With industry security standards and audit requirements, you may need high-level security tuning for a public Drupal website. There are several methods you can use to do tuning, including adding a module to your website or configuring IP restriction in Drupal itself. You may also want to block particular IP addresses due to attacks or other problems.

IP restriction in Drupal (Recommended)

IP restriction in Drupal is an important addition to protect websites from unwanted visitors. Whether these websites are development testbeds that should be kept from the general web, or private intranets of companies hosted in the cloud, it’s important to know your website is safe from prying eyes.

Acquia hosting subscribers don’t have access to Apache’s VirtualHosts, and can’t add standard Apache protections. There is no all-encompassing module or other easy method to both protect administrative file paths and restrict access to only allowlisted IP addresses on Cloud Platform.

It’s possible to restrict content service to users accessing the website from an allowed IP, users with the correct HTTP authentication, or both. Use the method based on your website’s installed version of Drupal:

Redirecting users outside an IP address range with .htaccess

In a non-Acquia hosting environment, you can use the %{REMOTE_ADDR} variable in the .htaccess file to redirect users to Google if they’re not in the 123.456.* IP address range. This does not work on Cloud Platform because of its load balancing structure.

To carry out the redirect on Cloud Platform, use the %{ENV:AH_Client_IP} variable:

RewriteCond %{ENV:AH_Client_IP} !^123\.456\..*
RewriteRule ^http://www.google.com [R=307,L]

For more information about blocking with .htaccess and rewrites, see Blocking access using rewrites.

Blocking by IP with mod_rewrite in .htaccess

Cloud Platform uses Varnish® and load balancers, causing typical access controls to not work as expected. This method is like the one detailed in and .

Restricting website access

RewriteCond %{ENV:AH_Client_IP} !^123\.456\..*
RewriteRule ^http://www.google.com [R=307,L]

Alternate use cases

If you do not need the flexibility the Drupal IP restriction offers, there are some tasks you can use requiring less code, and if you have a small restriction, may be easier to upkeep.

• Redirecting users outside an IP address range with .htaccess
• Blocking by IP with mod_rewrite in .htaccess
• Using XFF headers to block by IP address

You must ensure that these rules are in the section determining that the Apache mod_rewrite module is enabled. If these rules are not present, the redirects fail.

To block a single IP, the following example sets an environment variable on the specific IP address 192.168.15.20, using mod_setenvif. You must add the following code to the top of the .htaccess file:

To block several IPs, the following example blocks addresses from the group 104.128.*.* and the IP address 192.168.10.10. You can specifically deny access to these two subnets and allow access to all other IPs. You must add the following code to the top of the .htaccess file:

All IPs in the 104.128 subnet and the IP address 192.168.10.10 get a DENY environment variable. The rewrite rules check for allowed, and then deny everyone with a DENY variable.

To restrict access and allow only certain IP addresses to reach a website, you can add the following code to the top of the .htaccess file:

The most recent preceding code is the opposite of the first example, by using the ALLOW environment variable to give only certain groups access to the website, instead of denying those groups.

Using XFF headers to block by IP address

If blocking by IP in .htaccess using AH_Client_IP doesn’t work, you can use the X-Forwarded-For header. The following example includes this header in the blocking rules in .htaccess:

The rule based on the X-Forwarded-For (XFF) does not anchor the pattern at the beginning (^) or end ($). If the target string appears anywhere in the value of the XFF header, the request is blocked. However, you must exercise caution when using this approach not to match a pattern more broadly than intended. For example, a pattern like 12.23 matches the IP: 22.112.234.55. For optimum results, Acquia recommends that your patterns are as specific as possible.

Alternate use cases

If you do not need the flexibility the Drupal IP restriction offers, there are some tasks you can use requiring less code, and if you have a small restriction, may be easier to upkeep.

• Redirecting users outside an IP address range with .htaccess
• Blocking by IP with mod_rewrite in .htaccess
• Using XFF headers to block by IP address

You must ensure that these rules are in the section determining that the Apache mod_rewrite module is enabled. If these rules are not present, the redirects fail.

To block a single IP, the following example sets an environment variable on the specific IP address 192.168.15.20, using mod_setenvif. You must add the following code to the top of the .htaccess file:

To block several IPs, the following example blocks addresses from the group 104.128.*.* and the IP address 192.168.10.10. You can specifically deny access to these two subnets and allow access to all other IPs. You must add the following code to the top of the .htaccess file:

All IPs in the 104.128 subnet and the IP address 192.168.10.10 get a DENY environment variable. The rewrite rules check for allowed, and then deny everyone with a DENY variable.

To restrict access and allow only certain IP addresses to reach a website, you can add the following code to the top of the .htaccess file:

The most recent preceding code is the opposite of the first example, by using the ALLOW environment variable to give only certain groups access to the website, instead of denying those groups.

Using XFF headers to block by IP address

If blocking by IP in .htaccess using AH_Client_IP doesn’t work, you can use the X-Forwarded-For header. The following example includes this header in the blocking rules in .htaccess:

The rule based on the X-Forwarded-For (XFF) does not anchor the pattern at the beginning (^) or end ($). If the target string appears anywhere in the value of the XFF header, the request is blocked. However, you must exercise caution when using this approach not to match a pattern more broadly than intended. For example, a pattern like 12.23 matches the IP: 22.112.234.55. For optimum results, Acquia recommends that your patterns are as specific as possible.