sudo iptables -L

 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

vim /etc/iptables.test.rules

然后输入

*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 REJECTCOMMIT

sudo iptables-restore < /etc/iptables.test.rules

vim /etc/network/if-pre-up.d/iptables

 #!/bin/sh sudo /sbin/iptables-restore < /etc/iptables.up.rules

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