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Apache HTTP Server Version 2.4
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Apache Module mod_access_compat
| 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.
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
Bugfix checklist
See also
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.
Allow from 10.1.2.3 Allow from 192.168.1.104 192.168.1.205
An IP address of a host allowed access
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.
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.
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.
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.
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.
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 we wanted to let people on your network have unrestricted access to a portion of the website, but require that people outside of your network provide a password, we 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