#!/bin/sh

# minifirewall is shellscripts for easy firewalling on a standalone server
# we used netfilter/iptables http://netfilter.org/ designed for recent Linux kernel
# See https://forge.evolix.org/projects/minifirewall

# Copyright (c) 2007-2015 Evolix
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 3
# of the License.

# Description
# script for standalone server

# Start or stop minifirewall
#

### BEGIN INIT INFO
# Provides:          minfirewall
# Required-Start:
# Required-Stop:
# Should-Start:      $network $syslog $named
# Should-Stop:       $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: start and stop the firewall
# Description:       Firewall designed for standalone server
### END INIT INFO

DESC="minifirewall"
NAME="minifirewall"


# Variables configuration
#########################

# iptables paths
IPT=/sbin/iptables
IPT6=/sbin/ip6tables

# TCP/IP variables
LOOPBACK='127.0.0.0/8'
LOOPBACK6='::1'
CLASSA='10.0.0.0/8'
CLASSB='172.16.0.0/12'
CLASSC='192.168.0.0/16'
CLASSD='224.0.0.0/4'
CLASSE='240.0.0.0/5'
ALL='0.0.0.0'
BROAD='255.255.255.255'
PORTSROOT='0:1023'
PORTSUSER='1024:65535'


ipxtables() {
	set +e
        ip=$1
        echo "$ip"|grep -q ":"
        if [ $? -ne 0 ]; then
                echo $IPT
        else
                echo $IPT6
        fi
	set -e
}

ipalltables() {
	iptables $@
	ip6tables $@
}

check_addr() {
	set +e
        addr=$1
	echo $addr|grep -q "/"
	if [ $? -eq 0 ]; then
		echo $addr
	else
	        host=$(host $addr)
	        if [ $? -ne 0 ]; then
	                echo "WARNING: $addr is invalid !" >&2
	        else
	                echo "$host"|grep -q "address"
	                if [ $? -eq 0 ]; then
	                        echo "$host"|grep -v "mail"|awk '{ print $NF }'|while read ip; do
	                                echo $ip
	                        done
	                else
	                        echo $addr
	                fi
	        fi
	fi
	set -e
}

case "$1" in
 start)

     echo "Start IPTables rules..."

# Stop and warn if error!
set -e
trap 'echo "ERROR in minifirewall configuration (fix it now!) or script manipulation (fix yourself)." ' INT TERM EXIT


# sysctl network security settings
##################################

# Don't answer to broadcast pings
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts

# Ignore bogus ICMP responses
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses

# Disable Source Routing
for i in /proc/sys/net/ipv4/conf/*/accept_source_route; do
echo 0 > $i
done

# Enable TCP SYN cookies to avoid TCP-SYN-FLOOD attacks
# cf http://cr.yp.to/syncookies.html
echo 1 > /proc/sys/net/ipv4/tcp_syncookies

# Disable ICMP redirects
for i in /proc/sys/net/ipv4/conf/*/accept_redirects; do
echo 0 > $i
done

for i in /proc/sys/net/ipv4/conf/*/send_redirects; do
echo 0 > $i
done

# Enable Reverse Path filtering : verify if responses use same network interface
for i in /proc/sys/net/ipv4/conf/*/rp_filter; do
echo 1 > $i
done

# log des paquets avec adresse incoherente
for i in /proc/sys/net/ipv4/conf/*/log_martians; do
echo 1 > $i
done

# IPTables configuration
########################

ipalltables -N LOG_DROP
ipalltables -A LOG_DROP -j LOG  #--log-prefix '[IPTABLES DROP] : '
ipalltables -A LOG_DROP -j DROP
ipalltables -N LOG_ACCEPT
ipalltables -A LOG_ACCEPT -j LOG  #--log-prefix '[IPTABLES ACCEPT] : '
ipalltables -A LOG_ACCEPT -j ACCEPT

# Configuration
oldconfigfile="/etc/firewall.rc"
configfile="/etc/default/minifirewall"

if test -f $oldconfigfile; then
    echo "$oldconfigfile is deprecated, rename to $configfile" >&2
    exit 1
fi

if ! test -f $configfile; then
    echo "$configfile does not exist" >&2
    exit 1
fi

tmpfile=`mktemp`
. $configfile 2>$tmpfile >&2
if [ -s $tmpfile ]; then
        echo "$configfile returns standard or error output (see below). Stopping." >&2
        cat $tmpfile
        exit 1
fi
rm $tmpfile

# Trusted ip addresses
ipalltables -N ONLYTRUSTED
ipalltables -A ONLYTRUSTED -j LOG_DROP
for addr in $TRUSTEDIPS; do
        check_addr $addr|while read ip; do
                $(ipxtables $ip) -I ONLYTRUSTED -s $ip -j ACCEPT
        done
done

# Privilegied ip addresses
# (trusted ip addresses *are* privilegied)
ipalltables -N ONLYPRIVILEGIED
ipalltables -A ONLYPRIVILEGIED -j ONLYTRUSTED
for addr in $PRIVILEGIEDIPS; do
        check_addr $addr|while read ip; do
                $(ipxtables $ip) -I ONLYPRIVILEGIED -s $ip -j ACCEPT
        done
done

# Chain for restrictions (blacklist IPs/ranges)
ipalltables -N NEEDRESTRICT

# We allow all on loopback interface
ipalltables -A INPUT -i lo -j ACCEPT
# if OUTPUTDROP
ipalltables -A OUTPUT -o lo -j ACCEPT

# We avoid "martians" packets, typical when W32/Blaster virus
# attacked windowsupdate.com and DNS was changed to 127.0.0.1
# ipalltables -t NAT -I PREROUTING -s $LOOPBACK -i ! lo -j DROP
$IPT -A INPUT -s $LOOPBACK ! -i lo -j DROP
$IPT6 -A INPUT -s $LOOPBACK6 ! -i lo -j DROP


# Local services restrictions
#############################

# Allow services for $INTLAN (local server or local network)
$IPT -A INPUT -s $INTLAN -j ACCEPT

# Enable protection chain for sensible services
for x in $SERVICESTCP1p
    do
        ipalltables -A INPUT -p tcp --dport $x -j NEEDRESTRICT
    done

for x in $SERVICESUDP1p
    do
        ipalltables -A INPUT -p udp --dport $x -j NEEDRESTRICT
    done

# Public service
for x in $SERVICESTCP1
    do
        ipalltables -A INPUT -p tcp --dport $x -j ACCEPT
    done

for x in $SERVICESUDP1
    do
        ipalltables -A INPUT -p udp --dport $x -j ACCEPT
    done

# Privilegied services
for x in $SERVICESTCP2
    do
        ipalltables -A INPUT -p tcp --dport $x -j ONLYPRIVILEGIED
    done

for x in $SERVICESUDP2
    do
        ipalltables -A INPUT -p udp --dport $x -j ONLYPRIVILEGIED
    done

# Private services
for x in $SERVICESTCP3
    do
        ipalltables -A INPUT -p tcp --dport $x -j ONLYTRUSTED
    done

for x in $SERVICESUDP3
    do
        ipalltables -A INPUT -p udp --dport $x -j ONLYTRUSTED
    done


# External services
###################

# DNS authorizations
for x in $DNSSERVEURS
    do
        ipalltables -A INPUT -p tcp ! --syn --sport 53 --dport $PORTSUSER -s $x -j ACCEPT
        ipalltables -A INPUT -p udp --sport 53 --dport $PORTSUSER -s $x -m state --state ESTABLISHED,RELATED -j ACCEPT
        ipalltables -A OUTPUT -o $INT -p udp -d $x --dport 53 --match state --state NEW -j ACCEPT
    done

# HTTP (TCP/80) authorizations
for addr in $HTTPSITES
    do
	check_addr $addr|while read ip; do
                $(ipxtables $ip) -A INPUT -p tcp ! --syn --sport 80 --dport $PORTSUSER -s $ip -j ACCEPT
        done
    done

# HTTPS (TCP/443) authorizations
for addr in $HTTPSSITES
    do
	check_addr $addr|while read ip; do
                $(ipxtables $ip) -A INPUT -p tcp ! --syn --sport 443 --dport $PORTSUSER -s $ip -j ACCEPT
        done
    done

# FTP (so complex protocol...) authorizations
for x in $FTPSITES
    do
        # requests on Control connection
        ipalltables -A INPUT -p tcp ! --syn --sport 21 --dport $PORTSUSER -s $x -j ACCEPT
        # FTP port-mode on Data Connection
        ipalltables -A INPUT -p tcp --sport 20 --dport $PORTSUSER -s $x -j ACCEPT
        # FTP passive-mode on Data Connection
        # WARNING, this allow all connections on TCP ports > 1024
        ipalltables -A INPUT -p tcp ! --syn --sport $PORTSUSER --dport $PORTSUSER -s $x -j ACCEPT
    done

# SSH authorizations
for x in $SSHOK
        do
                ipalltables -A INPUT -p tcp ! --syn --sport 22 -s $x -j ACCEPT
        done

# SMTP authorizations
for addr in $SMTPOK
    do
	check_addr $addr|while read ip; do
                $(ipxtables $ip) -A INPUT -p tcp ! --syn --sport 25 --dport $PORTSUSER -s $ip -j ACCEPT
        done
    done

# secure SMTP (TCP/465 et TCP/587) authorizations
for addr in $SMTPSECUREOK
    do
	check_addr $addr|while read ip; do
                $(ipxtables $ip) -A INPUT -p tcp ! --syn --sport 465 --dport $PORTSUSER -s $ip -j ACCEPT
                $(ipxtables $ip) -A INPUT -p tcp ! --syn --sport 587 --dport $PORTSUSER -s $ip -j ACCEPT
        done
    done

# NTP authorizations
for x in $NTPOK
        do
            ipalltables -A INPUT -p udp --sport 123 -s $x -j ACCEPT
            ipalltables -A OUTPUT -o $INT -p udp -d $x --dport 123 --match state --state NEW -j ACCEPT
        done

# Always allow ICMP
ipalltables -A INPUT -p icmp -j ACCEPT


# IPTables policy
#################

# by default DROP INPUT packets
ipalltables -P INPUT DROP

# by default, no FORWARING (deprecated for Virtual Machines)
#echo 0 > /proc/sys/net/ipv4/ip_forward
#ipalltables -P FORWARD DROP
#ipalltables6 -P FORWARD DROP

# by default allow OUTPUT packets... but drop UDP packets (see OUTPUTDROP to drop OUTPUT packets)
ipalltables -P OUTPUT ACCEPT
ipalltables -A OUTPUT -o $INT -p udp --dport 33434:33523 --match state --state NEW -j ACCEPT
ipalltables -A OUTPUT -p udp --match state --state ESTABLISHED,RELATED -j ACCEPT
ipalltables -A OUTPUT -p udp -j DROP

trap - INT TERM EXIT

    echo "...starting IPTables rules is now finish : OK"
  ;;

  stop)

    echo "Flush all rules and accept everything..."

    # Delete all rules
    ipalltables -F INPUT
    ipalltables -F OUTPUT
    ipalltables -F LOG_DROP
    ipalltables -F LOG_ACCEPT
    ipalltables -F ONLYTRUSTED
    ipalltables -F ONLYPRIVILEGIED
    ipalltables -F NEEDRESTRICT
    ipalltables -t nat -F
    ipalltables -t mangle -F

    # Accept all
    ipalltables -P INPUT ACCEPT
    ipalltables -P OUTPUT ACCEPT
    #ipalltables -P FORWARD ACCEPT
    #ipalltables -t nat -P PREROUTING ACCEPT
    #ipalltables -t nat -P POSTROUTING ACCEPT

    # Delete non-standard chains
    ipalltables -X LOG_DROP
    ipalltables -X LOG_ACCEPT
    ipalltables -X ONLYPRIVILEGIED
    ipalltables -X ONLYTRUSTED
    ipalltables -X NEEDRESTRICT

    echo "...flushing IPTables rules is now finish : OK"
  ;;

  status)

    ipalltables -L -n -v --line-numbers
    ipalltables -t nat -L -n -v --line-numbers
    ipalltables -t mangle -L -n -v --line-numbers
  ;;

  reset)

    echo "Reset all IPTables counters..."

    ipalltables -Z
    ipalltables -t nat -Z
    ipalltables -t mangle -Z

    echo "...reseting IPTables counters is now finish : OK"
  ;;

  restart)

    $0 stop
    $0 start
  ;;

  *)

    echo "Usage: $0 {start|stop|restart|status|reset|squid}"
    exit 1
esac

exit 0