WP Security Audit Log Support for Reverse Proxies & Web Application Firewalls

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WP Security Audit Log automatically retrieves the originating IP address of a user even when WordPress is running behind a reverse proxy, a web application firewall or load balancers.

WP Security Audit Log WordPress plugin can be configured to retrieve the originating IP Address of a WordPress user even if WordPress is running behind a reverse proxy, web application firewall or load balancers. This article explains how WP Security Audit Log can retrieve the originating WordPress user’s IP Address and not that of the proxy, firewall or load balancer.

WordPress and Reverse Proxy or Firewall Setup

In a typical setup, the reverse proxy or web application firewall is installed in front of the WordPress server. Therefore the user never communicates directly with WordPress. The user communicates with the reverse proxy and the proxy communications with WordPress, as seen in the below screenshot.

Typical WordPress and Reverse Proxy Setup Diagram

Hence in such a setup the default installation of WP Security Audit Log sees all the requests originating from the reverse proxy, which is 192.168.2.15.  In such case all WordPress security alerts will have 192.168.2.15 as originating IP address. To record the originating WordPress user IP address enable the option in the Reverse Proxy / Firewall Options as explained below.

Recording the Originating WordPress User IP Address in the WordPress Security Audit Log

WP Security Audit Log plugin has two options related to reverse proxy, firewall or load balancers WordPress setups, as seen in the below screenshot.

WP Security Audit Log Reverse Proxy and WAF Settings

WordPress Running Behind Firewall or Proxy Plugin Setting

When the first option WordPress running behind firewall or proxy is enabled, the plugin will retrieve the users’ IP address from any of the below headers, thus reporting the IP address of the user and not that of the firewall or proxy:

  • HTTP_CLIENT_IP
  • HTTP_X_FORWARDED_FOR
  • HTTP_X_FORWARDED
  • HTTP_X_CLUSTER_CLIENT_IP
  • HTTP_FORWARDED_FOR
  • HTTP_FORWARDED
  • REMOTE_ADDR

All of these headers are used by proxy servers, firewalls and load balancers to identify the originating IP address of a client connecting to a web server through a proxy, web application firewall or load balancer. The below screenshot shows the headers of connection being forwarded via a reverse proxy:

HTTP Headers of an HTTP Request originating from a Reverse Proxy

In some cases the connection between a WordPress user and a WordPress website can be routed through several network hops and such header can contain multiple IP addresses. WP Security Audit Log always reports the first IP address from the left as the originating one, as instructed in the RFC standards. Though it still stores all IP addresses in the headers as explained in the section below Retrieving All IP Addresses Reported in HTTP Headers.

Filter Internal IP Addresses Plugin Setting

By enabling the option Filter Internal IP Addresses, WP Security Audit Log plugin will not report the end user IP address should it be an internal IP address. This option has been implemented because in some cases there is the possibility that an internal IP is reported in the HTTP headers rather than a public IP address.

Retrieving All IP Addresses Reported in HTTP Headers

WP Security Audit Log plugin records all the IP addresses specified in any of the HTTP headers mentioned above but only displays the first one from the left since that should be the WordPress user originating IP address as per the RFCs. Though there might be cases where some servers do not follow the RFC and change the order of the IP addresses in these HTTP headers. In such situation, should you wish to see all the IP addresses reported in the HTTP headers follow the below procedure:

  1. Enable the option Data Inspector from the Developer Options in the plugin’s settings
  2. Click on the more details icon () of that alert for which you would like to see all the data
  3.  Expand the Other IPs node to see all other IP addresses specified in the header as shown in the screenshot below.

WordPress Security Alert Data Inspector

From the above screenshot you can notice that the reverse proxy used the HTTP_X_FORWARDED_FOR header and the WordPress user’s originating IP address is 192.168.2.124. You can also notice the proxy’s IP address 192.168.2.15 in the REMOTE_ADDR header.