Firewall richtig konfiguriert?

HeyHo,

ich beschäftige mich gerade mit der Absicherung meines Debian Servers.
Ich habe dazu ein Bash-Script geschrieben. Was haltet ihr davon? :) Anregungen und Verbesserungen erwünscht.

Code:

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#!/bin/bash

echo "Initializing Firewall ..."

# Load modules
modprobe ip_conntrack_ftp

# Clear all other rules
iptables -F
iptables -X
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

# Creation of my own chains
iptables -N mydrop

# Configuring our own chains
iptables -A mydrop -j LOG --log-prefix "FW-DROP: "
iptables -A mydrop -j DROP

# Loopback communication
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

# Statefull Inspection
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m state --state INVALID -j mydrop
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# SSH
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT

# ICMP Ping
iptables -A INPUT -p icmp -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p icmp -m state --state NEW -j ACCEPT

# DNS
#iptables -A INPUT -p udp --dport 53 -m state --state NEW -j ACCEPT
#iptables -A INPUT -p tcp --dport 53 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p udp --dport 53 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p tcp --dport 53 -m state --state NEW -j ACCEPT

# WWW
#iptables -A INPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT
#iptables -A INPUT -p tcp --dport 443 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p tcp --dport 443 -m state --state NEW -j ACCEPT

# Mail
#iptables -A INPUT -p tcp --dport 25 -m state --state NEW -j ACCEPT
#iptables -A OUTPUT -p tcp --dport 25 -m state --state NEW -j ACCEPT
#iptables -A INPUT -p tcp --dport 110 -m state --state NEW -j ACCEPT
#iptables -A INPUT -p tcp --dport 143 -m state --state NEW -j ACCEPT

# FTP
iptables -A INPUT -p tcp --dport 21 -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p tcp --dport 21 -m state --state NEW -j ACCEPT

# DHCP
#iptacles -A INPUT -p udp --dport 67 -m state --state NEW -j ACCEPT

#Teamspeak 3 Server
iptables -A INPUT -p udp --dport 9987 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 30033 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 10011 -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p udp --dport 2010 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp --dport 41144 -m state --state NEW -j ACCEPT
iptables -A OUTPUT -p tcp --dport 2008 -m state --state NEW -j ACCEPT


echo "Firewall is configured and active!"

iptables -A INPUT -j LOG --log-prefix "FW-NOT-MATCHED:"
iptables -A INPUT -j DROP
iptables -A OUTPUT -j LOG --log-prefix "FW-NOT-MATCHED:"
iptables -A OUTPUT -j DROP

exit 0

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