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Apache > HTTP Server > Documentation > Version 2.4 > Modules

Apache Module mod_access_compat

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Description:Group authorizations based on host (name or IP address)
Status:Extension
Module Identifier:access_compat_module
Source File:mod_access_compat.c
Compatibility:Available in Apache HTTP Server 2.3 as a compatibility module with previous versions of Apache httpd 2.x. The directives provided by this module have been deprecated by the new authz refactoring. Please see mod_authz_host

Summary

The directives provided by mod_access_compat are used in <Directory>, <Files>, and <Location> sections as well as .htaccess files to control access to particular parts of the server. Access can be controlled based on the client hostname, IP address, or other characteristics of the client request, as captured in environment variables. The Allow and Deny directives are used to specify which clients are or are not allowed access to the server, while the Order directive sets the default access state, and configures how the Allow and Deny directives interact with each other.

Both host-based access restrictions and password-based authentication may be implemented simultaneously. In that case, the Satisfy directive is used to determine how the two sets of restrictions interact.

Note

The directives provided by mod_access_compat have been deprecated by mod_authz_host. Mixing old directives like Order, Allow or Deny with new ones like Require is technically possible but discouraged. This module was created to support configurations containing only old directives to facilitate the 2.4 upgrade. Please check the upgrading guide for more information.

In general, access restriction directives apply to all access methods (GET, PUT, POST, etc). This is the desired behavior in most cases. However, it is possible to restrict some methods, while leaving other methods unrestricted, by enclosing the directives in a <Limit> section.

Merging of configuration sections

When any directive provided by this module is used in a new configuration section, no directives provided by this module are inherited from previous configuration sections.

Directives

See also

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Allow Directive

Description:Controls which hosts can access an area of the server
Syntax: Allow from all|host|env=[!]env-variable [host|env=[!]env-variable] ...
Context:directory, .htaccess
Override:Limit
Status:Extension
Module:mod_access_compat

The Allow directive affects which hosts can access an area of the server. Access can be controlled by hostname, IP address, IP address range, or by other characteristics of the client request captured in environment variables.

The first argument to this directive is always from. The subsequent arguments can take three different forms. If Allow from all is specified, then all hosts are allowed access, subject to the configuration of the Deny and Order directives as discussed below. To allow only particular hosts or groups of hosts to access the server, the host can be specified in any of the following formats:

A (partial) domain-name
Allow from example.org
Allow from .net example.edu

Hosts whose names match, or end in, this string are allowed access. Only complete components are matched, so the above example will match foo.example.org but it will not match fooexample.org. This configuration will cause Apache httpd to perform a double DNS lookup on the client IP address, regardless of the setting of the HostnameLookups directive. It will do a reverse DNS lookup on the IP address to find the associated hostname, and then do a forward lookup on the hostname to assure that it matches the original IP address. Only if the forward and reverse DNS are consistent and the hostname matches will access be allowed.

A full IP address
Allow from 10.1.2.3
Allow from 192.168.1.104 192.168.1.205

An IP address of a host allowed access

A partial IP address
Allow from 10.1
Allow from 10 172.20 192.168.2

The first 1 to 3 bytes of an IP address, for subnet restriction.

A network/netmask pair
Allow from 10.1.0.0/255.255.0.0

A network a.b.c.d, and a netmask w.x.y.z. For more fine-grained subnet restriction.

A network/nnn CIDR specification
Allow from 10.1.0.0/16

Similar to the previous case, except the netmask consists of nnn high-order 1 bits.

Note that the last three examples above match exactly the same set of hosts.

IPv6 addresses and IPv6 subnets can be specified as shown below:

Allow from 2001:db8::a00:20ff:fea7:ccea
Allow from 2001:db8::a00:20ff:fea7:ccea/10

The third format of the arguments to the Allow directive allows access to the server to be controlled based on the existence of an environment variable. When Allow from env=env-variable is specified, then the request is allowed access if the environment variable env-variable exists. When Allow from env=!env-variable is specified, then the request is allowed access if the environment variable env-variable doesn't exist. The server provides the ability to set environment variables in a flexible way based on characteristics of the client request using the directives provided by mod_setenvif. Therefore, this directive can be used to allow access based on such factors as the clients User-Agent (browser type), Referer, or other HTTP request header fields.

SetEnvIf User-Agent ^KnockKnock/2\.0 let_me_in
<Directory "/docroot">
    Order Deny,Allow
    Deny from all
    Allow from env=let_me_in
</Directory>

In this case, browsers with a user-agent string beginning with KnockKnock/2.0 will be allowed access, and all others will be denied.

Merging of configuration sections

When any directive provided by this module is used in a new configuration section, no directives provided by this module are inherited from previous configuration sections.

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Deny Directive

Description:Controls which hosts are denied access to the server
Syntax: Deny from all|host|env=[!]env-variable [host|env=[!]env-variable] ...
Context:directory, .htaccess
Override:Limit
Status:Extension
Module:mod_access_compat

This directive allows access to the server to be restricted based on hostname, IP address, or environment variables. The arguments for the Deny directive are identical to the arguments for the Allow directive.

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Order Directive

Description:Controls the default access state and the order in which Allow and Deny are evaluated.
Syntax: Order ordering
Default:Order Deny,Allow
Context:directory, .htaccess
Override:Limit
Status:Extension
Module:mod_access_compat

The Order directive, along with the Allow and Deny directives, controls a three-pass access control system. The first pass processes either all Allow or all Deny directives, as specified by the Order directive. The second pass parses the rest of the directives (Deny or Allow). The third pass applies to all requests which do not match either of the first two.

Note that all Allow and Deny directives are processed, unlike a typical firewall, where only the first match is used. The last match is effective (also unlike a typical firewall). Additionally, the order in which lines appear in the configuration files is not significant -- all Allow lines are processed as one group, all Deny lines are considered as another, and the default state is considered by itself.

Ordering is one of:

Allow,Deny
First, all Allow directives are evaluated; at least one must match, or the request is rejected. Next, all Deny directives are evaluated. If any matches, the request is rejected. Last, any requests which do not match an Allow or a Deny directive are denied by default.
Deny,Allow
First, all Deny directives are evaluated; if any match, the request is denied unless it also matches an Allow directive. Any requests which do not match any Allow or Deny directives are permitted.
Mutual-failure
This order has the same effect as Order Allow,Deny and is deprecated in its favor.

Keywords may only be separated by a comma; no whitespace is allowed between them.

Match Allow,Deny result Deny,Allow result
Match Allow only Request allowed Request allowed
Match Deny only Request denied Request denied
No match Default to second directive: Denied Default to second directive: Allowed
Match both Allow & Deny Final match controls: Denied Final match controls: Allowed

In the following example, all hosts in the example.org domain are allowed access; all other hosts are denied access.

Order Deny,Allow
Deny from all
Allow from example.org

In the next example, all hosts in the example.org domain are allowed access, except for the hosts which are in the foo.example.org subdomain, who are denied access. All hosts not in the example.org domain are denied access because the default state is to Deny access to the server.

Order Allow,Deny
Allow from example.org
Deny from foo.example.org

On the other hand, if the Order in the last example is changed to Deny,Allow, all hosts will be allowed access. This happens because, regardless of the actual ordering of the directives in the configuration file, the Allow from example.org will be evaluated last and will override the Deny from foo.example.org. All hosts not in the example.org domain will also be allowed access because the default state is Allow.

The presence of an Order directive can affect access to a part of the server even in the absence of accompanying Allow and Deny directives because of its effect on the default access state. For example,

<Directory "/www">
    Order Allow,Deny
</Directory>

will Deny all access to the /www directory because the default access state is set to Deny.

The Order directive controls the order of access directive processing only within each phase of the server's configuration processing. This implies, for example, that an Allow or Deny directive occurring in a <Location> section will always be evaluated after an Allow or Deny directive occurring in a <Directory> section or .htaccess file, regardless of the setting of the Order directive. For details on the merging of configuration sections, see the documentation on How Directory, Location and Files sections work.

Merging of configuration sections

When any directive provided by this module is used in a new configuration section, no directives provided by this module are inherited from previous configuration sections.

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Satisfy Directive

Description:Interaction between host-level access control and user authentication
Syntax:Satisfy Any|All
Default:Satisfy All
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_access_compat
Compatibility:Influenced by <Limit> and <LimitExcept> in version 2.0.51 and later

Access policy if both Allow and Require used. The parameter can be either All or Any. This directive is only useful if access to a particular area is being restricted by both username/password and client host address. In this case the default behavior (All) is to require that the client passes the address access restriction and enters a valid username and password. With the Any option the client will be granted access if they either pass the host restriction or enter a valid username and password. This can be used to password restrict an area, but to let clients from particular addresses in without prompting for a password.

For example, if you wanted to let people on your network have unrestricted access to a portion of your website, but require that people outside of your network provide a password, you could use a configuration similar to the following:

Require valid-user
Allow from 192.168.1
Satisfy Any

Another frequent use of the Satisfy directive is to relax access restrictions for a subdirectory:

<Directory "/var/www/private">
    Require valid-user
</Directory>

<Directory "/var/www/private/public">
    Allow from all
    Satisfy Any
</Directory>

In the above example, authentication will be required for the /var/www/private directory, but will not be required for the /var/www/private/public directory.

Since version 2.0.51 Satisfy directives can be restricted to particular methods by <Limit> and <LimitExcept> sections.

Merging of configuration sections

When any directive provided by this module is used in a new configuration section, no directives provided by this module are inherited from previous configuration sections.

See also

Available Languages:  en  |  fr  |  ja 

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Comments

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