Ubuntu 14.04 配置iptables防火墙

# whereis iptables

#查看系统是否安装防火墙可以看到:

iptables: /sbin/iptables /usr/share/iptables /usr/share/man/man8/iptables.8.gz #表示已经安装iptables
apt-get install iptables #如果默认没有安装，请运行此命令安装防火墙

# iptables -L

#查看防火墙配置信息，显示如下:

Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination

# vi /etc/iptables.rules

添加以下内容(备注:80是指web服务器端口,3306是指MySQL数据库链接端口,22是指SSH远程管理端口.)

*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:syn-flood - [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT
-A INPUT -p icmp -m limit --limit 100/sec --limit-burst 100 -j ACCEPT
-A INPUT -p icmp -m limit --limit 1/s --limit-burst 10 -j ACCEPT
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j syn-flood
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A syn-flood -p tcp -m limit --limit 3/sec --limit-burst 6 -j RETURN
-A syn-flood -j REJECT --reject-with icmp-port-unreachable
COMMIT

# iptables-restore < /etc/iptables.rules

#使防火墙规则生效

# vi /etc/network/if-pre-up.d/iptables

#创建文件，添加以下内容，使防火墙开机启动

#!/bin/bash
iptables-restore < /etc/iptables.rules

# chmod +x /etc/network/if-pre-up.d/iptables

#添加执行权限

# iptables -L -n

查看规则是否生效.