#!/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
      #

      #!/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

      #!/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:"