当Docker在主机上运行时，Iptables规则是notoriously difficult设置的，我认为我在这篇精彩的博文中有一个明确的解决方案：https://unrouted.io/2017/08/15/docker-firewall/
这篇博客文章中描述的配置很长时间以来一直很好用，但我现在面临着一个前所未有的问题。
我正在运行一个docker容器，它在主机上的端口465上公开服务。端口465映射到容器中的端口25。以下是模拟此类服务的方法：
$ docker run --rm -it -p 465:25 python:3.6 python3 -m http.server 25
我的问题是我无法从外部访问服务器上的端口465：
$ curl mydomain.com:465
curl: (7) Failed to connect to mydomain.com port 465: No route to host
然而，这是有趣的部分，如果主机上的端口映射到容器中的同一端口，我确实设法访问该服务。换句话说，当我在主机上运行时：
$ docker run --rm -it -p 465:465 python:3.6 python3 -m http.server 465
然后我可以从外面访问服务：
$ curl mydomain.com:465
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org...
整个问题是由于我的iptables定义：我知道，因为当我刷新iptables规则时，无论端口映射如何，我都设法从外部访问服务。
这是我的iptable规则：
*filter
# Source: https://unrouted.io/2017/08/15/docker-firewall/
:INPUT ACCEPT [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:FILTERS - [0:0]
:DOCKER-USER - [0:0]
-F INPUT
-F DOCKER-USER
-F FILTERS
-A INPUT -i lo -j ACCEPT
-A INPUT ! -i lo -s 127.0.0.0/8 -j REJECT
-A INPUT -p icmp --icmp-type any -j ACCEPT
-A INPUT -j FILTERS
-A DOCKER-USER -i eth0 -j FILTERS
-A FILTERS -m state --state ESTABLISHED,RELATED -j ACCEPT
-A FILTERS -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A FILTERS -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A FILTERS -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
-A FILTERS -m state --state NEW -m tcp -p tcp --dport 465 -j ACCEPT
-A FILTERS -j REJECT --reject-with icmp-host-prohibited
COMMIT
我应该如何修改我的iptables，以便我可以从外部访问我的容器，无论端口映射是什么？
编辑：
以下是失败方案（465:25映射）中的完整iptables规则：
$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere
REJECT all -- loopback/8 anywhere reject-with icmp-port-unreachable
ACCEPT icmp -- anywhere anywhere icmp any
FILTERS all -- anywhere anywhere
Chain FORWARD (policy DROP)
target prot opt source destination
DOCKER-USER all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-1 all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain DOCKER (3 references)
target prot opt source destination
ACCEPT tcp -- anywhere 172.19.0.4 tcp dpt:3000
ACCEPT tcp -- anywhere 172.17.0.3 tcp dpt:smtp
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target prot opt source destination
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-ISOLATION-STAGE-2 (3 references)
target prot opt source destination
DROP all -- anywhere anywhere
DROP all -- anywhere anywhere
DROP all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-USER (1 references)
target prot opt source destination
FILTERS all -- anywhere anywhere
Chain FILTERS (2 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:http
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:https
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:urd
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
感谢您在Twitter上与我联系。我之前没有注意到它的其他人，我实际上已经调查了这个问题，我想我知道发生了什么。在你的例子中：
docker run --rm -it -p 465:25 python:3.6 python3 -m http.server 25
如果你使用iptables-save查看完整的防火墙配置，你会看到一堆NAT规则。您可能会在*nat部分看到类似的内容：
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
... snip ...
-A DOCKER ! -i br-abbaabbaabba -p tcp -m tcp --dport 465 -j DNAT --to-destination 172.18.0.10:25
因此，此规则在PREROUTING阶段执行，并重写传入的数据包，看起来总是端口25而不是端口465.这发生在filter表INPUT链运行之前。
所以我想如果你允许流量到端口25，那么实际上你也可以访问端口465。显然，您不希望允许访问所有端口25，因为它包括主机的端口25。
由于Docker，你在这一点上所做的所有常用技巧都变得更加困难。
你可以下去显式优于隐式路由并拆分主机与docker规则：
*filter
:INPUT ACCEPT [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:FILTERS - [0:0]
:DOCKER-USER - [0:0]
-F INPUT
-F DOCKER-USER
-F FILTERS
-A INPUT -i lo -j ACCEPT
-A INPUT ! -i lo -s 127.0.0.0/8 -j REJECT
-A INPUT -p icmp --icmp-type any -j ACCEPT
# Rules for services running on the host:
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
# Rules for services running in containers:
-A DOCKER-USER -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT
# This says dport 25, but is actually 465. Yay for prerouting + NAT.
# Service on real host port 25 should still be inaccessible because DOCKER-USER
# is only accessible via `FORWARD` and not `INPUT`...
-A DOCKER-USER -i eth0 -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT
-A DOCKER-USER -j REJECT --reject-with icmp-host-prohibited
COMMIT
您仍然不满意您允许到25号港口的交通。
我相信现在Docker没有在*raw或*mangle中放置任何东西，所以可以安全地在那里添加你自己的规则。显然这些表有局限性（原始是在连接跟踪之前，mangle仅用于标记连接）所以这也不是很好。
最后，我能想到的另一件事conntrack iptables模块可能有--ctorigdstport的答案，但我自己从未尝试过。看看this你可以尝试：
iptables -A FILTERS -p tcp --dport 25 -m conntrack --ctstate NEW --ctorigdstport 465 -j ACCEPT
看一下有点难看，但要明确发生了什么。如果您尝试这个并且它的工作让我知道，我将看到写它/更新该博客文章。