ubuntu gufw防火墙阻塞已建立的连接

gufw默认的设置对已建立的连接，不起作用。只会阻塞新的连接。通过修改可以禁用新连接和旧连接。

/etc/ufw/before.rules

# allow all on loopback

-A ufw-before-input -i lo -j ACCEPT

-A ufw-before-output -o lo -j ACCEPT

# quickly process packets for which we already have a connection

#默认不阻塞关联和已建立的连接

#-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

#-A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

#-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

#改成这样也会阻塞已建立的连接

-A ufw-before-input -m conntrack --ctstate  -j ACCEPT

-A ufw-before-output -m conntrack --ctstate  -j ACCEPT

-A ufw-before-forward -m conntrack --ctstate  -j ACCEPT