shell脚本实例：iptables防护脚本

#echo "Starting kerryhu-iptables rules..."
#!/bin/bash

IPT="/sbin/iptables"
CONNECTION_TRACKING="1"
CLASS_A="10.0.0.0/8"
CLASS_B="172.16.0.0/12"
CLASS_C="192.168.0.0/16"
CLASS_D_MULTICAST="224.0.0.0/4"
CLASS_E_RESERVED_NET="240.0.0.0/5"
BROADCAST_SRC="0.0.0.0"
BROADCAST_DEST="255.255.255.255"
LOOPBACK_INTERFACE="lo"
#Remove any existing rules
$IPT -F
$IPT -X
#setting default firewall policy
$IPT -P FORWARD DROP
$IPT -P INPUT DROP
$IPT -P OUTPUT DROP

#setting for loopback interface
$IPT -A INPUT -i lo -j ACCEPT
$IPT -A OUTPUT -o lo -j ACCEPT

# Stealth Scans and TCP State Flags
# All of the bits are cleared
$IPT -A INPUT -p tcp --tcp-flags ALL NONE -j DROP
# SYN and FIN are both set
$IPT -A INPUT -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
# SYN and RST are both set
$IPT -A INPUT -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
# FIN and RST are both set
$IPT -A INPUT -p tcp --tcp-flags FIN,RST FIN,RST -j DROP
# FIN is the only bit set, without the expected accompanying ACK
$IPT -A INPUT -p tcp --tcp-flags ACK,FIN FIN -j DROP
# PSH is the only bit set, without the expected accompanying ACK
$IPT -A INPUT -p tcp --tcp-flags ACK,PSH PSH -j DROP
# URG is the only bit set, without the expected accompanying ACK
$IPT -A INPUT -p tcp --tcp-flags ACK,URG URG -j DROP

# Using Connection State to By-pass Rule Checking
if [ "$CONNECTION_TRACKING" = "1" ]; then
    $IPT -A INPUT  -m state --state ESTABLISHED,RELATED -j ACCEPT
    $IPT -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
    $IPT -A INPUT -m state --state INVALID -j DROP
    $IPT -A OUTPUT -m state --state INVALID -j DROP
fi
#-----------------#
# Source Address Spoofing and Other Bad Addresses
# Refuse spoofed packets pretending to be from
# the external interface.s IP address
# Refuse packets claiming to be from a Class A private network
$IPT -A INPUT -s $CLASS_A -j DROP
# Refuse packets claiming to be from a Class B private network
$IPT -A INPUT -s $CLASS_B -j DROP
# Refuse packets claiming to be from a Class C private network
$IPT -A INPUT -s $CLASS_C -j DROP
$IPT -A INPUT -s 0.0.0.0/8 -j DROP
$IPT -A INPUT -s 169.254.0.0/16 -j DROP
$IPT -A INPUT -s 192.0.2.0/24 -j DROP
#-----------------#
#setting access rules
#允许出站域名解析
$IPT -A OUTPUT -p udp  --dport 53 -j ACCEPT
#$IPT -A OUTPUT -p tcp  -d 61.177.7.1 --dport 53 -j ACCEPT
#$IPT -A OUTPUT -p udp  -d 61.177.7.1 --dport 53 -j ACCEPT
#时钟同步
$IPT -A OUTPUT -d 192.43.244.18 -j ACCEPT
#$IPT -A OUTPUT -p udp -d 192.43.244.18 --dport 123 -j ACCEPT
#允许ping出
$IPT -A OUTPUT -p icmp -j ACCEPT
#允许ftp备份
#$IPT -A OUTPUT -p tcp -d 222.102.153.191 --dport 21 -j ACCEPT
#$IPT -A OUTPUT -p tcp -d 222.102.153.191 --dport 20 -j ACCEPT
$IPT -A OUTPUT -d 222.102.153.191 -j ACCEPT
#允许出站http
$IPT -A OUTPUT -p tcp  --dport 80 -j ACCEPT
#允许yum更新
$IPT -A OUTPUT -p tcp -d mirrors.163.com -j ACCEPT
#允许入站ssh
$IPT -A INPUT -p tcp -s 58.102.13.91 --dport 22 -j ACCEPT
#允许cacti监控
#$IPT -A INPUT -p tcp -s 222.102.153.192 --dport 161 -j ACCEPT
$IPT -A INPUT -s 222.102.153.192 -j ACCEPT
#$IPT -A INPUT -p tcp  --dport 443 -j ACCEPT
#$IPT -A INPUT -p tcp  --dport 80 -j ACCEPT
#$IPT -A INPUT -p tcp -s 127.0.0.1 --dport 3306 -j ACCEPT