10.2. Migrating Apache HTTP Server 1.3 Configuration Files

10.2.1.1. Interface and Port Binding

The BindAddress and Port directives no longer exist; their functionality is now provided by a more flexible Listen directive.

If Port 80 was set in the 1.3 version configuration file, change it to Listen 80 in the 2.0 configuration file. If Port was set to some value other than 80, then append the port number to the contents of the ServerName directive.

For example, the following is a sample Apache HTTP Server 1.3 directive:

Port 123
ServerName www.example.com

To migrate this setting to Apache HTTP Server 2.0, use the following structure:

Listen 123
ServerName www.example.com:123 

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mpm_common.html#listen

• https://httpd.apache.org/docs-2.0/mod/core.html#servername

10.2.1.2. Server-Pool Size Regulation

When the Apache HTTP Server accepts requests, it dispatches child processes or threads to handle them. This group of child processes or threads is known as a server-pool. Under Apache HTTP Server 2.0, the responsibility for creating and maintaining these server-pools has been abstracted to a group of modules called Multi-Processing Modules (MPMs). Unlike other modules, only one module from the MPM group can be loaded by the Apache HTTP Server. There are three MPM modules that ship with 2.0: prefork, worker, and perchild. Currently only the prefork and worker MPMs are available, although the perchild MPM may be available at a later date.

The original Apache HTTP Server 1.3 behavior has been moved into the prefork MPM. The prefork MPM accepts the same directives as Apache HTTP Server 1.3, so the following directives may be migrated directly:

• StartServers

• MinSpareServers

• MaxSpareServers

• MaxClients

• MaxRequestsPerChild

The worker MPM implements a multi-process, multi-threaded server providing greater scalability. When using this MPM, requests are handled by threads, conserving system resources and allowing large numbers of requests to be served efficiently. Although some of the directives accepted by the worker MPM are the same as those accepted by the prefork MPM, the values for those directives should not be transfered directly from an Apache HTTP Server 1.3 installation. It is best to instead use the default values as a guide, then experiment to determine what values work best.

	Important
	To use the worker MPM, create the file /etc/sysconfig/httpd and add the following directive: HTTPD=/usr/sbin/httpd.worker

For more on the topic of MPMs, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mpm.html

10.2.1.3. Dynamic Shared Object (DSO) Support

There are many changes required here, and it is highly recommended that anyone trying to modify an Apache HTTP Server 1.3 configuration to suit version 2.0 (as opposed to migrating the changes into the version 2.0 configuration) copy this section from the stock Apache HTTP Server 2.0 configuration file.

Those who do not want to copy the section from the stock Apache HTTP Server 2.0 configuration should note the following:

• The AddModule and ClearModuleList directives no longer exist. These directives where used to ensure that modules could be enabled in the correct order. The Apache HTTP Server 2.0 API allows modules to specify their ordering, eliminating the need for these two directives.

• The order of the LoadModule lines are no longer relevant in most cases.

• Many modules have been added, removed, renamed, split up, or incorporated into others.

• LoadModule lines for modules packaged in their own RPMs (mod_ssl, php, mod_perl, and the like) are no longer necessary as they can be found in their relevant files within the /etc/httpd/conf.d/ directory.

• The various HAVE_XXX definitions are no longer defined.

	Important
	If modifying the original file, note that it is of paramount importance that the httpd.conf contains the following directive: Include conf.d/*.conf Omission of this directive results in the failure of all modules packaged in their own RPMs (such as mod_perl, php, and mod_ssl).

10.2.1.4. Other Global Environment Changes

The following directives have been removed from Apache HTTP Server 2.0's configuration:

• ServerType — The Apache HTTP Server can only be run as ServerType standalone making this directive irrelevant.

• AccessConfig and ResourceConfig — These directives have been removed as they mirror the functionality of the Include directive. If the AccessConfig and ResourceConfig directives are set, replace them with Include directives.

  To ensure that the files are read in the order implied by the older directives, the Include directives should be placed at the end of the httpd.conf, with the one corresponding to ResourceConfig preceding the one corresponding to AccessConfig. If using the default values, include them explicitly as conf/srm.conf and conf/access.conf files.

10.2.2.1. UserDir Mapping

The UserDir directive is used to enable URLs such as https://example.com/~bob/ to map to a subdirectory within the home directory of the user bob, such as /home/bob/public_html/. A side-effect of this feature allows a potential attacker to determine whether a given username is present on the system. For this reason, the default configuration for Apache HTTP Server 2.0 disables this directive.

To enable UserDir mapping, change the directive in httpd.conf from:

UserDir disable

to the following:

UserDir public_html

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_userdir.html#userdir

10.2.2.2. Logging

The following logging directives have been removed:

• AgentLog

• RefererLog

• RefererIgnore

However, agent and referrer logs are still available using the CustomLog and LogFormat directives.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_log_config.html#customlog

• https://httpd.apache.org/docs-2.0/mod/mod_log_config.html#logformat

10.2.2.3. Directory Indexing

The deprecated FancyIndexing directive has now been removed. The same functionality is available through the FancyIndexing option within the IndexOptions directive.

The VersionSort option to the IndexOptions directive causes files containing version numbers to be sorted in a more natural way. For example, httpd-2.0.6.tar appears before httpd-2.0.36.tar in a directory index page.

The defaults for the ReadmeName and HeaderName directives have changed from README and HEADER to README.html and HEADER.html.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_autoindex.html#indexoptions

• https://httpd.apache.org/docs-2.0/mod/mod_autoindex.html#readmename

• https://httpd.apache.org/docs-2.0/mod/mod_autoindex.html#headername

10.2.2.4. Content Negotiation

The CacheNegotiatedDocs directive now takes the argument on or off. Existing instances of CacheNegotiatedDocs should be replaced with CacheNegotiatedDocs on.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_negotiation.html#cachenegotiateddocs

10.2.2.5. Error Documents

To use a hard-coded message with the ErrorDocument directive, the message should be enclosed in a pair of double quotation marks ["], rather than just preceded by a double quotation mark as required in Apache HTTP Server 1.3.

For example, the following is a sample Apache HTTP Server 1.3 directive:

ErrorDocument 404 "The document was not found

To migrate an ErrorDocument setting to Apache HTTP Server 2.0, use the following structure:

ErrorDocument 404 "The document was not found"

Note the trailing double quote in the previous ErrorDocument directive example.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/core.html#errordocument

10.2.4.1. The suexec Module

In Apache HTTP Server 2.0, the mod_suexec module uses the SuexecUserGroup directive, rather than the User and Group directives, which is used for configuring virtual hosts. The User and Group directives can still be used in general, but are deprecated for configuring virtual hosts.

For example, the following is a sample Apache HTTP Server 1.3 directive:

<VirtualHost vhost.example.com:80>
    User someone
    Group somegroup
</VirtualHost>

To migrate this setting to Apache HTTP Server 2.0, use the following structure:

<VirtualHost vhost.example.com:80>
    SuexecUserGroup someone somegroup
</VirtualHost>

10.2.4.2. The mod_ssl Module

The configuration for mod_ssl has been moved from the httpd.conf file into the /etc/httpd/conf.d/ssl.conf file. For this file to be loaded, and for mod_ssl to work, the statement Include conf.d/*.conf must be in the httpd.conf file as described in Section 10.2.1.3 Dynamic Shared Object (DSO) Support.

ServerName directives in SSL virtual hosts must explicitly specify the port number.

For example, the following is a sample Apache HTTP Server 1.3 directive:

<VirtualHost _default_:443>
    # General setup for the virtual host
    ServerName ssl.example.name
    ...
</VirtualHost>

To migrate this setting to Apache HTTP Server 2.0, use the following structure:

<VirtualHost _default_:443>
    # General setup for the virtual host
    ServerName ssl.host.name:443
    ...
</VirtualHost>

It is also important to note that both the SSLLog and SSLLogLevel directives have been removed. The mod_ssl module now obeys the ErrorLog and LogLevel directives. Refer to Section 10.5.35 ErrorLog and Section 10.5.36 LogLevel for more information about these directives.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_ssl.html

• https://httpd.apache.org/docs-2.0/vhosts/

10.2.4.3. The mod_proxy Module

Proxy access control statements are now placed inside a <Proxy> block rather than a <Directory proxy:>.

The caching functionality of the old mod_proxy has been split out into the following three modules:

• mod_cache

• mod_disk_cache

• mod_mem_cache

These generally use directives similar to the older versions of the mod_proxy module, but it is advisable to verify each directive before migrating any cache settings.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_proxy.html

10.2.4.4. The mod_include Module

The mod_include module is now implemented as a filter and is therefore enabled differently. Refer to Section 10.2.4 Modules and Apache HTTP Server 2.0 for more about filters.

For example, the following is a sample Apache HTTP Server 1.3 directive:

AddType text/html .shtml
AddHandler server-parsed .shtml

To migrate this setting to Apache HTTP Server 2.0, use the following structure:

AddType text/html .shtml
AddOutputFilter INCLUDES .shtml

Note that the Options +Includes directive is still required for the <Directory> container or in a .htaccess file.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_include.html

10.2.4.5. The mod_auth_dbm and mod_auth_db Modules

Apache HTTP Server 1.3 supported two authentication modules, mod_auth_db and mod_auth_dbm, which used Berkeley Databases and DBM databases respectively. These modules have been combined into a single module named mod_auth_dbm in Apache HTTP Server 2.0, which can access several different database formats. To migrate from mod_auth_db, configuration files should be adjusted by replacing AuthDBUserFile and AuthDBGroupFile with the mod_auth_dbm equivalents, AuthDBMUserFile and AuthDBMGroupFile. Also, the directive AuthDBMType DB must be added to indicate the type of database file in use.

The following example shows a sample mod_auth_db configuration for Apache HTTP Server 1.3:

<Location /private/>
  AuthType Basic
  AuthName "My Private Files"
  AuthDBUserFile /var/www/authdb
  require valid-user
</Location>

To migrate this setting to version 2.0 of Apache HTTP Server, use the following structure:

<Location /private/>
  AuthType Basic
  AuthName "My Private Files"
  AuthDBMUserFile /var/www/authdb
  AuthDBMType DB
  require valid-user
</Location>

Note that the AuthDBMUserFile directive can also be used in .htaccess files.

The dbmmanage Perl script, used to manipulate username and password databases, has been replaced by htdbm in Apache HTTP Server 2.0. The htdbm program offers equivalent functionality and, like mod_auth_dbm, can operate a variety of database formats; the -T option can be used on the command line to specify the format to use.

Table 10-1 shows how to migrate from a DBM-format database to htdbm format using dbmmanage.

The -m and -s options work with both dbmmanage and htdbm, enabling the use of the MD5 or SHA1 algorithms for hashing passwords, respectively.

When creating a new database with htdbm, the -c option must be used.

For more on this topic, refer to the following documentation on the Apache Software Foundation's website:

• https://httpd.apache.org/docs-2.0/mod/mod_auth_dbm.html

10.2.4.6. The mod_perl Module

The configuration for mod_perl has been moved from httpd.conf into the file /etc/httpd/conf.d/perl.conf. For this file to be loaded, and hence for mod_perl to work, the statement Include conf.d/*.conf must be included in httpd.conf as described in Section 10.2.1.3 Dynamic Shared Object (DSO) Support.

Occurrences of Apache:: in httpd.conf must be replaced with ModPerl::. Additionally, the manner in which handlers are registered has been changed.

This is a sample Apache HTTP Server 1.3 mod_perl configuration:

<Directory /var/www/perl>
    SetHandler perl-script
    PerlHandler Apache::Registry
    Options +ExecCGI
</Directory>

This is the equivalent mod_perl for Apache HTTP Server 2.0:

<Directory /var/www/perl>
    SetHandler perl-script
    PerlResponseHandler ModPerl::Registry
    Options +ExecCGI
</Directory>

Most modules for mod_perl 1.x should work without modification with mod_perl 2.x. XS modules require recompilation and may require minor Makefile modifications.

10.2.4.7. The mod_python Module

Configuration for mod_python has moved from httpd.conf to the /etc/httpd/conf.d/python.conf file. For this file to be loaded, and hence for mod_python to work, the statement Include conf.d/*.conf must be in httpd.conf as described in Section 10.2.1.3 Dynamic Shared Object (DSO) Support.

10.2.4.8. PHP

The configuration for PHP has been moved from httpd.conf into the file /etc/httpd/conf.d/php.conf. For this file to be loaded, the statement Include conf.d/*.conf must be in httpd.conf as described in Section 10.2.1.3 Dynamic Shared Object (DSO) Support.

	Note
	Any PHP configuration directives used in Apache HTTP Server 1.3 are now fully compatible, when migrating to Apache HTTP Server 2.0 on Red Hat Enterprise Linux 4.

In PHP version 4.2.0 and later the default set of predefined variables which are available in the global scope has changed. Individual input and server variables are, by default, no longer placed directly into the global scope. This change may cause scripts to break. Revert to the old behavior by setting register_globals to On in the file /etc/php.ini.

For more on this topic, refer to the following URL for details concerning the global scope changes:

• https://www.php.net/release_4_1_0.php

10.2.4.9. The mod_authz_ldap Module

Red Hat Enterprise Linux ships with the mod_authz_ldap module for the Apache HTTP Server. This module uses the short form of the distinguished name for a subject and the issuer of the client SSL certificate to determine the distinguished name of the user within an LDAP directory. It is also capable of authorizing users based on attributes of that user's LDAP directory entry, determining access to assets based on the user and group privileges of the asset, and denying access for users with expired passwords. The mod_ssl module is required when using the mod_authz_ldap module.

	Important
	The mod_authz_ldap module does not authenticate a user to an LDAP directory using an encrypted password hash. This functionality is provided by the experimental mod_auth_ldap module. Refer to the mod_auth_ldap module documentation online at https://httpd.apache.org/docs-2.0/mod/mod_auth_ldap.html for details on the status of this module.

The /etc/httpd/conf.d/authz_ldap.conf file configures the mod_authz_ldap module.

Refer to /usr/share/doc/mod_authz_ldap-<version>/index.html (replacing <version> with the version number of the package) or https://authzldap.othello.ch/ for more information on configuring the mod_authz_ldap third party module.