#!/bin/sh
#
# rc.firewall-2.4-stronger

echo -e "\nLoading custom rc.firewall...\n"

# Variable Definitions
IPTABLES=/usr/local/sbin/iptables
LSMOD=/sbin/lsmod
DEPMOD=/sbin/depmod
INSMOD=/sbin/insmod
GREP=/bin/grep
AWK=/usr/bin/awk
SED=/usr/bin/sed
IFCONFIG=/sbin/ifconfig
EXTIF="eth0"
INTIF="eth1"
EXTIP="`$IFCONFIG $EXTIF | $GREP 'inet addr' | $AWK '{print $2}' | \
$SED -e 's/.*://'`"
INTNET="192.168.192.0/24"
INTIP="192.168.192.249/24"
UNIVERSE="0.0.0.0/0"


echo "  - Verifying that all kernel modules are ok"
$DEPMOD -a

echo -en "    Loading kernel modules: "

if [ -z "` $LSMOD | $GREP ip_tables | $AWK {'print $1'} `" ]; then
   $INSMOD ip_tables
fi


if [ -z "` $LSMOD | $GREP ip_conntrack | $AWK {'print $1'} `" ]; then
   $INSMOD ip_conntrack
fi

if [ -z "` $LSMOD | $GREP ip_conntrack_ftp | $AWK {'print $1'} `" ]; then
   $INSMOD ip_conntrack_ftp
fi

if [ -z "` $LSMOD | $GREP ip_conntrack_irc | $AWK {'print $1'} `" ]; then
   $INSMOD ip_conntrack_irc
fi


#Load the general IPTABLES NAT code - "iptable_nat"
#  - Loaded automatically when MASQ functionality is turned on
# 
#  - Loaded manually to clean up kernel auto-loading timing issues
#
echo -en "iptable_nat, "
#
#Verify the module isn't loaded.  If it is, skip it
#
if [ -z "` $LSMOD | $GREP iptable_nat | $AWK {'print $1'} `" ]; then
   $INSMOD iptable_nat
fi

if [ -z "` $LSMOD | $GREP ip_nat_ftp | $AWK {'print $1'} `" ]; then
   $INSMOD ip_nat_ftp
fi

echo "  ---"

echo "  Enabling forwarding.."
echo "1" > /proc/sys/net/ipv4/ip_forward

echo "  Clearing any existing rules and setting default policy to DROP.."
$IPTABLES -P INPUT DROP  
$IPTABLES -F INPUT 
$IPTABLES -P OUTPUT DROP  
$IPTABLES -F OUTPUT 
$IPTABLES -P FORWARD DROP
$IPTABLES -F FORWARD 
$IPTABLES -F -t nat

if [ -n "`$IPTABLES -L | $GREP drop-and-log-it`" ]; then
   $IPTABLES -F drop-and-log-it
fi

$IPTABLES -X

$IPTABLES -Z

$IPTABLES -N drop-and-log-it
$IPTABLES -A drop-and-log-it -j LOG --log-level info 
$IPTABLES -A drop-and-log-it -j DROP

echo -e "\n   - Loading INPUT rulesets"


#######################################################################
# INPUT: Incoming traffic from various interfaces.  All rulesets are 
#        already flushed and set to a default policy of DROP. 
#

# loopback interfaces are valid.
#
$IPTABLES -A INPUT -i lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT


# local interface, local machines, going anywhere is valid
#
$IPTABLES -A INPUT -i $INTIF -s $INTNET -d $UNIVERSE -j ACCEPT


# remote interface, claiming to be local machines, IP spoofing, get lost
#
$IPTABLES -A INPUT -i $EXTIF -s $INTNET -d $UNIVERSE -j drop-and-log-it


# external interface, from any source, for ICMP traffic is valid
#
#  If you would like your machine to "ping" from the Internet, 
#  enable this next line
#
$IPTABLES -A INPUT -i $EXTIF -p ICMP -s $UNIVERSE -d $EXTIP -j ACCEPT


# remote interface, any source, going to permanent PPP address is valid
#
#$IPTABLES -A INPUT -i $EXTIF -s $UNIVERSE -d $EXTIP -j ACCEPT

# Allow ssh & ftp (not telnet though)
$IPTABLES -A INPUT -p TCP -s $UNIVERSE --dport 21 -j ACCEPT
$IPTABLES -A INPUT -p TCP -s $UNIVERSE --dport 22 -j ACCEPT
$IPTABLES -A INPUT -p TCP -s $UNIVERSE --dport 113 -j ACCEPT

# Allow port 25 (smtp)
$IPTABLES -A INPUT -p TCP -s $UNIVERSE --dport 25 -j ACCEPT

# Allow any related traffic coming back to the MASQ server in
#
$IPTABLES -A INPUT -i $EXTIF -s $UNIVERSE -d $EXTIP -m state --state \
ESTABLISHED,RELATED -j ACCEPT


# ----- Begin OPTIONAL Section -----
#

# DHCPd - Enable the following lines if you run an INTERNAL DHCPd server
#
#$IPTABLES -A INPUT -i $INTIF -p tcp --sport 68 --dport 67 -j ACCEPT
#$IPTABLES -A INPUT -i $INTIF -p udp --sport 68 --dport 67 -j ACCEPT

# HTTPd - Enable the following lines if you run an EXTERNAL WWW server
#
#echo -e "      - Allowing EXTERNAL access to the WWW server"
$IPTABLES -A INPUT -i $EXTIF -m state --state NEW,ESTABLISHED,RELATED \
-p tcp -s $UNIVERSE -d $EXTIP --dport 80 -j ACCEPT

#
# ----- End OPTIONAL Section -----



# Catch all rule, all other incoming is denied and logged.
#
$IPTABLES -A INPUT -p udp --sport 500 --dport 500 -j ACCEPT
$IPTABLES -A INPUT -p 50 -j ACCEPT
$IPTABLES -A INPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it


echo -e "   - Loading OUTPUT rulesets"

#######################################################################
# OUTPUT: Outgoing traffic from various interfaces.  All rulesets are
#         already flushed and set to a default policy of DROP.
#

# loopback interface is valid.
#
$IPTABLES -A OUTPUT -o lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT


# local interfaces, any source going to local net is valid
#
$IPTABLES -A OUTPUT -o $INTIF -s $EXTIP -d $INTNET -j ACCEPT


# local interface, any source going to local net is valid
#
$IPTABLES -A OUTPUT -o $INTIF -s $INTIP -d $INTNET -j ACCEPT


# outgoing to local net on remote interface, stuffed routing, deny
#
$IPTABLES -A OUTPUT -o $EXTIF -s $UNIVERSE -d $INTNET -j drop-and-log-it


# anything else outgoing on remote interface is valid
#
$IPTABLES -A OUTPUT -o $EXTIF -s $EXTIP -d $UNIVERSE -j ACCEPT


# ----- Begin OPTIONAL Section -----
#

# DHCPd - Enable the following lines if you run an INTERNAL DHCPd server
#
#$IPTABLES -A OUTPUT -o $INTIF -p tcp -s $INTIP --sport 67 -d 255.255.255.255 --dport 68 -j ACCEPT
#$IPTABLES -A OUTPUT -o $INTIF -p udp -s $INTIP --sport 67 -d 255.255.255.255 --dport 68 -j ACCEPT

#
# ----- End OPTIONAL Section -----

# Catch all rule, all other outgoing is denied and logged.
#
$IPTABLES -A OUTPUT -p udp --sport 500 --dport 500 -j ACCEPT
$IPTABLES -A OUTPUT -p 50 -j ACCEPT
$IPTABLES -A OUTPUT -s $UNIVERSE -d $UNIVERSE -j drop-and-log-it


echo -e "   - Loading FORWARD rulesets"

#######################################################################
# FORWARD: Enable Forwarding and thus IPMASQ
#

echo "     - FWD: Allow all connections OUT and only existing/related IN"
$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT

$IPTABLES -A FORWARD -j drop-and-log-it


#echo "     - NAT: Enabling SNAT (MASQUERADE) functionality on $EXTIF"
#
#More liberal form
#$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
#
#Stricter form
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j SNAT --to $EXTIP




echo -e "\nStronger rc.firewall-2.4 $FWVER done.\n"