适合Web服务器的iptables规则

#! /bin/sh
# /etc/iptables.bak

# Let's save typing & confusion with variables
IPTABLES=/sbin/iptables

# Flush active rules and custom tables
$IPTABLES --flush
$IPTABLES --delete-chain

# set the defaults so that by-default incoming packets are dropped, unless explicitly allowed;
# for a desktop workstation, we'll let lots of (unpredictable) outgoing packets go freely.
$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT ACCEPT

# INBOUND POLICY
# ==============
# of course, accepting loopback is a good idea
$IPTABLES -A INPUT -i lo -j ACCEPT

# we will permit ping, but rate-limit type 8 to prevent DoS-attack
$IPTABLES -A INPUT -p icmp --icmp-type 0 -j ACCEPT
$IPTABLES -A INPUT -p icmp --icmp-type 3 -j ACCEPT
$IPTABLES -A INPUT -p icmp --icmp-type 11 -j ACCEPT
$IPTABLES -A INPUT -p icmp --icmp-type 8 -m limit --limit 1/second -j ACCEPT

#   (Applies to packets entering our network interface from the network,
#   and addressed to this host.)

$IPTABLES -A INPUT -m state --state INVALID -j DROP
$IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# ftp incoming
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 20 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 21 -j ACCEPT

# ssh incoming, including non-standard port (if needed)
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT
#$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 222 -j ACCEPT

# web serving, let's allow it!
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 80 -j ACCEPT

# secure web serving, let's allow it!
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 443 -j ACCEPT

# amanda tape-backups; we reach out and tape things from this machine
$IPTABLES -A INPUT -p udp -m state --state NEW -m udp --dport 10080 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 10082 -j ACCEPT
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 10083 -j ACCEPT

# nagios (5666); monitor time (123), allow snmp (161)
$IPTABLES -A INPUT -p tcp -m state --state NEW --dport 5666 -j ACCEPT
$IPTABLES -A INPUT -p udp -m udp --dport 123 -j ACCEPT
$IPTABLES -A INPUT -p udp -m udp --dport 161 -j ACCEPT


# OUTBOUND POLICY
# ===============
# of course, accepting loopback is a good idea
$IPTABLES -A OUTPUT -o lo -j ACCEPT

#   (Applies to packets sent to the network interface from local processes)

$IPTABLES -A OUTPUT -j ACCEPT
根据自己的服务器的具体环境作适当修改，然后把上面的代码保存到/etc/iptables.bak。
运行脚本：
sh /etc/iptables.bak
查看规则：
iptables -L
保存规则：
service iptables save