---
title: Specify NAT method
sidebar_position: 4
description: Configuring NAT with Besu
---

> For AI agents: a documentation index is available at [/llms.txt](/llms.txt). Append `.md` to any documentation URL to get the markdown source.


# Specify the NAT method

Use the [`--nat-method`](../../reference/cli/options.md#nat-method) option to specify the NAT method. Options are: [`UPNP`](#upnp), [`DOCKER`](#docker), [`AUTO`](#auto), and [`NONE`](#none).

The [enode](../../concepts/node-keys.md#enode-url) advertised to other nodes during discovery is the external IP address and port. The [`admin_nodeInfo`](../../reference/api/index.md#admin_nodeinfo) JSON-RPC API method returns the external address and port for the `enode` and `listenAddr` properties.

While Besu is running, the following are not supported:

- IP address changes
- Changing NAT methods. To change the NAT method, restart the node with the [`--nat-method`](../../reference/cli/options.md#nat-method) option set.

## Auto

`AUTO` detects if Besu is running inside a Docker container.
If Besu is running in a Docker container, `AUTO` sets to [`DOCKER`](#docker).
If Besu is not running in a Docker container, `AUTO` sets to [`NONE`](#none).

`AUTO` is the default NAT method.

:::tip

If automatic detection fails, set the IP and ports in [`NONE`](#none) mode.

:::

## UPnP

Specify `UPNP` to quickly allow inbound peer connections without manual router configuration. Use UPnP in home or small office environments where a wireless router or modem provides NAT isolation.

UPnP automatically detects if a node is running in a UPnP environment and provides port forwarding. UPnP might introduce delays during node startup, especially on networks without a UPnP gateway device.

Use `UPNPP2PONLY` if you wish to enable UPnP only for p2p traffic.

:::tip

UPnP support is often disabled by default in networking firmware. If disabled by default, you must explicitly enable UPnP support.

:::

:::info

When the NAT method is set to `UPNP`, the advertised port is the same as the [listening port](../../reference/cli/options.md#p2p-port).

:::

## Docker

Specify `DOCKER` to explicitly specify Besu is running inside a Docker container. If you specify `DOCKER`, you advertise the host IP address not the container IP address.

The host IP address is the advertised host specified in the [`docker run` command](https://docs.docker.com/engine/reference/commandline/run/#add-entries-to-container-hosts-file---add-host). If not specified in the `docker run` command, the advertised host defaults to the values for [`--p2p-host`](../../reference/cli/options.md#p2p-host) and [`--p2p-port`](../../reference/cli/options.md#p2p-port).

## None

Specify `NONE` to explicitly configure the external IP address and ports advertised using:

- [`--p2p-host`](../../reference/cli/options.md#p2p-host) and [`--p2p-port`](../../reference/cli/options.md#p2p-port) for the P2P service.
- [`--rpc-http-host`](../../reference/cli/options.md#rpc-http-host) and [`--rpc-http-port`](../../reference/cli/options.md#rpc-http-port) for the JSON-RPC HTTP service.

The P2P and JSON-RPC HTTP hosts and ports are advertised in the [`net_services`](../../reference/api/index.md#net_services) method.

:::tip

When the NAT method is set to `NONE`, the advertised port is the same as the [listening port](../../reference/cli/options.md#p2p-port).

:::