iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
iptables –A INPUT –p icmp --icmp-type echo-reply –j ACCEPT
iptables –A OUTPUT –p icmp --icmp-type echo-request –j ACCEPT
iptables -A INPUT -i lo -p all -j ACCEPT
iptables –A OUTPUT –o lo –p all –j ACCEPT
iptables -A INPUT -p udp --sport 53 -j ACCEPT
iptables -A OUTPUT -p udp --sport 53 -j ACCEPT
原文:https://www.cnblogs.com/amoyzhu/p/9288117.html