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 #
