[FoLUG]Aiuto con iptables
Andrea Chiumenti
folug@lists.linux.it
Mon, 06 May 2002 08:57:28 +0200
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Salva a tutti.
Sapreste dirmi perche' con il mio script non riesco a reindirizzare le
richieste al web server?
Ho un router di mezzo se vi puņ interessare.
Ciaooo,
kiuma
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#!/bin/sh
#
# rc.firewall - Initial SIMPLE IP Firewall script for Linux 2.4.x and iptables
#
# Copyright (C) 2001 Oskar Andreasson <blueflux@koffein.net>
#
# 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; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program or from the site that you downloaded it
# from; if not, write to the Free Software Foundation, Inc., 59 Temple
# Place, Suite 330, Boston, MA 02111-1307 USA
#
###########################################################################
#
# 1. Configuration options.
#
###########################################################################
#
# Local Area Network configuration.
#
# your LAN's IP range and localhost IP. /24 means to only use the first 24
# bits of the 32 bit IP adress. the same as netmask 255.255.255.0
#
LAN_IP="192.168.100.5"
LAN_IP_RANGE="192.168.100.0/24"
LAN_BCAST_ADRESS="192.168.100.255"
LAN_IFACE="eth0"
###########################################################################
#
# Localhost Configuration.
#
LO_IFACE="lo"
LO_IP="127.0.0.1"
###########################################################################
#
# Internet Configuration.
#
INET_IP="62.94.113.22"
INET_IFACE="eth1"
###########################################################################
#
# IPTables Configuration.
#
IPTABLES="/sbin/iptables"
###########################################################################
#
# 2. Module loading.
#
#
# Needed to initially load modules
#
#/sbin/depmod -a
#
# Adds some iptables targets like LOG, REJECT and MASQUARADE.
#
/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_REJECT
#/sbin/modprobe ipt_MASQUERADE
#
# Support for owner matching
#
#/sbin/modprobe ipt_owner
#
# Support for connection tracking of FTP and IRC.
#
#/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc
###########################################################################
#
# 3. /proc set up.
#
# Enable ip_forward if you have two or more networks, including the
# Internet, that needs forwarding of packets through this box. This is
# critical since it is turned off as default in Linux.
#
echo "1" > /proc/sys/net/ipv4/ip_forward
#
# Dynamic IP users:
#
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr
###########################################################################
#
# Flushing IPtables
##########################################
### reset the default policies
### in the filter table
##########################################
$IPTABLES -P INPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT
$IPTABLES -P OUTPUT ACCEPT
#######################################
### reset the default
### policies in the nat table
#######################################
$IPTABLES -t nat -P PREROUTING ACCEPT
$IPTABLES -t nat -P POSTROUTING ACCEPT
$IPTABLES -t nat -P OUTPUT ACCEPT
################################
### flush all chains
################################
$IPTABLES -F
$IPTABLES -t nat -F
################################
### erase all not default chains
################################
$IPTABLES -X
$IPTABLES -t nat -X
###########################################################################
#
# 4. IPTables rules set up.
#
# Set default policies for the INPUT, FORWARD and OUTPUT chains.
#
$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP
#
# bad_tcp_packets chain
#
# Take care of bad TCP packets that we don't want.
#
$IPTABLES -N bad_tcp_packets
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \
--log-prefix "New not syn:"
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP
#
# Do some checks for obviously spoofed IP's
#
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 192.168.0.0/16 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 10.0.0.0/8 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 172.16.0.0/12 -j DROP
#
# Enable simple IP Forwarding and Network Address Translation
#
$IPTABLES -t nat -A PREROUTING -p TCP -i $INET_IFACE -d 62.94.113.22 --dport 80 -j DNAT --to-destination 192.168.100.1:80
$IPTABLES -t nat -A PREROUTING -p TCP -i $INET_IFACE -d 62.94.113.22 --dport 443 -j DNAT --to-destination 192.168.100.1:443
$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP
#
# Bad TCP packets we don't want
#
#
# Create separate chains for ICMP, TCP and UDP to traverse
#
$IPTABLES -N icmp_packets
$IPTABLES -N tcp_packets
$IPTABLES -N udpincoming_packets
#
# The allowed chain for TCP connections
#
$IPTABLES -N allowed
$IPTABLES -A allowed -p TCP --syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP
#
# ICMP rules
#
# Changed rules totally
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT
#
# TCP rules
#
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 21 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 22 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 80 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 113 -j allowed
#
# UDP ports
#
# nondocumented commenting out of these rules
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 53 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 123 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 2074 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 4000 -j ACCEPT
##########################
# FORWARD chain
#
# Accept the packets we actually want to forward
#
$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets
$IPTABLES -A FORWARD -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -p TCP -i $INET_IFACE -o $LAN_IFACE -d 192.168.100.1 --dport 80 -j allowed
$IPTABLES -A FORWARD -p TCP -i $INET_IFACE -o $LAN_IFACE -d 192.168.100.1 --dport 443 -j allowed
$IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT FORWARD packet died: "
##########################
# INPUT chain
#
# Bad TCP packets we don't want.
#
$IPTABLES -A INPUT -p tcp -j bad_tcp_packets
#
# Rules for incoming packets from the internet.
#
$IPTABLES -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets
$IPTABLES -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $INET_IFACE -j udpincoming_packets
#
# Rules for special networks not part of the Internet
#
$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -d $LAN_BCAST_ADRESS -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT INPUT packet died: "
###############################
# OUTPUT chain
#
#
# Bad TCP packets we don't want.
#
$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets
#
# Special OUTPUT rules to decide which IP's to allow.
#
$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $INET_IP -j ACCEPT
#
# Log weird packets that don't match the above.
#
$IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT OUTPUT packet died: "
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