← Network / network
Pseudo IPv4
Cloudflare customers can use Pseudo IPv4 if their origin web server only understands IPv4 formatted IP addresses (meaning it would not support Cloudflare's default IPv6 compatibility).
Availability
| Free | Pro | Business | Enterprise | |
|---|---|---|---|---|
| Availability | Yes | Yes | Yes | Yes |
Background
Some older origin server analytics and fraud detection software expect IP addresses in an IPv4 format and do not support IPv6 addresses.
Pseudo IPv4 uses the Class E IPv4 address space ↗ to provide as many unique IPv4 addresses corresponding to IPv6 addresses as possible.
- Example Class E IPv4 address:
240.16.0.1 - Example IPv6 address:
2400:cb00:f00d:dead:beef:1111:2222:3333
Configure Pseudo IPv4
Cloudflare offers three options for configuring Pseudo IPv4:
- Off: Default value.
- Add Header: Cloudflare automatically adds the
Cf-Pseudo-IPv4header with a Class E IPv4 address hashed from the original IPv6 address. - Overwrite Headers:
If Pseudo IPv4 is set to
Overwrite Headers- Cloudflare overwrites the existingCf-Connecting-IPandX-Forwarded-Forheaders with a pseudo IPv4 address while preserving the real IPv6 address inCF-Connecting-IPv6header.
To configure Pseudo IPv4:
To change the Pseudo IPv4 setting in the dashboard:
-
In the Cloudflare dashboard, go to the Network page.
Go to Network ↗ -
For Pseudo IPv4, choose your desired setting.
To change Pseudo IPv4 with the API, send a PATCH request with pseudo_ipv4 as the setting name in the URI path, and the value parameter set to your desired value: "off", "add_header", or "overwrite_header".