用Linux+Iptables构建防火墙实例

核心提示： [root@jiaoyuang init.d]# ./iptables saveSaving current rules to /etc/sysconfig/iptables: [ OK ][root@jiaoyuang init.d]# cat /etc/sysconfig/iptabl

[root@jiaoyuang init.d]# ./iptables saveSaving current rules to /etc/sysconfig/iptables: [ OK ][root@jiaoyuang init.d]# cat /etc/sysconfig/iptables

# Generated by iptables-save v1.2.4 on Sat Sep 28 16:51:22 2002

*mangle

:PREROUTING ACCEPT [61522:8074850]

:OUTPUT ACCEPT [1079:79301]

COMMIT

# Completed on Sat Sep 28 16:51:22 2002

# Generated by iptables-save v1.2.4 on Sat Sep 28 16:51:22 2002

*nat

:PREROUTING ACCEPT [31850:5091703]

:POSTROUTING ACCEPT [20:1240]

:OUTPUT ACCEPT [12:776]

COMMIT

# Completed on Sat Sep 28 16:51:22 2002

# Generated by iptables-save v1.2.4 on Sat Sep 28 16:51:22 2002

*filter

:INPUT ACCEPT [61444:8070296]

:FORWARD ACCEPT [34:1984]

:OUTPUT ACCEPT [1079:79301]

COMMIT

安装并启动IPTABLES

在安装RedHat Linux V7.3后，iptables就已经被安装了，但默认启动的是ipchains。你在安装时所定义的一些规则也在/etc/sysconfig/ipchains中被定义。我们需要将其停止，才能启动iptables(注意：虽然不停止ipchains也可以启动iptables，但这时iptables并没有真正的起作用。Ipchains和iptables是两个防火墙，你只能选择一个)。

service ipchains stop (停止ipchains)

chkconfig --level 2345 ipchains off (使ipchains系统启动时不自动启动)

chkconfig --level 2345 iptables on (使iptables 在系统启动时自动启动)

vi /etc/rc.d/rc.local (编辑rc.local，将下面四行加到最后)