#!/bin/bash
# ---------------------------------------------------------------------
# Linux-iptables-Firewallskript, Copyright (c) 2010 under the GPL
# Autogenerated by iptables Generator v1.22 (c) 2002-2010 by Harald Bertram
# Please visit http://harry.homelinux.org for new versions of
# the iptables Generator (c).
# 
# This Script was generated by request from:
# micha_doe@arcor.de on: 2010-2-24 13:29.38 MET.
# 
# 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

    # ICMP Echo-Request (ping) zulassen und beantworten
    iptables -A INPUT -m state --state NEW -p icmp --icmp-type echo-request -j ACCEPT

    # LAN-Zugriff auf eth1
    iptables -A INPUT -m state --state NEW -i eth1 -j ACCEPT

    # Default-Policies mit REJECT
    iptables -A INPUT -j MY_REJECT
    iptables -A OUTPUT -j MY_REJECT

    # Masquerading
    iptables -t nat -A POSTROUTING -o dsl0 -j MASQUERADE

    # SYN-Cookies
    echo 1 > /proc/sys/net/ipv4/tcp_syncookies 2> /dev/null
    
    # Forwarding/Routing
    echo "Aktiviere IP-Routing"
    echo 1 > /proc/sys/net/ipv4/ip_forward 2> /dev/null


    # Stop Source-Routing
    for i in /proc/sys/net/ipv4/conf/*; do echo 0 > $i/accept_source_route 2> /dev/null; done

    # Stop Redirecting
    for i in /proc/sys/net/ipv4/conf/*; do echo 0 > $i/accept_redirects 2> /dev/null; done

    # Reverse-Path-Filter
    for i in /proc/sys/net/ipv4/conf/*; do echo 2 > $i/rp_filter 2> /dev/null; done

    # Log Martians
    for i in /proc/sys/net/ipv4/conf/*; do echo 1 > $i/log_martians 2> /dev/null; done

    # BOOTP-Relaying ausschalten
    for i in /proc/sys/net/ipv4/conf/*; do echo 0 > $i/bootp_relay 2> /dev/null; done

    # Proxy-ARP ausschalten
    for i in /proc/sys/net/ipv4/conf/*; do echo 0 > $i/proxy_arp 2> /dev/null; done

    # Ungltige ICMP-Antworten ignorieren
    echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses 2> /dev/null

    # ICMP Echo-Broadcasts ignorieren
    echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts 2> /dev/null

    # Max. 500/Sekunde (5/Jiffie) senden
    echo 5 > /proc/sys/net/ipv4/icmp_ratelimit

    # Speicherallozierung und -timing fr 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
