Setting Firewall dan Redirect Proxy Server di Linux Debian

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

SYSCTL="/sbin/sysctl -w"
IPT="/sbin/iptables"

# Internet Interface
INET_IFACE="eth0"

# Local Interface Information
LOCAL_IFACE="eth1"
LOCAL_IP="192.168.0.254"
LOCAL_NET="192.168.0.0/24"
LOCAL_BCAST="192.168.0.255"

# Localhost Interface
LO_IFACE="lo"
LO_IP="127.0.0.1"

# Load Modules
/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_nat_ftp
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_conntrack_irc


# Kernel Parameter Configuration
    echo "1" > /proc/sys/net/ipv4/ip_forward
    echo "1" > /proc/sys/net/ipv4/tcp_syncookies
    echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter
    echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
    echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route
    echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
    echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route
    echo "1" > /proc/sys/net/ipv4/conf/all/secure_redirects
    echo "1" > /proc/sys/net/ipv4/conf/all/log_martians

# Reset Default Policies
$IPT -P INPUT ACCEPT
$IPT -P FORWARD ACCEPT
$IPT -P OUTPUT ACCEPT
$IPT -t nat -P PREROUTING ACCEPT
$IPT -t nat -P POSTROUTING ACCEPT
$IPT -t nat -P OUTPUT ACCEPT
$IPT -t mangle -P PREROUTING ACCEPT
$IPT -t mangle -P OUTPUT ACCEPT

# Flush All Rules
$IPT -F
$IPT -t nat -F
$IPT -t mangle -F

# Erase All Non-Default Chains
$IPT -X
$IPT -t nat -X
$IPT -t mangle -X


# User-Specified Chains
$IPT -N bad_packets
$IPT -N bad_tcp_packets
$IPT -N icmp_packets
$IPT -N udp_inbound
$IPT -N udp_outbound
$IPT -N tcp_inbound
$IPT -N tcp_outbound



# Nat Table
$IPT -t nat -A PREROUTING -p tcp --destination-port 80 -j REDIRECT --to-ports 8080
$IPT -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE


exit 0