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

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# Pseudo IPv4

Last updated Aug 25, 2026|Copy as Markdown|[View as Markdown](https://66f4ea29.previews.developers.cloudflare.com/network/pseudo-ipv4/index.md)|[Agent setup](https://66f4ea29.previews.developers.cloudflare.com/agent-setup/)

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://66f4ea29.previews.developers.cloudflare.com/network/ipv6-compatibility/)).

Note

To allow IPv6-only clients to connect to IPv4-only origin web servers, keep [IPv6 compatibility](https://66f4ea29.previews.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**:

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://66f4ea29.previews.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"`.

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