#!/bin/sh # # rc.firewall - Initial SIMPLE 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 # # # modifications de P. Petit # l'original peut être trouvé là : https://inetdoc.net/guides/iptables-tutorial/examplecode.html#includercfirewall # # options de debug du shell # #set -e #set -x set -u ########################################################################### # # 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 on dsactive le routage echo "0" > /proc/sys/net/ipv4/ip_forward # protection contre une partie du spoofing echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter # # # on remet tout à zéro (table filter et nat) # $IPTABLES --flush $IPTABLES --delete-chain $IPTABLES --table nat --flush $IPTABLES --table nat --delete-chain ########################################################################### # # 4. rules set up. # ###### # 4.1 Filter table # # # 4.1.1 Set policies # # politique par défaut et activitation du suivi de connexion sur toutes les chaines de la table filter for ch in INPUT OUTPUT DROP do $IPTABLES -P $ch DROP $IPTABLES -A $ch -m state --state ESTABLISHED,RELATED -j ACCEPT done ################################################################################ # # 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 -j DROP # # TCP rules # # à remplacer par les votres # $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 $IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 113 -j allowed # # UDP ports # # à remplacer par les votres # #$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 53 -j ACCEPT #$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 123 -j ACCEPT #$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 2074 -j ACCEPT #$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 4000 -j ACCEPT # # ICMP rules # # note: jeu de règle incomplet à completer par au moins les icmp frag needed $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 -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 the internet. # # règles à remplacer par les votres # $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 # # 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 # # règle à remplacer par les votres # # $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 -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: " ################################################################################ # # on active le routage # echo "1" > /proc/sys/net/ipv4/ip_forward