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Debian默认已经安装iptables，查看规则iptables -L默认允许所有出入，这是非常不安全的，因此需要对规则进行调整。
编辑配置文件：
/etc/iptables.test.rules
添加下面的规则，请根据实际情况调整：
*filter # Allows all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0 -A INPUT -i lo -j ACCEPT -A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT # Accepts all established inbound connections -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # Allows all outbound traffic # You could modify this to only allow certain traffic -A OUTPUT -j ACCEPT # Allows HTTP and HTTPS connections from anywhere (the normal ports for websites) -A INPUT -p tcp --dport 80 -j ACCEPT -A INPUT -p tcp --dport 443 -j ACCEPT # Allows SSH connections # The --dport number is the same as in /etc/ssh/sshd_config -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT # Now you should read up on iptables rules and consider whether ssh access # for everyone is really desired. Most likely you will only allow access from certain IPs. # Allow ping # note that blocking other types of icmp packets is considered a bad idea by some # remove -m icmp --icmp-type 8 from this line to allow all kinds of icmp: # https://security.stackexchange.com/questions/22711 -A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT # log iptables denied calls (access via 'dmesg' command) -A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7 # Reject all other inbound - default deny unless explicitly allowed policy: -A INPUT -j REJECT -A FORWARD -j REJECT COMMIT
激活规则：
iptables-restore < /etc/iptables.test.rules
保存规则到主配置文件：
iptables-save > /etc/iptables.up.rules
开机自动加载规则
#编辑配置 /etc/network/if-pre-up.d/iptables
添加如下内容
#!/bin/sh /sbin/iptables-restore < /etc/iptables.up.rules
添加执行权限
chmod +x /etc/network/if-pre-up.d/iptables
OK,一切皆已搞定，感觉比CentOS的iptables要麻烦一点。
允许某段IP访问本机的所有类型的所有端口
sudo iptables -I INPUT -s 192.168.2.0/24 -p all -j ACCEPT sudo iptables -I INPUT -s 192.168.0.0/16 -p all -j ACCEPT
查看iptables规则，以数字形式
sudo iptables -L -n
查看iptables规则的序号，用于删除规则参考
sudo iptables -L -n --line-numbers
清除单条iptables规则
sudo iptables -D INPUT(链) 3(规则对应的序号)
允许已经建立的连接发送和接收数据，以免设置链为DROP时远程ssh断开
sudo iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
允许本机127.0.0.1访问自身所有端口
sudo iptables -I INPUT -s 127.0.0.1 -p all -j ACCEPT
正文完
