#!/bin/sh
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local
#/sbin/insmod e100
#/sbin/ifup eth1
ROUTER=`grep routers /var/lib/dhclient/dhclient-eth0.leases | head -1 | awk \
'{print $NF}' | sed 's/;//g'`
route add default gw "$ROUTER"
#
# Sun Apr  3 09:11:44 EDT 2005
##############################
#
IPTABLES="/sbin/iptables"
INET_IFACE="eth0"
OSPREY="192.168.252.3"
INET_IP=`ifconfig eth0 | grep 'inet addr' | awk -F":" '{print $2}' | sed 's/  Bcast//'`
LAN_IP="192.168.252.5"
DHCP="yes"
DHCP_SERVER=`grep dhcp-server-identifier /var/lib/dhclient/dhclient-eth0.leases \
| head -1 | awk '{print $NF}' | sed 's/;//g'`
LAN_IP_RANGE="192.168.252.0/24"
LAN_BROADCAST_ADDRESS="192.168.252.255"
LAN_IFACE="eth0"
LO_IFACE="lo"
LO_IP="127.0.0.1"

# 2. Module loading.
/sbin/depmod -a
# 2.1 Required modules
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_tables
/sbin/modprobe iptable_filter
/sbin/modprobe iptable_mangle
/sbin/modprobe iptable_nat
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_MASQUERADE
# 2.2 Non-Required modules
#/sbin/modprobe ipt_owner
#/sbin/modprobe ipt_REJECT
/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc
/sbin/modprobe ip_nat_ftp
#/sbin/modprobe ip_nat_irc

# 3. /proc set up.
#Disabling IP Spoofing attacks.
echo 2 > /proc/sys/net/ipv4/conf/all/rp_filter
#Don't respond to broadcast pings (Smurf-Amplifier-Protection)
echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
#Block source routing
echo 0 > /proc/sys/net/ipv4/conf/all/accept_source_route
#Kill timestamps
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
#Enable SYN Cookies
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
#Kill redirects
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects
#Enable bad error message protection
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
#Log martians (packets with impossible addresses)
echo 1 > /proc/sys/net/ipv4/conf/all/log_martians

# 3.2 Non-Required proc configuration
#echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter
#echo "1" > /proc/sys/net/ipv4/conf/all/proxy_arp
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr

# 4. rules set up.
# 4.1 Filter table
# 4.1.1 Set policies

/sbin/iptables -P INPUT DROP
/sbin/iptables -P OUTPUT DROP
/sbin/iptables -P FORWARD DROP

# 4.1.2 Create userspecified chains
# Create chain for bad tcp packets

/sbin/iptables -N bad_tcp_packets

# Create separate chains for ICMP, TCP and UDP to traverse

/sbin/iptables -N allowed
/sbin/iptables -N tcp_packets
/sbin/iptables -N udpincoming_packets
/sbin/iptables -N icmp_packets

# 4.1.3 Create content in userspecified chains
# bad_tcp_packets chain

/sbin/iptables -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \
--log-prefix "New not syn:"
/sbin/iptables -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP

# allowed chain
/sbin/iptables -A allowed -p TCP --syn -j ACCEPT
/sbin/iptables -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A allowed -p TCP -j DROP

# UDP ports
/sbin/iptables -A udpincoming_packets -p UDP -s 0/0 --source-port 53 -j ACCEPT
if [ $DHCP == "yes" ] ; then
 /sbin/iptables -A udpincoming_packets -p UDP -s $DHCP_SERVER --sport 67 \
 --dport 68 -j ACCEPT
fi

# ICMP rules
/sbin/iptables -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
/sbin/iptables -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT

# 4.1.4 INPUT chain
# Bad TCP packets we don't want.
/sbin/iptables -A INPUT -p tcp -j bad_tcp_packets

# Rules for special networks not part of the Internet
/sbin/iptables -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
/sbin/iptables -A INPUT -p ALL -i $LO_IFACE -j ACCEPT
/sbin/iptables -A INPUT -p ALL -i $LAN_IFACE -d $LAN_BROADCAST_ADDRESS -j ACCEPT

# Special rule for DHCP requests from LAN, which are not caught properly 
# otherwise.
/sbin/iptables -A INPUT -p UDP -i $LAN_IFACE --dport 67 --sport 68 -j ACCEPT

# Rules for incoming packets from the internet.
/sbin/iptables -A INPUT -p ALL -i $INET_IFACE -m state --state \
ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
/sbin/iptables -A INPUT -p UDP -i $INET_IFACE -j udpincoming_packets
/sbin/iptables -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets

# Log weird packets that don't match the above.
/sbin/iptables -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT INPUT packet died: "

# 4.1.5 FORWARD chain
# Bad TCP packets we don't want
/sbin/iptables -A FORWARD -p tcp -j bad_tcp_packets

# Accept the packets we actually want to forward
/sbin/iptables -A FORWARD -i $LAN_IFACE -j ACCEPT
/sbin/iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A FORWARD -o $INET_IFACE -s $OSPREY -p tcp --sport 22 \
 -j ACCEPT

# Log weird packets that don't match the above.
/sbin/iptables -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT FORWARD packet died: "

# 4.1.6 OUTPUT chain

# Bad TCP packets we don't want.
/sbin/iptables -A OUTPUT -p tcp -j bad_tcp_packets

# Special OUTPUT rules to decide which IP's to allow.
/sbin/iptables -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
/sbin/iptables -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
/sbin/iptables -A OUTPUT -p ALL -o $INET_IFACE -j ACCEPT

# Log weird packets that don't match the above.
/sbin/iptables -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT OUTPUT packet died: "

# 4.2 nat table
/sbin/iptables -t nat -A OUTPUT -p tcp -d $INET_IP --dport 22 -j DNAT \
--to-destination $OSPREY

# 4.2.4 PREROUTING chain
/sbin/iptables -t nat -A PREROUTING --dst $INET_IP -p tcp --dport 22 -j DNAT \
--to-destination $OSPREY
#
# 4.2.5 POSTROUTING chain
# Enable simple IP Forwarding and Network Address Translation
#
/sbin/iptables -t nat -A POSTROUTING -p tcp --dst $OSPREY --dport 22 -j \
SNAT --to-source $LAN_IP
/sbin/iptables -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE 
#
# turn on packet forwarding last of all
echo "1" > /proc/sys/net/ipv4/ip_forward