#!/bin/bash
# ---------------------------------------------------------------------
# Linux-iptables-Firewallskript, Copyright (c) 2007 under the GPL
# Autogenerated by iptables Generator v1.22 (c) 2002-2006 by Harald Bertram
# Please visit http://harry.homelinux.org for new versions of
# the iptables Generator (c).
#
# If you have questions about the iptables Generator or about
# your Firewall-Skript feel free to take a look at out website or
# send me an E-Mail to webmaster@harry.homelinux.org.
#
# My special thanks are going to Lutz Heinrich (trinitywork at hotmail dot com)
# who made lots of Beta-Testing and gave me lots of well qualified
# Feedback that made me able to improve the iptables Generator.
# --------------------------------------------------------------------
#
#
#
# BEGIN INIT INFO
# Provides: IP-Paketfilter
# Required-Start: $network $local_fs
# Required-Stop: $local_fs
# Default-Start: 3 5
# Default-Stop: 0 1 2 4 6
# Short-Description: Harry's IP-Paketfilter
# Description: Harry's IP-Paketfilter provides reasonable
# IP-Security for Home-Computers and small networks
#
# END INIT INFO
#
case "$1" in
start)
echo "Starte IP-Paketfilter"
# iptables-Modul
modprobe ip_tables
# Connection-Tracking-Module
modprobe ip_conntrack
# Das Modul ip_conntrack_irc ist erst bei Kerneln >= 2.4.19 verfuegbar
modprobe ip_conntrack_irc
modprobe ip_conntrack_ftp
# Tabelle flushen
iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X
iptables -t nat -X
iptables -t mangle -X
# Default-Policies setzen
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
# MY_REJECT-Chain
iptables -N MY_REJECT
# MY_REJECT fuellen
iptables -A MY_REJECT -p tcp -m limit --limit 7200/h -j LOG --log-prefix "REJECT TCP "
iptables -A MY_REJECT -p tcp -j REJECT --reject-with tcp-reset
iptables -A MY_REJECT -p udp -m limit --limit 7200/h -j LOG --log-prefix "REJECT UDP "
iptables -A MY_REJECT -p udp -j REJECT --reject-with icmp-port-unreachable
iptables -A MY_REJECT -p icmp -m limit --limit 7200/h -j LOG --log-prefix "DROP ICMP "
iptables -A MY_REJECT -p icmp -j DROP
iptables -A MY_REJECT -m limit --limit 7200/h -j LOG --log-prefix "REJECT OTHER "
iptables -A MY_REJECT -j REJECT --reject-with icmp-proto-unreachable
# MY_DROP-Chain
iptables -N MY_DROP
iptables -A MY_DROP -m limit --limit 7200/h -j LOG --log-prefix "PORTSCAN DROP "
iptables -A MY_DROP -j DROP
# Alle verworfenen Pakete protokollieren
iptables -A INPUT -m state --state INVALID -m limit --limit 7200/h -j LOG --log-prefix "INPUT INVALID "
iptables -A OUTPUT -m state --state INVALID -m limit --limit 7200/h -j LOG --log-prefix "OUTPUT INVALID "
# Korrupte Pakete zurueckweisen
iptables -A INPUT -m state --state INVALID -j DROP
iptables -A OUTPUT -m state --state INVALID -j DROP
# Stealth Scans etc. DROPpen
# Keine Flags gesetzt
iptables -A INPUT -p tcp --tcp-flags ALL NONE -j MY_DROP
# SYN und FIN gesetzt
iptables -A INPUT -p tcp --tcp-flags SYN,FIN SYN,FIN -j MY_DROP
# SYN und RST gleichzeitig gesetzt
iptables -A INPUT -p tcp --tcp-flags SYN,RST SYN,RST -j MY_DROP
# FIN und RST gleichzeitig gesetzt
iptables -A INPUT -p tcp --tcp-flags FIN,RST FIN,RST -j MY_DROP
# FIN ohne ACK
iptables -A INPUT -p tcp --tcp-flags ACK,FIN FIN -j MY_DROP
# PSH ohne ACK
iptables -A INPUT -p tcp --tcp-flags ACK,PSH PSH -j MY_DROP
# URG ohne ACK
iptables -A INPUT -p tcp --tcp-flags ACK,URG URG -j MY_DROP
# Loopback-Netzwerk-Kommunikation zulassen
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Connection-Tracking aktivieren
iptables -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# FTP
iptables -A INPUT -i dsl1 -m state --state NEW,ESTABLISHED -p tcp --dport 21 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 21 -m state --state NEW,ESTABLISHED -- ACCEPT
# SSH
iptables -A INPUT -i dsl1 -m state --state NEW,ESTABLISHED -p tcp --dport 22 -j ACCEPT
# HALF-LIFE
iptables -A INPUT -i dsl1 -m state --state NEW -p tcp --dport 6000:6003 -j ACCEPT
iptables -A INPUT -i dsl1 -m state --state NEW -p tcp --dport 7001:7002 -j ACCEPT
iptables -A INPUT -i dsl1 -m state --state NEW -p udp --dport 27005 -j ACCEPT
iptables -A INPUT -i dsl1 -m state --state NEW -p udp --dport 27010 -j ACCEPT
iptables -A INPUT -i dsl1 -m state --state NEW -p udp --dport 27015:27017 -j ACCEPT
# Default-Policies mit REJECT
iptables -A INPUT -j MY_REJECT
iptables -A OUTPUT -j MY_REJECT
# Max. 500/Sekunde (5/Jiffie) senden
echo 5 > /proc/sys/net/ipv4/icmp_ratelimit
# Speicherallozierung und -timing für IP-De/-Fragmentierung
echo 262144 > /proc/sys/net/ipv4/ipfrag_high_thresh
echo 196608 > /proc/sys/net/ipv4/ipfrag_low_thresh
echo 30 > /proc/sys/net/ipv4/ipfrag_time
# TCP-FIN-Timeout zum Schutz vor DoS-Attacken setzen
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout
# Maximal 3 Antworten auf ein TCP-SYN
echo 3 > /proc/sys/net/ipv4/tcp_retries1
# TCP-Pakete maximal 15x wiederholen
echo 15 > /proc/sys/net/ipv4/tcp_retries2
;;
stop)
echo "Stoppe IP-Paketfilter"
# Tabelle flushen
iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -X
iptables -t nat -X
iptables -t mangle -X
# Default-Policies setzen
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
;;
status)
echo "Tabelle filter"
iptables -L -vn
echo "Tabelle nat"
iptables -t nat -L -vn
echo "Tabelle mangle"
iptables -t mangle -L -vn
;;
*)
echo "Fehlerhafter Aufruf"
echo "Syntax: $0 {start|stop|status}"
exit 1
;;
esac
