#!/bin/sh # # rc.firewall - Initial SIMPLE IP Firewall test script for 2.4.x # # Author: Oskar Andreasson # (c) of BoingWorld.com, use at your own risk, do whatever you please with # it as long as you don't distribute this with due credits to # BoingWorld.com # ########### # Configuration options, these will speed you up getting this script to # work with your own setup. # # 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 # # STATIC_IP is used by me to allow myself to do anything to myself, might # be a security risc but sometimes I want this. If you don't have a static # IP, I suggest not using this option at all for now but it's still # enabled per default and will add some really nifty security bugs for all # those who skips reading the documentation=) LAN_IP_RANGE="10.0.0.0/24" LAN_IP="10.0.0.1/32" LAN_BCAST_ADRESS="10.0.0.255/32" LOCALHOST_IP="127.0.0.1/32" #STATIC_IP="194.236.50.155/32" INET_IFACE="eth2" LAN_IFACE="eth0" WEB_IFACE="eth1" IPTABLES="/sbin/iptables" # Reset all previous chains $IPTABLES -F $IPTABLES -X ######### # Load all required IPTables modules # # # Needed to initially load modules # /sbin/depmod -a # # Adds some iptables targets like LOG, REJECT and MASQUARADE. # /sbin/modprobe ipt_LOG /sbin/modprobe ipt_REJECT /sbin/modprobe ipt_MASQUERADE # # Support for owner matching # #/sbin/modprobe ipt_owner # Support for FTP connection - PORT COMMAND # loadable module /sbin/modprobe ip_nat_ftp # # Support for connection tracking of FTP and IRC. # /sbin/modprobe ip_conntrack_ftp #/sbin/modprobe ip_conntrack_irc #CRITICAL: Enable IP forwarding since it is disabled by default. # echo "1" > /proc/sys/net/ipv4/ip_forward # Dynamic IP users: # # If you get your IP address dynamically from SLIP, PPP, or DHCP, enable this # option. This enables dynamic-ip address hacking in IP MASQ, making the connection # with Diald and similar programs much easier. # #echo "1" > /proc/sys/net/ipv4/ip_dynaddr # Enable simple IP FORWARDing and Masquerading # # NOTE: The following is an example for an internal LAN, where the lan # runs on eth1, and the Internet is on eth0. # # Please change the network devices to match your own configuration. # $IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE $IPTABLES -A FORWARD -i $LAN_IFACE -j ACCEPT $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: " # # set default policies for the INPUT, FORWARD and OUTPUT chains # $IPTABLES -P INPUT ACCEPT $IPTABLES -P OUTPUT ACCEPT $IPTABLES -P FORWARD DROP # # 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 # # This chain will be utilised if someone tries to connect to an allowed # port from the internet. If they are opening the connection, or if it's # already established we ACCEPT the packages, if not we fuck them. This is # where the state matching is performed also, we allow ESTABLISHED and # RELATED packets. $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 # $IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 0 -j ACCEPT $IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 3 -j ACCEPT $IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 5 -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 # $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 $IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 4000 -j ACCEPT # # PREROUTING chain. # # Do some checks for obviously spoofed IP's # #$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 192.168.0.0/16 -j DROP $IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 10.0.0.0/24 -j DROP #$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 172.16.0.0/12 -j DROP # # INPUT chain # # establish the basic INPUT chain and filter the packets onto the correct # chains. # $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 $IPTABLES -A INPUT -p ALL -i $LAN_IFACE -d $LAN_BCAST_ADRESS -j ACCEPT $IPTABLES -A INPUT -p ALL -d $LOCALHOST_IP -j ACCEPT $IPTABLES -A INPUT -p ALL -d $LAN_IP -j ACCEPT $IPTABLES -A INPUT -p ALL -d $STATIC_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 # # establish the basic OUTPUT chain and filter them onto the correct chain # $IPTABLES -A OUTPUT -p ALL -s $LOCALHOST_IP -j ACCEPT $IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT #$IPTABLES -A OUTPUT -p ALL -s $STATIC_IP -j ACCEPT $IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG --log-level DEBUG --log-prefix "IPT OUTPUT packet died: " # USER DEFINED CHAINS $IPTABLES -A INPUT -s 10.0.0.0/24 -j ACCEPT $IPTABLES -A INPUT -s 212.5.209.233/32 -j DROP -d any/0 $IPTABLES -A INPUT -s 216.160.43.201/32 -j DROP -d any/0 $IPTABLES -A FORWARD -p TCP --dport 21 -d 212.55.235.58/32 -j ACCEPT $IPTABLES -A FORWARD -p TCP --dport 80 -d 212.55.235.58/32 -j ACCEPT $IPTABLES -A FORWARD -s 10.0.0.50/32 -d 212.55.235.58/32 -j ACCEPT $IPTABLES -A FORWARD -p TCP --dport 4661 -d 195.168.26.137 -j ACCEPT $IPTABLES -A FORWARD -p TCP --dport 4662 -d 195.168.26.137 -j ACCEPT $IPTABLES -A FORWARD -p TCP --sport 4661 -s 195.168.26.137 -j ACCEPT $IPTABLES -A FORWARD -p TCP --sport 4662 -s 195.168.26.137 -j ACCEPT $IPTABLES -A FORWARD -p UDP --dport 4665 -d 195.168.26.137 -j ACCEPT $IPTABLES -A FORWARD -p UDP --sport 4665 -s 195.168.26.137 -j ACCEPT # Mandrake-Security : if you remove this comment, remove the next line too. #echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter