenNIS      - or Apache::AuthenNIS
    PerlAuthzHandler Apache2::AuthzNIS        - or Apache::AuthzNIS
    PerlSetVar AllowAlternateAuth no
    require group accounting
</Directory>

...
..

Note Apache2::AuthzNIS only checks for group membership by group name (not GID). Apache2::AuthenNIS still required to authenticate the user (check password).

Example showing password protection for user web directories:

Apache Configuration File: httpd.conf (portion)

..
...

<IfModule mod_userdir.c>
    UserDir public_html
</IfModule>

<Directory /home/*/public_html>
    AuthType Basic
    AuthName "Add your login message here."
    PerlAuthenHandler Apache2::AuthenNIS      - or Apache::AuthenNIS
    PerlSetVar AllowAlternateAuth no
    require user valid-user

    AllowOverride FileInfo AuthConfig Limit
    Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
    <Limit GET POST OPTIONS>
        Order allow,deny
        Allow from all
    </Limit>
    <LimitExcept GET POST OPTIONS>
        Order deny,allow
        Deny from all
    </LimitExcept>
</Directory>

...
..

Also see YoLinux SysAdmin: Perl Admin

Links:

NIS+ (More secure than NIS):
- Apache::AuthenNISPlus
Group NIS authentication:
- Apache2::AuthzNIS
- Apache::AuthzNIS

Note:

Apache allows further restriction by client IP network address or subnet.
Passwords can also be sent over an encrypted https connection by use of the Apache directive SSLRequireSSL. See Apache SSL/TLS encryption

[Potential Pitfall]: This method of authentication will fail if using "adjunct password maps". This Perl module requires the use of the library call yp_match() which must have access to the encrypted passwords. If "adjunct password maps" are used, then this is not accessible to processes other than root thus the web server daemon process apache will not be able to access the data required. Test your system using the command ypcat passwd | head. If the second field is prefixed with "##", then this perl module will not work. If the second field is an encrypted password, then this perl module can work.

CGI to allow users to modify their NIS Passwords:

For those users who get a shell of /sbin/nologin, the "cgipaf" web interface is ideal for user management of NIS passwords. Cgipaf uses PHP, cgi (written in C) and your system PAM authentication (or /etc/passwd, /etc/shadow files). Cgipaf also can manage mail accounts using procmail.

Download from http://www.wagemakers.be/english/programs/cgipaf

Installation/configuration:

tar xf cgipaf-1.3.1.tar.gz
cd cgipaf-1.3.1/
./configure --bindir=/var/www/cgi-bin --datadir=/srv/cgipaf --sysconfigdir=/etc/cgipaf --prefix=/opt
Note: nothing ends up in /opt
make
make install
cd /srv/cgipaf
ln -s cgipasswd.php index.php

File: /etc/httpd/conf.d/cgipaf.conf (Red Hat style systems)

Alias /NIS/ "/srv/cgipaf/"

<Directory "/srv/cgipaf">
  SSLRequireSSL
  Options Indexes FollowSymLinks
  AllowOverride None
  Order allow, deny
  Allow from all
</Directory>

Note the Apache 2 directive "SSLRequireSSL" will only allow https encrypted access. This is important when managing passwords over the web.

The PHP pages reside in /srv/cgipaf/. The compiled C cgi will reside in /var/www/cgi-bin. The configuration file will be /etc/cgipaf/cgipaf.conf.

See the web page at http://localhost/NIS/

Using a MySQL database for Apache Authentication:

Two Apache modules are available for database authentication:

MySQL: mod_auth_mysql (This tutorial)
- Red Hat RPM package: mod_auth_mysql
- SuSE RPM package: apache2-mod_auth_mysql
DBM database file: mod_auth_dbm
(Fast even for 1000's of users.)

Apache Configuration:

Red Hat: /etc/httpd/conf/httpd.conf or /etc/httpd/conf.d/application.conf
SuSE: /etc/apache2/httpd.conf or /etc/apache2/conf.d/application.conf

    ..
    ...

     <Directory /home/domain/public_html/membersonly>
     AuthType Basic
     AuthName "Add your login message here."
     AuthMySQLHost localhost
     AuthMySQLUser db_user
     AuthMySQLPassword db_password
     AuthMySQLDB database_name_used_for_authentication
     AuthMysqlUserTable  http_auth
     AuthMySQLPwEncryption none
     AuthMySQLEnable on
     require valid-user
     </Directory>

    ...
    ..

Examples:

require valid-user: Allow all users if authentication (password) is correct.
require user greg phil bob: Allow only greg phil bob to login.
require group accounting: Allow only users in group "accounting" to authenticate.

Directives:

Directive	Description
AuthMySQLEnable On	If 'Off', MySQL authentication will pass on the authentication job to the other authentication modules i.e password files.
AuthMySQLHost host_name	Name of MySQL Database hosr. i.e. 'localhost'
AuthMySQLPort TCP_Port_number	Port number of MySQL Database. Default: 3306
AuthMySQLDB database_name	Name of MySQL Database.
AuthMySQLUser user_id	MySQL Database login id.
AuthMySQLPassword user_password	MySQL Database login password. Plain text.
AuthMySQLUserTable user_table_name	Name of MySQL Databse table in the database which holds the user name and passwords.
AuthMySQLGroupTable group_table_name	Databse table holding group info.
AuthMySQLNameField user_field_name	If not using default field name 'user_name', then specify. Not case sensitive id CHAR or VARCHAR.
AuthMySQLPasswordField password_field_name	If not using default field name 'user_passwd', then specify. Passwords are case sensitive.
AuthMySQLGroupField group_field_name	If not using default field name 'groups', then specify.
AuthMySQLNoPasswd Off	Off: Passwords can be null (''). On: password must be specified.
AuthMySQLPwEncryption none	Options: none, crypt, scrambled (MySQL password encryption), md5, aes, sha. If you are going to use plain-text passwords for mysql authentication, you must include this directive with the argument "none".
AuthMySQLSaltField salt_string mysql_column_name	Salt field to be used for crypt and aes.
AuthMySQLAuthoritative on	Authenticate using other authentication modules after the user is successfully authenticated by the MySQL auth module. Default on: request is not passed on.
AuthMySQLKeepAlive Off	Off: Close the MySQL link after each authentication request.

MySQL Admin:

mysqladmin -h localhost -u root -ppassword create http_auth
mysql -h localhost -u root -ppassword
mysql> use http_auth
mysql> create table mysql_auth ( user_name char(30) NOT NULL,user_passwd char(60) NOT NULL,user_group char(25),primary key (user_name) );
mysql> insert into mysql_auth values('Fred','supersecret','worker');

Links:

Home page for mod_auth_mysql
Home page for mod_auth_dbm [Apache 1.3] - [Apache 2.0]
YoLinux MySQL tutorial

Here is a trick to incorporate a login and password into a URL. Typicall one would attempt to enter the password protected area of the web site and the user would be confronted with a login dialog box into which one would enter the user id and password. Another option is to enter a URL with the login and password embedded.

    http://login-id:password@UrlOfDomain.com/protectedPath/WebPage.html

Links:

Apache:

Users authentication with .dbmpasswd password file
Apache::AuthenSmb, Apache2::AuthenSmb - Microsoft Active Directory authentication
Apache::AuthenMSAD, Apache2::AuthenMSAD - Samba NT PDC authentication
Apache::AuthenNTLM, Apache2::AuthenNTLM - Microsoft NTLM LAN protocol suported by MS/Internet Explorer. Login/password credentials passed on the web server by IE browser.

Other forms of web authentication:

Facebook Platform authentication - Using OAuth protocol, the Facebook API allows developers to use Javascript, PHP, Python, etc.
IETF OAuth 2.0 Protocol draft
OpenID - decentralized URL based auth
Authentication Server Providers:
- Yahoo OpenID
- Google OpenID
  OpenID for Google Apps API
- Launchpad
- OpenID - two factor auth
API:
- mod_auth_openid - Apache 2
- OpenId4Java
- List of OpenID Libraries - developer interfaces
SAML: Security Assertion Markup Language - XML based authentication
Authentication Server Providers:
- Google SAML

Books:

	"Apache Server Bible 2" by Mohammed J. Kabir ISBN # 0764548212, Hungry Minds This book is very complete covering all aspects in detail. It is not your basic reprint of the apache.org documents like so many others.
	"LDAP System Administration", Gerald Carter ISBN 1565924916, O'Reilly & Associates This book covers the use of OpenLDAP and the integration of services.
	"Managing NFS and NIS", by Hal Stern, Mike Eisler, Ricardo Labiaga ISBN 1565925106, O'Reilly & Associates