knockd

Installiere knockd:
```
sudo pacman -S knockd
```

Bearbeite die Konfigurationsdatei /etc/knockd.conf.

[options]
    logfile = /var/log/knockd.log

[openSSH]
    sequence    = 7000,8000,9000
    seq_timeout = 5
    command     = /usr/sbin/iptables -A INPUT -s %IP% -p tcp --dport 2222 -j ACCEPT
    tcpflags    = syn

[closeSSH]
    sequence    = 9000,8000,7000
    seq_timeout = 5
    command     = /usr/sbin/iptables -D INPUT -s %IP% -p tcp --dport 2222 -j ACCEPT
    tcpflags    = syn

Starte knockd:
```
sudo systemctl enable --now knockd
```

Port-Knocking