Building a Linux Gateway using Ubuntu Server 18.04

This post documents how to build a Linux gateway using Ubuntu Server 18.04. The gateway connects an internal network to an external network - basically, performing Network Address Translation (NAT) for hosts on the internal network. It is exceptionally similar to what your ISP supplied home router does. To achieve this, an Ubuntu Linux server is configured as a DHCP server and also to provide NAT using iptables.

Contents

• Introduction
• Configure Network Interface Cards
• Install DHCP server
• Configure Network Address Translation
• Configuring Internal Hosts: Linux
• Configuring Internal Hosts: Windows
• Check Network Connectivity

Introduction

This tutorial is written when building a blueprint for VMWare vRealize, but the instructions lend to any virtualization, or normal, system. The gateway connects to an external network named vlan25_Profile which provides Internet access, and a second network, InternalNetwork, which is an isolated network. While host1 only connects to the InternalNetwork. The vRealize blueprint for the network is displayed below.