#
   # 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"
 
   #
   # 1.1.1 DHCP
   #
 
   #
   # 1.1.2 PPPoE
   #
 
   #
   # 1.2 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 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.
   #
 
   LO_IFACE="lo"
   LO_IP="127.0.0.1"
 
   #
   # 1.5 IPTables Configuration.
   #
 
   IPTABLES="/usr/sbin/iptables"
 
   #
   # 1.6 Other Configuration.
   #
 
   ###########################################################################
   #
   # 2. Module loading.
   #
 
   #
   # Needed to initially load modules
   #
 
   /sbin/depmod -a
 
   #
   # 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.
   #
 
   #
   # 3.1 Required proc configuration
   #
 
   echo "1" > /proc/sys/net/ipv4/ip_forward
 
   #
   # 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
   #
 
   $IPTABLES -P INPUT DROP
   $IPTABLES -P OUTPUT DROP
   $IPTABLES -P FORWARD DROP
 
   #
   # 4.1.2 Create userspecified chains
   #
 
   #
   # Create chain for bad tcp packets
   #
 
   $IPTABLES -N bad_tcp_packets
 
   #
   # 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
 
   #
   # 4.1.3 Create content in userspecified chains
   #
 
   #
   # bad_tcp_packets chain
   #
 
   $IPTABLES -A bad_tcp_packets -p tcp –tcp-flags SYN,ACK SYN,ACK \
   –m state –state NEW -j REJECT –reject-with tcp-reset
   $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
 
   #
   # allowed chain
   #
 
   $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
 
   #
   # 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
   #
 
   #$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 53 -j ACCEPT
   #$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 123 -j ACCEPT
   $IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 2074 -j ACCEPT
   $IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 4000 -j ACCEPT
 
   #
   # In Microsoft Networks you will be swamped by broadcasts. These lines
   # will prevent them from showing up in the logs.
   #
 
   #$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d $INET_BROADCAST \
   #–destination-port 135:139 -j DROP
 
   #
   # If we get DHCP requests from the Outside of our network, our logs will
   # be swamped as well. This rule will block them from getting logged.
   #
 
   #$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d 255.255.255.255 \
   #–destination-port 67:68 -j DROP
 
   #
   # ICMP rules
   #
 
   $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
 
   #
   # 4.1.4 INPUT chain
   #
 
   #
   # Bad TCP packets we don't want.
   #
 
   $IPTABLES -A INPUT -p tcp -j bad_tcp_packets
 
   #
   # Rules for special networks not part of the Internet
   #
 
   $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
 
   #
   # Rules for incoming packets from anywhere.
   #
 
   $IPTABLES -A INPUT -p ALL -d $INET_IP -m state –state ESTABLISHED,RELATED \
   –j ACCEPT
   $IPTABLES -A INPUT -p TCP -j tcp_packets
   $IPTABLES -A INPUT -p UDP -j udp_packets
   $IPTABLES -A INPUT -p ICMP -j icmp_packets
 
   #
   # If you have a Microsoft Network on the outside of your firewall, you may
   # also get flooded by Multicasts. We drop them so we do not get flooded by
   # logs
   #
 
   #$IPTABLES -A INPUT -i $INET_IFACE -d 224.0.0.0/8 -j DROP
 
   #
   # Log weird packets that don't match the above.
   #
 
   $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
   #
 
   $IPTABLES -A FORWARD -p tcp -j bad_tcp_packets
 
   #
   # Accept the packets we actually want to forward
   #
 
   $IPTABLES -A FORWARD -p tcp –dport 21 -i $LAN_IFACE -j ACCEPT
   $IPTABLES -A FORWARD -p tcp –dport 80 -i $LAN_IFACE -j ACCEPT
   $IPTABLES -A FORWARD -p tcp –dport 110 -i $LAN_IFACE -j ACCEPT
   $IPTABLES -A FORWARD -m state –state ESTABLISHED,RELATED -j ACCEPT
 
   #
   # Log weird packets that don't match the above.
   #
 
   $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.
   #
 
   $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: "
 
   ######
   # 4.2 nat table
   #
 
   #
   # 4.2.1 Set policies
   #
 
   #
   # 4.2.2 Create user specified chains
   #
 
   #
   # 4.2.3 Create content in user specified chains
   #
 
   #
   # 4.2.4 PREROUTING chain
   #
 
   #
   # 4.2.5 POSTROUTING chain
   #
 
   #
   # Enable simple IP Forwarding and Network Address Translation
   #
 
   $IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT –to-source $INET_IP
 
   #
   # 4.2.6 OUTPUT chain
   #
 
   ######
   # 4.3 mangle table
   #
 
   #
   # 4.3.1 Set policies
   #
 
   #
   # 4.3.2 Create user specified chains
   #
 
   #
   # 4.3.3 Create content in user specified chains
   #
 
   #
   # 4.3.4 PREROUTING chain
   #
 
   #
   # 4.3.5 INPUT chain
   #
 
   #
   # 4.3.6 FORWARD chain
   #
 
   #
   # 4.3.7 OUTPUT chain
   #
 
   #
   # 4.3.8 POSTROUTING chain
   #

I.4. Пример rc.DHCP.firewall

   #!/bin/sh
   #
   # rc.firewall – DHCP IP 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_IFACE="eth0"
 
   #
   # 1.1.1 DHCP
   #
 
   #
   # Information pertaining to DHCP over the Internet, if needed.
   #
   # Set DHCP variable to no if you don't get IP from DHCP. If you get DHCP
   # over the Internet set this variable to yes, and set up the proper IP
   # address for the DHCP server in the DHCP_SERVER variable.
   #
 
   DHCP="no"
   DHCP_SERVER="195.22.90.65"
 
   #
   # 1.1.2 PPPoE
   #
 
   # Configuration options pertaining to PPPoE.
   #
   # If you have problem with your PPPoE connection, such as large mails not
   # getting through while small mail get through properly etc, you may set
   # this option to «yes» which may fix the problem. This option will set a
   # rule in the PREROUTING chain of the mangle table which will clamp
   # (resize) all routed packets to PMTU (Path Maximum Transmit Unit).
   #
   # Note that it is better to set this up in the PPPoE package itself, since
   # the PPPoE configuration option will give less overhead.
   #
 
   PPPOE_PMTU="no"
 
   #
   # 1.2 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 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.
   #
 
   LO_IFACE="lo"
   LO_IP="127.0.0.1"
 
   #
   # 1.5 IPTables Configuration.
   #
 
   IPTABLES="/usr/sbin/iptables"
 
   #
   # 1.6 Other Configuration.
   #
 
   ###########################################################################
   #
   # 2. Module loading.
   #
 
   #
   # Needed to initially load modules
   #
 
   /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.
   #
 
   #
   # 3.1 Required proc configuration
   #
 
   echo "1" > /proc/sys/net/ipv4/ip_forward
 
   #
   # 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
   #
 
   $IPTABLES -P INPUT DROP
   $IPTABLES -P OUTPUT DROP
   $IPTABLES -P FORWARD DROP
 
   #
   # 4.1.2 Create userspecified chains
   #
 
   #
   # Create chain for bad tcp packets
   #
 
   $IPTABLES -N bad_tcp_packets
 
   #
   # 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
 
   #
   # 4.1.3 Create content in userspecified chains
   #
 
   #
   # bad_tcp_packets chain
   #
 
   $IPTABLES -A bad_tcp_packets -p tcp –tcp-flags SYN,ACK SYN,ACK \
   –m state –state NEW -j REJECT –reject-with tcp-reset
   $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
 
   #
   # allowed chain
   #
 
   $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
 
   #
   # 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
   #
 
   $IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 53 -j ACCEPT
   if [ $DHCP == «yes» ] ; then
   $IPTABLES -A udp_packets -p UDP -s $DHCP_SERVER –sport 67 \
   –dport 68 -j ACCEPT
   fi
 
   #$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 53 -j ACCEPT
   #$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 123 -j ACCEPT
   $IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 2074 -j ACCEPT
   $IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 4000 -j ACCEPT
 
   #
   # In Microsoft Networks you will be swamped by broadcasts. These lines
   # will prevent them from showing up in the logs.
   #
 
   #$IPTABLES -A udp_packets -p UDP -i $INET_IFACE \
   #–destination-port 135:139 -j DROP
 
   #
   # If we get DHCP requests from the Outside of our network, our logs will
   # be swamped as well. This rule will block them from getting logged.
   #
 
   #$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d 255.255.255.255 \
   #–destination-port 67:68 -j DROP
 
   #
   # ICMP rules
   #
 
   $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
 
   #
   # 4.1.4 INPUT chain
   #
 
   #
   # Bad TCP packets we don't want.
   #
 
   $IPTABLES -A INPUT -p tcp -j bad_tcp_packets
 
   #
   # Rules for special networks not part of the Internet
   #
 
   $IPTABLES -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
   $IPTABLES -A INPUT -p ALL -i $LO_IFACE -j ACCEPT
 
   #
   # Special rule for DHCP requests from LAN, which are not caught properly
   # otherwise.
   #
 
   $IPTABLES -A INPUT -p UDP -i $LAN_IFACE –dport 67 –sport 68 -j ACCEPT
 
   #
   # Rules for incoming packets from the internet.
   #
 
   $IPTABLES -A INPUT -p ALL -i $INET_IFACE -m state –state ESTABLISHED,RELATED \
   –j ACCEPT
   $IPTABLES -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
   $IPTABLES -A INPUT -p UDP -i $INET_IFACE -j udp_packets
   $IPTABLES -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets
 
   #
   # If you have a Microsoft Network on the outside of your firewall, you may
   # also get flooded by Multicasts. We drop them so we do not get flooded by
   # logs
   #
 
   #$IPTABLES -A INPUT -i $INET_IFACE -d 224.0.0.0/8 -j DROP
 
   #
   # Log weird packets that don't match the above.
   #
 
   $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
   #
 
   $IPTABLES -A FORWARD -p tcp -j bad_tcp_packets
 
   #
   # Accept the packets we actually want to forward
   #
 
   $IPTABLES -A FORWARD -i $LAN_IFACE -j ACCEPT
   $IPTABLES -A FORWARD -m state –state ESTABLISHED,RELATED -j ACCEPT
 
   #
   # Log weird packets that don't match the above.
   #
 
   $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.
   #
 
   $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 -o $INET_IFACE -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: "
 
   ######
   # 4.2 nat table
   #
 
   #
   # 4.2.1 Set policies
   #
 
   #
   # 4.2.2 Create user specified chains
   #
 
   #
   # 4.2.3 Create content in user specified chains
   #
 
   #
   # 4.2.4 PREROUTING chain
   #
 
   #
   # 4.2.5 POSTROUTING chain
   #
 
   if [ $PPPOE_PMTU == «yes» ] ; then
   $IPTABLES -t nat -A POSTROUTING -p tcp –tcp-flags SYN,RST SYN \
   –j TCPMSS –clamp-mss-to-pmtu
   fi
   $IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE
 
   #
   # 4.2.6 OUTPUT chain
   #
 
   ######
   # 4.3 mangle table
   #
 
   #
   # 4.3.1 Set policies
   #
 
   #
   # 4.3.2 Create user specified chains
   #
 
   #
   # 4.3.3 Create content in user specified chains
   #
 
   #
   # 4.3.4 PREROUTING chain
   #
 
   #
   # 4.3.5 INPUT chain
   #
 
   #
   # 4.3.6 FORWARD chain
   #
 
   #
   # 4.3.7 OUTPUT chain
   #
 
   #
   # 4.3.8 POSTROUTING chain
   #

I.5. Пример rc.flush-iptables

   #!/bin/sh
   #
   # rc.flush-iptables – Resets iptables to default values.
   #
   # 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
 
   #
   # Configurations
   #
   IPTABLES="/usr/sbin/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
 
   #
   # reset the default policies in the mangle table.
   #
   $IPTABLES -t mangle -P PREROUTING ACCEPT
   $IPTABLES -t mangle -P OUTPUT ACCEPT
 
   #
   # flush all the rules in the filter and nat tables.
   #
   $IPTABLES -F
   $IPTABLES -t nat -F
   $IPTABLES -t mangle -F
   #
   # erase all chains that's not default in filter and nat table.
   #
   $IPTABLES -X
   $IPTABLES -t nat -X
   $IPTABLES -t mangle -X

I.6. Пример rc.test-iptables

   #!/bin/bash
   #
   # rc.test-iptables – test script for iptables chains and tables.
   #
   # 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
   #
 
   #
   # Filter table, all chains
   #
   iptables -t filter -A INPUT -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="filter INPUT:"
   iptables -t filter -A INPUT -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="filter INPUT:"
   iptables -t filter -A OUTPUT -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="filter OUTPUT:"
   iptables -t filter -A OUTPUT -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="filter OUTPUT:"
   iptables -t filter -A FORWARD -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="filter FORWARD:"
   iptables -t filter -A FORWARD -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="filter FORWARD:"
 
   #
   # NAT table, all chains except OUTPUT which don't work.
   #
   iptables -t nat -A PREROUTING -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="nat PREROUTING:"
   iptables -t nat -A PREROUTING -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="nat PREROUTING:"
   iptables -t nat -A POSTROUTING -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="nat POSTROUTING:"
   iptables -t nat -A POSTROUTING -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="nat POSTROUTING:"
   iptables -t nat -A OUTPUT -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="nat OUTPUT:"
   iptables -t nat -A OUTPUT -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="nat OUTPUT:"
 
   #
   # Mangle table, all chains
   #
   iptables -t mangle -A PREROUTING -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="mangle PREROUTING:"
   iptables -t mangle -A PREROUTING -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="mangle PREROUTING:"
   iptables -t mangle -I FORWARD 1 -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="mangle FORWARD:"
   iptables -t mangle -I FORWARD 1 -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="mangle FORWARD:"
   iptables -t mangle -I INPUT 1 -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="mangle INPUT:"
   iptables -t mangle -I INPUT 1 -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="mangle INPUT:"
   iptables -t mangle -A OUTPUT -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="mangle OUTPUT:"
   iptables -t mangle -A OUTPUT -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="mangle OUTPUT:"
   iptables -t mangle -I POSTROUTING 1 -p icmp –icmp-type echo-request \
   –j LOG –log-prefix="mangle POSTROUTING:"
   iptables -t mangle -I POSTROUTING 1 -p icmp –icmp-type echo-reply \
   –j LOG –log-prefix="mangle POSTROUTING:"