In hosting situations, like ours, where IPv6 IP addresses are not natively supported by our servers, CloudFlare has a settings that allows you to convert the IPv6 IP address of the site visitor to an IPv4 address that CloudFlare uses so that the content can be retrieved by CloudFlare and then presented to the IPv6 only site visitor.
This action is accomplished by using the Pseudo IPv4 setting in your CloudFlare Settings tab.
The Pseudo IPv4 setting has three available options.
- Add header
- Overwrite headers
The first option is also the default setting for your CloudFlare account and will not influence the incoming traffic to the CloudFlare system. This means that if a site visitor that can only connect to the internet using IPv6, the CloudFlare system will not apply the appropriate headers to the HTTP requests.
The second option, “Add Header” allows the CloudFlare service to enter an HTTP header that will allow the visitor to “use” an IPv4 address to connect with.
This setting will apply the following header to the request:
The third option, “Overwrite header” will apply a different header to the HTTP request that has some additional functionality. The advantage of this option is that it will append a new header:
Which works to catalog the IP address of the actual connecting IP address for debugging.
This setting is available to all CloudFlare service customers, even those who use the free plan.