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.

### 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

### Bugfix checklist

- httpd changelog
- Known issues
- Report a bug

### See also

- `Require`
- `mod_authz_host`
- `mod_authz_core`

## 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.

## 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 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

- `Allow`
- `Require`