×
The terminal on the right side controls your PC (192.168.0.10). The panel on the left controls an "intruder" machine (10.0.0.10 by default).
On your PC, you can run iptables commands to limit incoming/outgoing connections. On the intruder machine, you can attempt to make connections to your PC. Based on your firewall rules, these connections may succeed (✔) or fail (✕).
There is also a DNS server (1.1.1.1) and an HTTP Web server (1.1.1.10, example.com) that can be accessed from your PC via cURL
┌────┐
┌──────┐ ┌──│ ┌────┐ ┌────────┐
│ Your ├────┐ ┌──│ Internet ├────┐ │ │
│ PC │ └────┤ |┘ └─────┤Intruder│
└──────┘ └──────┬──────┘ │ │
192.168.0.10 │ └────────┘
┌────┴────┐ 10.0.0.10
│ │ (default)
┌───┴───┐ ┌───┴───┐
│ DNS │ │ Web │
│ Server│ │ Server│
└───────┘ └───────┘
1.1.1.1 1.1.1.10
(example.com)