iptables 和 google recaptcha 的问题

Question

我正在运行一个装有 Ubuntu 20.04 的云服务器，它托管着一个论坛。该论坛使用 Google 的 reCaptcha 来保护新注册。

但是，当我设置好 iptable 规则后，reCaptcha 就会超时。如果我禁用规则，一切就都好了。

我不是这方面的专家，现有的规则主要来自强化指南（1，2）这就是我所拥有的：

Chain INPUT (policy DROP)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             multiport dports 22,http,https,submission state NEW,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere             icmp echo-reply
ACCEPT     icmp --  anywhere             anywhere             icmp echo-request
ACCEPT     all  --  anywhere             anywhere
ACCEPT     udp  --  anywhere             anywhere             udp spt:domain
DROP       all  -f  anywhere             anywhere
DROP       all  -f  anywhere             anywhere
DROP       tcp  --  anywhere             anywhere             tcp flags:!FIN,SYN,RST,ACK/SYN state NEW
DROP       tcp  --  anywhere             anywhere             tcp flags:FIN,SYN,RST,PSH,ACK,URG/FIN,SYN,RST,PSH,ACK,URG

Chain FORWARD (policy DROP)
target     prot opt source               destination

Chain OUTPUT (policy DROP)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             anywhere             multiport sports 22,http,https,submission state ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere             icmp echo-request
ACCEPT     icmp --  anywhere             anywhere             icmp echo-reply
ACCEPT     all  --  anywhere             anywhere
ACCEPT     udp  --  anywhere             anywhere             udp dpt:domain

因此，如果我将链默认策略更改为 ACCEPT，则一切正常，因此错误一定出在上述规则之一中。但是，HTTP/HTTPS 肯定已启用，并且搜索其他端口后找不到 reCaptcha 使用的更多端口。

有人能帮助我让它工作吗？