Iptables Tutorial 1.1.19

Andreasson Oskar

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$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT –to-source $INET_IP

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# 4.2.6 OUTPUT chain

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######

# 4.3 mangle table

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# 4.3.1 Set policies

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# 4.3.2 Create user specified chains

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# 4.3.3 Create content in user specified chains

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# 4.3.4 PREROUTING chain

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# 4.3.5 INPUT chain

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# 4.3.6 FORWARD chain

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# 4.3.7 OUTPUT chain

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# 4.3.8 POSTROUTING chain

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I.3.

Пример rc.UTIN.firewall

#!/bin/sh

#

# rc.firewall – UTIN Firewall script for Linux 2.4.x and iptables

#

# Copyright (C) 2001 Oskar Andreasson <bluefluxATkoffeinDOTnet>

#

# 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.

#

#

# 1.1 Internet Configuration.

#

INET_IP="194.236.50.155"

INET_IFACE="eth0"

INET_BROADCAST="194.236.50.255"

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# 1.1.1 DHCP

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#

# 1.1.2 PPPoE

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#

# 1.2 Local Area Network configuration.

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# your LAN's IP range and localhost IP. /24 means to only use the first 24

# bits of the 32 bit IP address. the same as netmask 255.255.255.0

#

LAN_IP="192.168.0.2"

LAN_IP_RANGE="192.168.0.0/16"

LAN_IFACE="eth1"

#

# 1.3 DMZ Configuration.

#

#

# 1.4 Localhost Configuration.

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LO_IFACE="lo"

LO_IP="127.0.0.1"

#

# 1.5 IPTables Configuration.

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IPTABLES="/usr/sbin/iptables"

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# 1.6 Other Configuration.

#

###########################################################################

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# 2. Module loading.

#

#

# Needed to initially load modules

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/sbin/depmod -a

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# 2.1 Required modules

#

/sbin/modprobe ip_tables

/sbin/modprobe ip_conntrack

/sbin/modprobe iptable_filter

/sbin/modprobe iptable_mangle

/sbin/modprobe iptable_nat

/sbin/modprobe ipt_LOG

/sbin/modprobe ipt_limit

/sbin/modprobe ipt_state

#

# 2.2 Non-Required modules

#

#/sbin/modprobe ipt_owner

#/sbin/modprobe ipt_REJECT

#/sbin/modprobe ipt_MASQUERADE

#/sbin/modprobe ip_conntrack_ftp

#/sbin/modprobe ip_conntrack_irc

#/sbin/modprobe ip_nat_ftp

#/sbin/modprobe ip_nat_irc

###########################################################################

#

# 3. /proc set up.

#

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# 3.1 Required proc configuration

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echo "1" > /proc/sys/net/ipv4/ip_forward

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# 3.2 Non-Required proc configuration

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#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

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$IPTABLES -P INPUT DROP

$IPTABLES -P OUTPUT DROP

$IPTABLES -P FORWARD DROP

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# 4.1.2 Create userspecified chains

#

#

# Create chain for bad tcp packets

#

$IPTABLES -N bad_tcp_packets

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

#

$IPTABLES -N allowed

$IPTABLES -N tcp_packets

$IPTABLES -N udp_packets

$IPTABLES -N icmp_packets

#