上手Linux底层iptables 防火墙 保障Linux安全

Debian/Ubuntu

了解系统初始防火墙情况

iptables -L

卸载之前的防火墙

apt purge -y ufw

apt purge -y iptables-persistent

安装iptables-persistent

apt update -y && apt install -y iptables-persistent nano

编辑文件

nano /etc/iptables/rules.v4

编辑的内容

*filter 

:INPUT DROP [0:0] 

:FORWARD DROP [0:0] 

:OUTPUT ACCEPT [0:0] 

-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 

-A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 

-A INPUT -p tcp --dport 22 -j ACCEPT

-A INPUT -i lo -j ACCEPT

-A FORWARD -i lo -j ACCEPT

COMMIT

加载规则

iptables-restore < /etc/iptables/rules.v4

systemctl enable netfilter-persistent

systemctl restart netfilter-persistent

查看链与规则

iptables -L

CentOS

了解系统初始防火墙情况

iptables -L

卸载上层防火墙

yum remove -y firewalld

安装

yum update -y && yum install -y iptables-services

启动

systemctl enable iptables

systemctl start iptables

清除已有规则

iptables -F

添加规则

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

iptables -A INPUT -i lo -j ACCEPT

iptables -A FORWARD -i lo -j ACCEPT

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 

iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -P INPUT DROP

iptables -P FORWARD DROP

保存开机生效

service iptables save

systemctl restart iptables

查看链与规则

iptables -L