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# Portsentry

O intuito do Portsentry é abrir diversas portas falsas no host e bloquear tentativas de intrusão.<br>

### Instalando

```bash
apt install portsentry
```

### Configurando

Em `/etc/portsentry/portsentry.conf`, habilite as regras de firewall de acordo com a sua utilização em `KILL_ROUTE` (por exemplo, podemos utilizar o `iptables`). Defina a opção `BLOCK_TCP` e `BLOCK_UDP` definidas como `1` para bloquear o host atacante. Nas flags `TCP_PORTS` e `UDP_PORTS`, utilize quantas portas quiser, desde que não seja portas que já esteja utilizando em outros serviços.

{% hint style="info" %}
**OBS**.: Sempre que alterar esse arquivo de configuração, reinicie o serviço utilizando o comando: **`service portsentry restart`**
{% endhint %}

Quando realizamos um scan com o nmap contra a máquina que possui o portsentry e utilizamos a flag `-sV`, iremos receber um `tcpwrapper` no nome do serviço, indicando a conexão foi estabelecida mas depois o host encerrou/bloqueou a conexão.

#### Bloquando Stealth Scan

Por padrão o portsentry não bloqueia scan do Stealth Scan do nmap (parâmetro `-sS`), então utilize o comando abaixo para realizar esse bloqueio:

```bash
/usr/sbin/portsentry -stcp
```


---

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