GATEWAY

$~$

VIRTUAL NETWORK

Hyper-V manager: Create new Virtual Private Switch

$~$

II. Gateway machine

Configure network interfaces

file /etc/network/interfaces

# This file describes the network interfaces available 
# on your system and how to activate them. For more 
# information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface

auto lo
iface lo inet loopback

# The primary network interface

allow-hotplug eth0
iface eth0 inet dhcp

# The secondary face

allow-hotplug eth1
    iface eth1 inet static
    address 10.0.10.1
    netmask 255.255.255.0
    dns-nameservers 10.0.10.1

Configure DHCP, DNS:

Configure iptables (masquearde)

# apt install -y iptables

create script and give executable privileges to it:

file /etc/network/if-up.d/001masquerade

#!/bin/sh

# Reload the iptables rules and activate forwarding
# delete all existing rules.

iptables -Z # zero counters
iptables -F # flush (delete) rules
iptables -t mangle -F
iptables -X # delete all extra chains

# If you want to clear the chains, then clear the chains:

iptables --policy INPUT ACCEPT;
iptables --policy OUTPUT ACCEPT;
iptables --policy FORWARD ACCEPT;

# Masquerade.

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

# Enable routing.

echo 1 > /proc/sys/net/ipv4/ip\_forward

exit 0

Create test page on faked address: http://ufo.mars

# apt install -y apache2

file: /var/www/html/index.html

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" 
      content="text/html; charset=UTF-8" >
<title>Welcome to Mars</title>
</head>
<body>
<span style="color:red"><h1>WELCOME TO MARS</h1></span>
<img src="mars.jpg">
</body>
</html>

SystemRescueCD machine

systemctl status NetworkManager --no-pager

On Ubuntu 20.04

open http://ufo.mars)

You have to see this:

$~$

SHOOTING TROUBLE

No SSH connection with "private switch" nodes.

Allow packet forwarding on host (REGEDIT, reboot required):

Computer\
 HKEY_LOCAL_MACHINE\
   SYSTEM\
     CurrentControlSet\
       Services\
         Tcpip\
           Parameters
IPEnableRouter   REG_DWORD   1

Make sure your ssh daemon is configured, up and running Networking

old style:

# ifconfig enp0s3 10.0.10.100 up
# route add default gw 10.0.10.1

new style:

# ip link set dev eth0 up mtu 1500
# ip addr add dev eth0 10.0.0.2/24 broadcast 10.0.0.255
# ip route add 10.0.0.2/24 via 10.0.0.1

https://www.cyberciti.biz/faq/ip-route-add-network-command-for-linux-explained/

Permanent DNS

old style:

# echo nameserver 192.168.253.250 > /etc/resolv.conf
# echo nameserver 192.168.253.249 >> /etc/resolv.conf

new style:

#!/bin/bash

apt install -y resolvconf
systemctl status resolvconf.service
echo nameserver 192.168.253.250 > \
    /etc/resolvconf/resolv.conf.d/head
echo nameserver 192.168.253.249 >> \
    /etc/resolvconf/resolv.conf.d/head
systemctl restart resolvconf.service