---
title: Pseudo IPv4
description: Map IPv6 addresses to IPv4 for legacy origin servers.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/network/llms.txt  
> Use this file to discover all available pages before exploring further.

[Skip to content](#%5Ftop) 

# 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](https://developers.cloudflare.com/network/ipv6-compatibility/)).

Note

To allow IPv6-only clients to connect to IPv4-only origin web servers, keep [IPv6 compatibility](https://developers.cloudflare.com/network/ipv6-compatibility/) enabled and configure Pseudo IPv4.

## 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 ↗](https://tools.ietf.org/html/rfc1112#section-4) 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`

Note

Class E IPv4 addresses are designated as experimental and are not used for production Internet traffic.

## Configure Pseudo IPv4

Cloudflare offers three options for configuring **Pseudo IPv4**:

* **Off**: Default value.
* **Add Header**: Cloudflare automatically adds the `Cf-Pseudo-IPv4` header 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 existing `Cf-Connecting-IP` and `X-Forwarded-For` headers with a pseudo IPv4 address while preserving the real IPv6 address in `CF-Connecting-IPv6` header.

Note

When using _Overwrite Headers_, no software changes are necessary in your origin web server.

To configure **Pseudo IPv4**:

* [ Dashboard ](#tab-panel-7057)
* [ API ](#tab-panel-7058)

To change the **Pseudo IPv4** setting in the dashboard:

1. In the Cloudflare dashboard, go to the **Network** page.  
[ Go to **Network** ](https://dash.cloudflare.com/?to=/:account/:zone/network)
2. For **Pseudo IPv4**, choose your desired setting.

To change **Pseudo IPv4** with the API, send a [PATCH](https://developers.cloudflare.com/api/resources/zones/subresources/settings/methods/edit/) 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"`.

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/network/","name":"Network"}},{"@type":"ListItem","position":3,"item":{"@id":"/network/pseudo-ipv4/","name":"Pseudo IPv4"}}]}
```