update-alternatives --set iptables /usr/sbin/iptables-legacy

cat /etc/iptables 
# sample configuration for iptables service
# you can edit this manually or use system-config-firewall
# please do not ask us to add additional ports/services to this default configuration
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT

#NFS
-A INPUT -p tcp -m state --state NEW -m tcp --dport 2049 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 2049 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 111 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 111 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 32803 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 32769 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 892 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 892 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 662 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 662 -j ACCEPT


#qbittorrent UI
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8080 -j ACCEPT
#qbittorrent direct conn
#-A INPUT -p tcp -m state --state NEW -m tcp --dport 4433 -j ACCEPT
#-A INPUT -p udp -m state --state NEW -m udp --dport 4433 -j ACCEPT
#-A INPUT -p tcp -m state --state NEW -m tcp --dport 6881 -j ACCEPT
#-A INPUT -p udp -m state --state NEW -m udp --dport 6881 -j ACCEPT

#X11VNC
-A INPUT -p tcp -m state --state NEW -m tcp --dport 5900 -j ACCEPT

-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

iptables-restore < /etc/iptables
iptables -L

zajisteni persistence nastaveni

iptables-save > /etc/iptables.up.rules

cat /etc/network/if-pre-up.d/iptables
 #!/bin/sh
 /sbin/iptables-restore < /etc/iptables.up.rules

chmod +x /etc/network/if-pre-up.d/iptables