allow

Syntax: allow from host host ...
Context: directory, .htaccess
Override: Limit
Status: Base
Module: mod_access

The allow directive affects which hosts can access a given directory. Host is one of the following:

all: All hosts are allowed access
A (partial) domain-name: Hosts whose names match, or end in, this string are allowed access.
A full IP address: An IP address of a host allowed access
A partial IP address: The first 1 to 3 bytes of an IP address, for subnet restriction.
A network/netmask pair (Apache 1.3 and later): A network a.b.c.d, and a netmask w.x.y.z. For more fine-grained subnet restriction. (i.e., 10.1.0.0/255.255.0.0)
A network/nnn CIDR specification (Apache 1.3 and later): Similar to the previous case, except the netmask consists of nnn high-order 1 bits. (i.e., 10.1.0.0/16 is the same as 10.1.0.0/255.255.0.0)

Example:

allow from .ncsa.uiuc.edu

All hosts in the specified domain are allowed access.

Note that this compares whole components; bar.edu would not match foobar.edu.

Syntax: allow from env=variablename
Context: directory, .htaccess
Override: Limit
Status: Base
Module: mod_access
Compatibility: Apache 1.2 and above

The allow from env directive controls access to a directory by the existence (or non-existence) of an environment variable.

Example:

BrowserMatch ^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 the user-agent string KnockKnock/2.0 will be allowed access, and all others will be denied.