Firewall на основе iptables



Выкладываю свою конфигурацию iptables. Надеюсь, что кому-нибудь пригодится...


#!/bin/sh

#
# rc.firewall - Initial SIMPLE IP Firewall script for Linux 2.4.x and iptables
#

###########################################################################
#
# 1. Configuration options.
#

#
# 1.1 Internet Configuration.
#

INET_IP="80.255.178.61"
INET_IFACE="ppp0"
INET_BROADCAST="80.255.191.255"

#
# 1.1.1 DHCP
#

#
# 1.1.2 PPPoE
#

#
# 1.2 Local Area Network configuration.
#

LAN_IP="192.168.0.1"
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="/sbin/iptables"

#
# 1.6 Other Configuration.
#

LANTT_IP="10.32.208.7"
LANTT_IFACE="eth0"
LANTT_BROADCAST="10.32.255.255"

###########################################################################
#
# 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
#

#FIXME Must be in the end
echo "0" > /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
#

###########
## nmap -sS (Scan: SYN+ACK = no defense... )
## nmap -sX (Scan: SYN+ACK+FIN+RST [+PSH+URG] = not implemented in TCP)
$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST ALL \
-j LOG --log-level DEBUG --log-prefix "IPT TCP Scan: S+A+F+R: "

$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST ALL \
-j REJECT --reject-with tcp-reset

## nmap -sN (Scan: none of any flags = not implemented in TCP)
$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST NONE \
-m limit --limit 10/minute --limit-burst 10 \
-j LOG --log-level DEBUG --log-prefix "IPT TCP Scan: empty flags: "
$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST NONE \
-j REJECT --reject-with tcp-reset

## nmap -sF (Scan: only FIN)
$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST FIN \
-m limit --limit 10/minute --limit-burst 10 \
-j LOG --log-level DEBUG --log-prefix "IPT TCP Scan: only FIN: "
$IPTABLES -t filter -A bad_tcp_packets -p tcp -m state ! --state ESTABLISHED \
--tcp-flags SYN,ACK,FIN,RST FIN \
-j REJECT --reject-with tcp-reset

## NEW, not SYN
$IPTABLES -t filter -A bad_tcp_packets -p tcp --syn -m state ! --state NEW \
-m limit --limit 10/minute --limit-burst 10 \
-j LOG --log-level DEBUG --log-prefix "IPT TCP Scan: NEW not SYN: "
$IPTABLES -t filter -A bad_tcp_packets -p tcp --syn -m state ! --state NEW \
-j REJECT --reject-with tcp-reset
###########

#SIMPLE ANTI-SCAN
#
#$IPTABLES -A bad_tcp_packets -p tcp --tcp-flags SYN,ACK SYN,ACK \
#-m state --state NEW -j LOG --log-level DEBUG \
#--log-prefix "IPT BAD_TCP died:SCAN "
#$IPTABLES -A bad_tcp_packets -p tcp --tcp-flags SYN,ACK SYN,ACK \
#-m state --state NEW -j REJECT --reject-with tcp-reset
#
#$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \
#--log-level DEBUG --log-prefix "IPT BAD_TCP died:SCAN "
#$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j REJECT \
#--reject-with tcp-reset

#
# 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 LOG --log-level DEBUG \
--log-prefix "IPT ALLOWED died:NOT MATCH "
$IPTABLES -A allowed -p TCP -j REJECT --reject-with tcp-reset

#
# 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
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 1723 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 6881 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 10.0.0.0/8 --dport 3128 -j allowed

#
# UDP ports
#

#$IPTABLES -A udp_packets -p UDP -s 0/0 --dport 53 -j ACCEPT
#$IPTABLES -A udp_packets -p UDP -s 0/0 --dport 123 -j ACCEPT
#$IPTABLES -A udp_packets -p UDP -s 0/0 --dport 2074 -j ACCEPT
#$IPTABLES -A udp_packets -p UDP -s 0/0 --dport 4000 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --dport 6881 -j ACCEPT


#
# Block all broadcasts
#

$IPTABLES -A udp_packets -p ALL -i $INET_IFACE -d 255.255.255.255 \
-j LOG --log-level DEBUG --log-prefix "IPT UDP died:BCAST "
$IPTABLES -A udp_packets -p ALL -i $INET_IFACE -d 255.255.255.255 \
-j DROP

$IPTABLES -A udp_packets -p ALL -i $LANTT_IFACE -d 255.255.255.255 \
-j LOG --log-level DEBUG --log-prefix "IPT UDP died:BCAST "
$IPTABLES -A udp_packets -p ALL -i $LANTT_IFACE -d 255.255.255.255 \
-j DROP

#
# 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 \
--dport 135:139 -j LOG --log-level DEBUG --log-prefix "IPT UDP died:MS BCAST "
$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d $INET_BROADCAST \
--dport 135:139 -j DROP

$IPTABLES -A udp_packets -p UDP -i $LANTT_IFACE -d $LANTT_BROADCAST \
--dport 135:139 -j LOG --log-level DEBUG --log-prefix "IPT UDP died:MS BCAST "
$IPTABLES -A udp_packets -p UDP -i $LANTT_IFACE -d $LANTT_BROADCAST \
--dport 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 \
--dport 67:68 -j LOG --log-level DEBUG --log-prefix "IPT UDP died:DHCP "
$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d 255.255.255.255 \
--dport 67:68 -j DROP

$IPTABLES -A udp_packets -p UDP -i $LANTT_IFACE -d 255.255.255.255 \
--dport 67:68 -j LOG --log-level DEBUG --log-prefix "IPT UDP died:DHCP "
$IPTABLES -A udp_packets -p UDP -i $LANTT_IFACE -d 255.255.255.255 \
--dport 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 -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

#
# 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 -d $INET_IP -m state --state ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A INPUT -p ALL -d $LANTT_IP -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

$IPTABLES -A INPUT -p TCP -i $LANTT_IFACE -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $LANTT_IFACE -j udp_packets
$IPTABLES -A INPUT -p ICMP -i $LANTT_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 LOG --log-level DEBUG \
--log-prefix "IPT INPUT died:MCAST "
$IPTABLES -A INPUT -i $INET_IFACE -d 224.0.0.0/8 -j DROP

$IPTABLES -A INPUT -i $LANTT_IFACE -d 224.0.0.0/8 -j LOG --log-level DEBUG \
--log-prefix "IPT INPUT died:MCAST "
$IPTABLES -A INPUT -i $LANTT_IFACE -d 224.0.0.0/8 -j DROP

#
# Log weird packets that don't match the above.
#

$IPTABLES -A INPUT -j LOG \
--log-level DEBUG --log-prefix "IPT INPUT died:NOT MATCH "

#
# 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 died: NO MATCH"

#
# 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 $LANTT_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 -j LOG --log-level DEBUG \
--log-prefix "IPT OUTPUT died:NOT MATCH "

######
# 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
#

Использованные источники: opennnet.ru linux.org.ru
5
14 Апреля 2010, 15:36
2
2324

Комментарии

Очень полезно будет ограничить кол-во соединений с SSH в минуту, чтобы предотвратить brute force атаку
  
  $IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 22 -m state --syn --state NEW
  -m limit --limit 1/minute --limit-burst 2 -j allowed
  $IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 22 -m state --syn --state NEW
  -j REJECT --reject-with tcp-reset
  
15 Апреля 2010, 14:49 цитировать

0
Илья Андреевич
спасибо
08 Июля 2010, 11:29 цитировать

+1

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