net-nat

Life behind a NAT (Network Address Translator).

The main purpose of this package is to allow a server behind a NAT to accept connections from the public internet.

It uses the following protocols to create a public IP address

• RFC 6887 - NAT Port Control Protocol
• RFC 6886 - NAT Port Mapping Protocol

It supports the following runtimes

• .NET Framework 4.5
• .NET Standard 2.0

More information is on the Documentation web site.

Library

Getting started

Published releases are available on NuGet. To install, run the following command in the Package Manager Console.

PM> Install-Package Makaretu.Nat

Or using dotnet

> dotnet add package Makaretu.Nat

Usage

Find the NAT(s) and create a public address, LeasedEndPoint.

using Makaretu.Nat;
using System.Net.Sockets;

var endpoints = new List<LeasedEndpoint>();
foreach (var nat in NatDiscovery.GetNats())
{ 
    var lease = await nat.CreatePublicEndpointAsync(ProtocolType.Tcp, 8080);
    var endpoint = new LeasedEndpoint(lease);
    endpoints.Add(endpoint);
    Console.WriteLine($"Public address {endpoint}");
}

// Do your work.

foreach (var endpoint in endpoints)
{
    endpoint.Dispose();
}

Tool

Install

The natcheck tool is available on Nuget and is installed with dotnet.

> dotnet tool install --global natcheck

Usage

natcheck is a tool to examine the environment and display the network settings.

natcheck

Check your NAT(s)

Unicast addresses
  169.254.253.248 is public False
  192.168.178.21 is public False
  fe80::8891:f4b8:3f8:fdf8%10 is public False
  2406:e001:xxxx:f601:7573:b0a8:46b0:xxxx is public True
  2406:e001:xxxx:f601:49f5:3a68:e240:xxxx is public True
  fe80::7573:xxxx:46b0:xxxx%11 is public False

Gateways
  fe80::3a10:d5ff:fe09:1c0e%11
    supports NAT-PCP False
    supports NAT-PMP False
  192.168.178.1
    supports NAT-PCP True
    supports NAT-PMP False

Nats
  192.168.178.1:5351 fritz.box
  Public endpoint 165.84.19.45:8080