Router/Firewall/Clients

Setup

vi /etc/network/interfaces
1) To insert text, press “I”.
2) To stop inserting text, press ESCAPE.
3) To save, type “:w” and press ENTER.
4) To quit, type “:q” and press ENTER.
5) To save and quit type “:wq”.
6) To enter append mode, press “A”.
7) To exit without saving type “:q!”.
nano vi /etc/network/interfaces 

Set a static IP on Kali Linux to properly setup on the network. Use vi /etc/network/interfaces on Kali Linux to look
like the following:

E.g. Kali

auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.100.201
netmask 255.255.255.0
network 192.168.100.0

Now restart the networking to apply the settings just configured. On Kali Linux, execute: /etc/init.d/networking restart

Now verify the status, execute: /etc/init.d/networking status
Restart the guest machine and verify ip by ifconfig

Repeat with different address

E.g. Metasploitable 

auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.100.202
netmask 255.255.255.0
network 192.168.100.0