如何让 Docker 容器看到真实用户 IP？
How to make Docker container see real user IP?
问题
在 nginx-proxy Docker 容器内（更多信息见下文），我总是看到每个连接都有相同的 IP 地址：172.18.0.1（这是 nginx-proxy 网络网关).例如：
nginx.1 | www.my-site.tld 172.18.0.1 - - [28/Nov/2017:17:22:21 +0000] "GET /some/path HTTP/2.0" 200 46576 "https://www.my-site.tld/some/path" "Mozilla/5.0 (Linux; Android 4.4.2; PSP5507DUO Build/KVT49L) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 YaBrowser/17.10.0.446.00 Mobile Safari/537.36"
无论我从外部网络、本地机器甚至服务器（主机）本身发出请求，IP 地址始终是 172.18.0.1.
我需要的是看到真实的客户端IP。
尝试修复
我在谷歌上搜索了很多，并尝试了不同的解决方案，但 none 对我有用。我尝试了以下方法：
- 禁用 firewalld（当然，在那种情况下根本不起作用，
iptables 是空的);
- 使用
--userland-proxy=false（运气不好）；
- 使用
--net=host（根本不是解决方案，也不起作用）。
相关链接：
那么，有什么想法吗？似乎是 iptables 路由问题或内部 Docker 错误。无论如何，它肯定与Docker有关，因为以下显示正确的远程用户IP：
[root@server]# nc -lv 12345
[user@remote-client]$ nc -vz MY.IP.ADDRESS.HERE 12345
很奇怪！
现在我将提供有关系统的完整信息，请耐心等待。 :)
基本
我安装了 Centos 7.4 和 Docker:
# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core)
# uname -r
3.10.0-693.5.2.el7.x86_64
# docker version
Client:
Version: 17.09.0-ce
API version: 1.32
Go version: go1.8.3
Git commit: afdb6d4
Built: Tue Sep 26 22:41:23 2017
OS/Arch: linux/amd64
Server:
Version: 17.09.0-ce
API version: 1.32 (minimum version 1.12)
Go version: go1.8.3
Git commit: afdb6d4
Built: Tue Sep 26 22:42:49 2017
OS/Arch: linux/amd64
Experimental: false
firewalld用作防火墙。
网络配置
接口
共有三个物理接口：
# ifconfig | grep -A 7 enp
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::1ad6:c7ff:fe00:fc98 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:00:fc:98 txqueuelen 1000 (Ethernet)
RX packets 11530516 bytes 2220554890 (2.0 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 24237462 bytes 31702254967 (29.5 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::1ad6:c7ff:fe06:ef36 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:06:ef:36 txqueuelen 1000 (Ethernet)
RX packets 948513 bytes 143294797 (136.6 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2371584 bytes 3207775040 (2.9 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 31.172.141.111 netmask 255.255.255.128 broadcast MY.EXTERNAL.IP.HERE
inet6 fe80::127b:44ff:fe46:c2d1 prefixlen 64 scopeid 0x20<link>
ether 10:7b:44:46:c2:d1 txqueuelen 1000 (Ethernet)
RX packets 46772225 bytes 57416420859 (53.4 GiB)
RX errors 0 dropped 1 overruns 0 frame 0
TX packets 28814037 bytes 10943786995 (10.1 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
和一个虚拟网桥（enp1s0 和 enp2s0）：
# ifconfig | grep -A 7 virbr
virbr0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 fe80::1ad6:c7ff:fe00:fc98 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:00:fc:98 txqueuelen 1000 (Ethernet)
RX packets 11542053 bytes 2042945874 (1.9 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 26586017 bytes 34919742970 (32.5 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
防火墙区域
enp3s0接口连接到互联网(--zone=public)，virbr0连接到内部本地网络(--zone=internal)。
转发和伪装
IPv4 转发已启用：
# cat /proc/sys/net/ipv4/ip_forward
1
并在 public 区域上伪装配置了 firewalld:
# firewall-cmd --zone=public --list-all
success
Docker配置
Docker 有默认配置。
网络
我只创建了一个网络：
# docker network create -d bridge nginx-proxy
配置如下：
# docker network inspect nginx-proxy
[
{
"Name": "nginx-proxy",
"Id": "192821446c9a5891fd1a7e240533cefb81ba0548033acb605eea805abec83505",
"Created": "2017-11-24T14:25:10.687199435+02:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet": "172.18.0.0/16",
"Gateway": "172.18.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"1c563c33a45c9feabee4cb5ec3194464c66bfad1e233dedb797e269649067159": {
"Name": "nginxproxy_nginx-proxy_1",
"EndpointID": "683ceaced8eb416b485775734ca6828e9eced5ea6e3c7a76960c4eb807b521d9",
"MacAddress": "02:42:ac:12:00:02",
"IPv4Address": "172.18.0.2/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
}
]
图像和容器
我正在使用 jwilder/nginx-proxy 图片。这是我的 docker-compose.yml:
version: '3'
services:
nginx-proxy:
image: jwilder/nginx-proxy:alpine
labels:
- 'com.github.jrcs.letsencrypt_nginx_proxy_companion.nginx_proxy=true'
volumes:
- /var/run/docker.sock:/tmp/docker.sock:ro
ports:
- '80:80'
- '443:443'
networks:
nginx-proxy:
networks:
nginx-proxy:
depends_on:
- nginx-proxy
networks:
nginx-proxy:
external:
name: nginx-proxy
如您所见，nginx-proxy 容器正在所有接口上侦听端口 80 和 443。
# docker ps | grep nginx-proxy
1c563c33a45c jwilder/nginx-proxy:alpine "/app/docker-entry..." 8 hours ago Up 8 hours 0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp nginxproxy_nginx-proxy_1
iptables
容器相关规则
这里是与容器相关的 iptables 规则：
# iptables-save | grep -e br-192821446c9a -e 172.18.0 -e '\*'
*mangle
*security
*raw
*filter
-A FORWARD -o br-192821446c9a -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-192821446c9a -j DOCKER
-A FORWARD -i br-192821446c9a ! -o br-192821446c9a -j ACCEPT
-A FORWARD -i br-192821446c9a -o br-192821446c9a -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 80 -j ACCEPT
*nat
-A POSTROUTING -s 172.18.0.0/16 ! -o br-192821446c9a -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A DOCKER -i br-192821446c9a -j RETURN
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.18.0.2:443
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.18.0.2:80
完整的 iptables 规则列表
这里是 iptables-save 的完整输出：
# iptables-save
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*mangle
:PREROUTING ACCEPT [9063259:7480026035]
:INPUT ACCEPT [250719:30179859]
:FORWARD ACCEPT [8795875:7445096680]
:OUTPUT ACCEPT [1078071:1430559812]
:POSTROUTING ACCEPT [9842972:8867742437]
:FORWARD_direct - [0:0]
:INPUT_direct - [0:0]
:OUTPUT_direct - [0:0]
:POSTROUTING_direct - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A INPUT -j INPUT_direct
-A FORWARD -j FORWARD_direct
-A OUTPUT -j OUTPUT_direct
-A POSTROUTING -j POSTROUTING_direct
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*security
:INPUT ACCEPT [207361:25027156]
:FORWARD ACCEPT [8764800:7437165960]
:OUTPUT ACCEPT [1078077:1430561824]
:FORWARD_direct - [0:0]
:INPUT_direct - [0:0]
:OUTPUT_direct - [0:0]
-A INPUT -j INPUT_direct
-A FORWARD -j FORWARD_direct
-A OUTPUT -j OUTPUT_direct
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*raw
:PREROUTING ACCEPT [9063267:7480026451]
:OUTPUT ACCEPT [1078080:1430562828]
:OUTPUT_direct - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A OUTPUT -j OUTPUT_direct
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1078082:1430564354]
:DOCKER - [0:0]
:DOCKER-ISOLATION - [0:0]
:FORWARD_IN_ZONES - [0:0]
:FORWARD_IN_ZONES_SOURCE - [0:0]
:FORWARD_OUT_ZONES - [0:0]
:FORWARD_OUT_ZONES_SOURCE - [0:0]
:FORWARD_direct - [0:0]
:FWDI_internal - [0:0]
:FWDI_internal_allow - [0:0]
:FWDI_internal_deny - [0:0]
:FWDI_internal_log - [0:0]
:FWDI_public - [0:0]
:FWDI_public_allow - [0:0]
:FWDI_public_deny - [0:0]
:FWDI_public_log - [0:0]
:FWDO_internal - [0:0]
:FWDO_internal_allow - [0:0]
:FWDO_internal_deny - [0:0]
:FWDO_internal_log - [0:0]
:FWDO_public - [0:0]
:FWDO_public_allow - [0:0]
:FWDO_public_deny - [0:0]
:FWDO_public_log - [0:0]
:INPUT_ZONES - [0:0]
:INPUT_ZONES_SOURCE - [0:0]
:INPUT_direct - [0:0]
:IN_internal - [0:0]
:IN_internal_allow - [0:0]
:IN_internal_deny - [0:0]
:IN_internal_log - [0:0]
:IN_public - [0:0]
:IN_public_allow - [0:0]
:IN_public_deny - [0:0]
:IN_public_log - [0:0]
:OUTPUT_direct - [0:0]
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -j INPUT_direct
-A INPUT -j INPUT_ZONES_SOURCE
-A INPUT -j INPUT_ZONES
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j DOCKER-ISOLATION
-A FORWARD -o br-828c38e3582b -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-828c38e3582b -j DOCKER
-A FORWARD -i br-828c38e3582b ! -o br-828c38e3582b -j ACCEPT
-A FORWARD -i br-828c38e3582b -o br-828c38e3582b -j ACCEPT
-A FORWARD -o br-7cbbdaf3d8fe -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-7cbbdaf3d8fe -j DOCKER
-A FORWARD -i br-7cbbdaf3d8fe ! -o br-7cbbdaf3d8fe -j ACCEPT
-A FORWARD -i br-7cbbdaf3d8fe -o br-7cbbdaf3d8fe -j ACCEPT
-A FORWARD -o br-92f8d769de0b -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-92f8d769de0b -j DOCKER
-A FORWARD -i br-92f8d769de0b ! -o br-92f8d769de0b -j ACCEPT
-A FORWARD -i br-92f8d769de0b -o br-92f8d769de0b -j ACCEPT
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -o br-6a38b645b1c7 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-6a38b645b1c7 -j DOCKER
-A FORWARD -i br-6a38b645b1c7 ! -o br-6a38b645b1c7 -j ACCEPT
-A FORWARD -i br-6a38b645b1c7 -o br-6a38b645b1c7 -j ACCEPT
-A FORWARD -o br-2d90be830c58 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-2d90be830c58 -j DOCKER
-A FORWARD -i br-2d90be830c58 ! -o br-2d90be830c58 -j ACCEPT
-A FORWARD -i br-2d90be830c58 -o br-2d90be830c58 -j ACCEPT
-A FORWARD -o br-192821446c9a -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-192821446c9a -j DOCKER
-A FORWARD -i br-192821446c9a ! -o br-192821446c9a -j ACCEPT
-A FORWARD -i br-192821446c9a -o br-192821446c9a -j ACCEPT
-A FORWARD -o br-b61364bf1724 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-b61364bf1724 -j DOCKER
-A FORWARD -i br-b61364bf1724 ! -o br-b61364bf1724 -j ACCEPT
-A FORWARD -i br-b61364bf1724 -o br-b61364bf1724 -j ACCEPT
-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i lo -j ACCEPT
-A FORWARD -j FORWARD_direct
-A FORWARD -j FORWARD_IN_ZONES_SOURCE
-A FORWARD -j FORWARD_IN_ZONES
-A FORWARD -j FORWARD_OUT_ZONES_SOURCE
-A FORWARD -j FORWARD_OUT_ZONES
-A FORWARD -m conntrack --ctstate INVALID -j DROP
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
-A OUTPUT -j OUTPUT_direct
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 80 -j ACCEPT
-A DOCKER -d 172.20.0.2/32 ! -i br-2d90be830c58 -o br-2d90be830c58 -p tcp -m tcp --dport 1194 -j ACCEPT
-A DOCKER-ISOLATION -j RETURN
-A FORWARD_IN_ZONES -i enp3s0 -g FWDI_public
-A FORWARD_IN_ZONES -i virbr0 -g FWDI_internal
-A FORWARD_IN_ZONES -g FWDI_public
-A FORWARD_OUT_ZONES -o enp3s0 -g FWDO_public
-A FORWARD_OUT_ZONES -o virbr0 -g FWDO_internal
-A FORWARD_OUT_ZONES -g FWDO_public
-A FWDI_internal -j FWDI_internal_log
-A FWDI_internal -j FWDI_internal_deny
-A FWDI_internal -j FWDI_internal_allow
-A FWDI_internal -p icmp -j ACCEPT
-A FWDI_public -j FWDI_public_log
-A FWDI_public -j FWDI_public_deny
-A FWDI_public -j FWDI_public_allow
-A FWDI_public -p icmp -j ACCEPT
-A FWDO_internal -j FWDO_internal_log
-A FWDO_internal -j FWDO_internal_deny
-A FWDO_internal -j FWDO_internal_allow
-A FWDO_public -j FWDO_public_log
-A FWDO_public -j FWDO_public_deny
-A FWDO_public -j FWDO_public_allow
-A FWDO_public_allow -m conntrack --ctstate NEW -j ACCEPT
-A INPUT_ZONES -i enp3s0 -g IN_public
-A INPUT_ZONES -i virbr0 -g IN_internal
-A INPUT_ZONES -g IN_public
-A IN_internal -j IN_internal_log
-A IN_internal -j IN_internal_deny
-A IN_internal -j IN_internal_allow
-A IN_internal -p icmp -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -d 224.0.0.251/32 -p udp -m udp --dport 5353 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 137 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 138 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 2049 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 20048 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 20048 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 111 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 111 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 139 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 445 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 58846 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 8112 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 53 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 53 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public -j IN_public_log
-A IN_public -j IN_public_deny
-A IN_public -j IN_public_allow
-A IN_public -p icmp -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p udp -m udp --dport 67 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 443 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p udp -m udp --dport 1194 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 1195 -m conntrack --ctstate NEW -j ACCEPT
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*nat
:PREROUTING ACCEPT [118631:13941821]
:INPUT ACCEPT [6147:464301]
:OUTPUT ACCEPT [18836:1989867]
:POSTROUTING ACCEPT [2593:197858]
:DOCKER - [0:0]
:OUTPUT_direct - [0:0]
:POSTROUTING_ZONES - [0:0]
:POSTROUTING_ZONES_SOURCE - [0:0]
:POSTROUTING_direct - [0:0]
:POST_internal - [0:0]
:POST_internal_allow - [0:0]
:POST_internal_deny - [0:0]
:POST_internal_log - [0:0]
:POST_public - [0:0]
:POST_public_allow - [0:0]
:POST_public_deny - [0:0]
:POST_public_log - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT -j OUTPUT_direct
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.101.0.0/24 ! -o br-828c38e3582b -j MASQUERADE
-A POSTROUTING -s 172.102.0.0/24 ! -o br-7cbbdaf3d8fe -j MASQUERADE
-A POSTROUTING -s 172.101.0.0/24 ! -o br-92f8d769de0b -j MASQUERADE
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.102.0.0/24 ! -o br-6a38b645b1c7 -j MASQUERADE
-A POSTROUTING -s 172.20.0.0/16 ! -o br-2d90be830c58 -j MASQUERADE
-A POSTROUTING -s 172.18.0.0/16 ! -o br-192821446c9a -j MASQUERADE
-A POSTROUTING -s 172.19.0.0/16 ! -o br-b61364bf1724 -j MASQUERADE
-A POSTROUTING -j POSTROUTING_direct
-A POSTROUTING -j POSTROUTING_ZONES_SOURCE
-A POSTROUTING -j POSTROUTING_ZONES
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.20.0.2/32 -d 172.20.0.2/32 -p tcp -m tcp --dport 1194 -j MASQUERADE
-A DOCKER -i br-828c38e3582b -j RETURN
-A DOCKER -i br-7cbbdaf3d8fe -j RETURN
-A DOCKER -i br-92f8d769de0b -j RETURN
-A DOCKER -i docker0 -j RETURN
-A DOCKER -i br-6a38b645b1c7 -j RETURN
-A DOCKER -i br-2d90be830c58 -j RETURN
-A DOCKER -i br-192821446c9a -j RETURN
-A DOCKER -i br-b61364bf1724 -j RETURN
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.18.0.2:443
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.18.0.2:80
-A DOCKER ! -i br-2d90be830c58 -p tcp -m tcp --dport 1195 -j DNAT --to-destination 172.20.0.2:1194
-A POSTROUTING_ZONES -o enp3s0 -g POST_public
-A POSTROUTING_ZONES -o virbr0 -g POST_internal
-A POSTROUTING_ZONES -g POST_public
-A POST_internal -j POST_internal_log
-A POST_internal -j POST_internal_deny
-A POST_internal -j POST_internal_allow
-A POST_public -j POST_public_log
-A POST_public -j POST_public_deny
-A POST_public -j POST_public_allow
-A POST_public_allow ! -o lo -j MASQUERADE
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
最后，回答我自己的问题。
经过一番研究，我发现是 IP 伪装导致 Docker 无法正确识别客户端地址。
原因
在我的例子中，firewalld 配置为与本地网络中的其他机器共享互联网连接。这是通过将外部接口 (enp3s0) 的区域设置为 public 和本地接口 (enp1s0、enp2s0) 的 internal 来实现的，并通过为外发包启用 IP 伪装。
就是这样。伪装也适用于从 public 网络到 docker 网络的包，就好像该包要去（另一个）外部接口一样。
解决方案
据我了解所有 iptables 和 Docker 的东西，有一个可以接受的解决方法：将 Docker 创建的所有虚拟网络接口添加到 internal 区域，所以伪装规则不适用于去往相应网络的包。例如：
# firewall-cmd --permanent --zone=internal --change-interface=br-192821446c9a
要使方案持久化，需要在/etc/sysconfig/network-scripts目录下创建相应的脚本。例如，对于br-192821446c9a接口，应该创建一个文件/etc/sysconfig/network-scripts/ifcfg-br-192821446c9a，内容如下：
DEVICE=br-192821446c9a
TYPE=Bridge
BOOTPROTO=none
IPADDR=172.18.0.1
PREFIX=16
DEFROUTE=yes
IPV4_DNS_PRIORITY=100
NAME=br-192821446c9a
ONBOOT=no
ZONE=internal
希望这个回答能节省一些人的时间。
问题
在 nginx-proxy Docker 容器内（更多信息见下文），我总是看到每个连接都有相同的 IP 地址：172.18.0.1（这是 nginx-proxy 网络网关).例如：
nginx.1 | www.my-site.tld 172.18.0.1 - - [28/Nov/2017:17:22:21 +0000] "GET /some/path HTTP/2.0" 200 46576 "https://www.my-site.tld/some/path" "Mozilla/5.0 (Linux; Android 4.4.2; PSP5507DUO Build/KVT49L) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 YaBrowser/17.10.0.446.00 Mobile Safari/537.36"
无论我从外部网络、本地机器甚至服务器（主机）本身发出请求，IP 地址始终是 172.18.0.1.
我需要的是看到真实的客户端IP。
尝试修复
我在谷歌上搜索了很多，并尝试了不同的解决方案，但 none 对我有用。我尝试了以下方法：
- 禁用 firewalld（当然，在那种情况下根本不起作用， iptables 是空的);
- 使用
--userland-proxy=false（运气不好）； - 使用
--net=host（根本不是解决方案，也不起作用）。
相关链接：
那么，有什么想法吗？似乎是 iptables 路由问题或内部 Docker 错误。无论如何，它肯定与Docker有关，因为以下显示正确的远程用户IP：
[root@server]# nc -lv 12345
[user@remote-client]$ nc -vz MY.IP.ADDRESS.HERE 12345
很奇怪！
现在我将提供有关系统的完整信息，请耐心等待。 :)
基本
我安装了 Centos 7.4 和 Docker:
# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core)
# uname -r
3.10.0-693.5.2.el7.x86_64
# docker version
Client:
Version: 17.09.0-ce
API version: 1.32
Go version: go1.8.3
Git commit: afdb6d4
Built: Tue Sep 26 22:41:23 2017
OS/Arch: linux/amd64
Server:
Version: 17.09.0-ce
API version: 1.32 (minimum version 1.12)
Go version: go1.8.3
Git commit: afdb6d4
Built: Tue Sep 26 22:42:49 2017
OS/Arch: linux/amd64
Experimental: false
firewalld用作防火墙。
网络配置
接口
共有三个物理接口：
# ifconfig | grep -A 7 enp
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::1ad6:c7ff:fe00:fc98 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:00:fc:98 txqueuelen 1000 (Ethernet)
RX packets 11530516 bytes 2220554890 (2.0 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 24237462 bytes 31702254967 (29.5 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::1ad6:c7ff:fe06:ef36 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:06:ef:36 txqueuelen 1000 (Ethernet)
RX packets 948513 bytes 143294797 (136.6 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2371584 bytes 3207775040 (2.9 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 31.172.141.111 netmask 255.255.255.128 broadcast MY.EXTERNAL.IP.HERE
inet6 fe80::127b:44ff:fe46:c2d1 prefixlen 64 scopeid 0x20<link>
ether 10:7b:44:46:c2:d1 txqueuelen 1000 (Ethernet)
RX packets 46772225 bytes 57416420859 (53.4 GiB)
RX errors 0 dropped 1 overruns 0 frame 0
TX packets 28814037 bytes 10943786995 (10.1 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
和一个虚拟网桥（enp1s0 和 enp2s0）：
# ifconfig | grep -A 7 virbr
virbr0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 fe80::1ad6:c7ff:fe00:fc98 prefixlen 64 scopeid 0x20<link>
ether 18:d6:c7:00:fc:98 txqueuelen 1000 (Ethernet)
RX packets 11542053 bytes 2042945874 (1.9 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 26586017 bytes 34919742970 (32.5 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
防火墙区域
enp3s0接口连接到互联网(--zone=public)，virbr0连接到内部本地网络(--zone=internal)。
转发和伪装
IPv4 转发已启用：
# cat /proc/sys/net/ipv4/ip_forward
1
并在 public 区域上伪装配置了 firewalld:
# firewall-cmd --zone=public --list-all
success
Docker配置
Docker 有默认配置。
网络
我只创建了一个网络：
# docker network create -d bridge nginx-proxy
配置如下：
# docker network inspect nginx-proxy
[
{
"Name": "nginx-proxy",
"Id": "192821446c9a5891fd1a7e240533cefb81ba0548033acb605eea805abec83505",
"Created": "2017-11-24T14:25:10.687199435+02:00",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet": "172.18.0.0/16",
"Gateway": "172.18.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {
"1c563c33a45c9feabee4cb5ec3194464c66bfad1e233dedb797e269649067159": {
"Name": "nginxproxy_nginx-proxy_1",
"EndpointID": "683ceaced8eb416b485775734ca6828e9eced5ea6e3c7a76960c4eb807b521d9",
"MacAddress": "02:42:ac:12:00:02",
"IPv4Address": "172.18.0.2/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
}
]
图像和容器
我正在使用 jwilder/nginx-proxy 图片。这是我的 docker-compose.yml:
version: '3'
services:
nginx-proxy:
image: jwilder/nginx-proxy:alpine
labels:
- 'com.github.jrcs.letsencrypt_nginx_proxy_companion.nginx_proxy=true'
volumes:
- /var/run/docker.sock:/tmp/docker.sock:ro
ports:
- '80:80'
- '443:443'
networks:
nginx-proxy:
networks:
nginx-proxy:
depends_on:
- nginx-proxy
networks:
nginx-proxy:
external:
name: nginx-proxy
如您所见，nginx-proxy 容器正在所有接口上侦听端口 80 和 443。
# docker ps | grep nginx-proxy
1c563c33a45c jwilder/nginx-proxy:alpine "/app/docker-entry..." 8 hours ago Up 8 hours 0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp nginxproxy_nginx-proxy_1
iptables
容器相关规则
这里是与容器相关的 iptables 规则：
# iptables-save | grep -e br-192821446c9a -e 172.18.0 -e '\*'
*mangle
*security
*raw
*filter
-A FORWARD -o br-192821446c9a -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-192821446c9a -j DOCKER
-A FORWARD -i br-192821446c9a ! -o br-192821446c9a -j ACCEPT
-A FORWARD -i br-192821446c9a -o br-192821446c9a -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 80 -j ACCEPT
*nat
-A POSTROUTING -s 172.18.0.0/16 ! -o br-192821446c9a -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A DOCKER -i br-192821446c9a -j RETURN
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.18.0.2:443
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.18.0.2:80
完整的 iptables 规则列表
这里是 iptables-save 的完整输出：
# iptables-save
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*mangle
:PREROUTING ACCEPT [9063259:7480026035]
:INPUT ACCEPT [250719:30179859]
:FORWARD ACCEPT [8795875:7445096680]
:OUTPUT ACCEPT [1078071:1430559812]
:POSTROUTING ACCEPT [9842972:8867742437]
:FORWARD_direct - [0:0]
:INPUT_direct - [0:0]
:OUTPUT_direct - [0:0]
:POSTROUTING_direct - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A INPUT -j INPUT_direct
-A FORWARD -j FORWARD_direct
-A OUTPUT -j OUTPUT_direct
-A POSTROUTING -j POSTROUTING_direct
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*security
:INPUT ACCEPT [207361:25027156]
:FORWARD ACCEPT [8764800:7437165960]
:OUTPUT ACCEPT [1078077:1430561824]
:FORWARD_direct - [0:0]
:INPUT_direct - [0:0]
:OUTPUT_direct - [0:0]
-A INPUT -j INPUT_direct
-A FORWARD -j FORWARD_direct
-A OUTPUT -j OUTPUT_direct
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*raw
:PREROUTING ACCEPT [9063267:7480026451]
:OUTPUT ACCEPT [1078080:1430562828]
:OUTPUT_direct - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A OUTPUT -j OUTPUT_direct
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1078082:1430564354]
:DOCKER - [0:0]
:DOCKER-ISOLATION - [0:0]
:FORWARD_IN_ZONES - [0:0]
:FORWARD_IN_ZONES_SOURCE - [0:0]
:FORWARD_OUT_ZONES - [0:0]
:FORWARD_OUT_ZONES_SOURCE - [0:0]
:FORWARD_direct - [0:0]
:FWDI_internal - [0:0]
:FWDI_internal_allow - [0:0]
:FWDI_internal_deny - [0:0]
:FWDI_internal_log - [0:0]
:FWDI_public - [0:0]
:FWDI_public_allow - [0:0]
:FWDI_public_deny - [0:0]
:FWDI_public_log - [0:0]
:FWDO_internal - [0:0]
:FWDO_internal_allow - [0:0]
:FWDO_internal_deny - [0:0]
:FWDO_internal_log - [0:0]
:FWDO_public - [0:0]
:FWDO_public_allow - [0:0]
:FWDO_public_deny - [0:0]
:FWDO_public_log - [0:0]
:INPUT_ZONES - [0:0]
:INPUT_ZONES_SOURCE - [0:0]
:INPUT_direct - [0:0]
:IN_internal - [0:0]
:IN_internal_allow - [0:0]
:IN_internal_deny - [0:0]
:IN_internal_log - [0:0]
:IN_public - [0:0]
:IN_public_allow - [0:0]
:IN_public_deny - [0:0]
:IN_public_log - [0:0]
:OUTPUT_direct - [0:0]
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -j INPUT_direct
-A INPUT -j INPUT_ZONES_SOURCE
-A INPUT -j INPUT_ZONES
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j DOCKER-ISOLATION
-A FORWARD -o br-828c38e3582b -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-828c38e3582b -j DOCKER
-A FORWARD -i br-828c38e3582b ! -o br-828c38e3582b -j ACCEPT
-A FORWARD -i br-828c38e3582b -o br-828c38e3582b -j ACCEPT
-A FORWARD -o br-7cbbdaf3d8fe -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-7cbbdaf3d8fe -j DOCKER
-A FORWARD -i br-7cbbdaf3d8fe ! -o br-7cbbdaf3d8fe -j ACCEPT
-A FORWARD -i br-7cbbdaf3d8fe -o br-7cbbdaf3d8fe -j ACCEPT
-A FORWARD -o br-92f8d769de0b -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-92f8d769de0b -j DOCKER
-A FORWARD -i br-92f8d769de0b ! -o br-92f8d769de0b -j ACCEPT
-A FORWARD -i br-92f8d769de0b -o br-92f8d769de0b -j ACCEPT
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -o br-6a38b645b1c7 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-6a38b645b1c7 -j DOCKER
-A FORWARD -i br-6a38b645b1c7 ! -o br-6a38b645b1c7 -j ACCEPT
-A FORWARD -i br-6a38b645b1c7 -o br-6a38b645b1c7 -j ACCEPT
-A FORWARD -o br-2d90be830c58 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-2d90be830c58 -j DOCKER
-A FORWARD -i br-2d90be830c58 ! -o br-2d90be830c58 -j ACCEPT
-A FORWARD -i br-2d90be830c58 -o br-2d90be830c58 -j ACCEPT
-A FORWARD -o br-192821446c9a -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-192821446c9a -j DOCKER
-A FORWARD -i br-192821446c9a ! -o br-192821446c9a -j ACCEPT
-A FORWARD -i br-192821446c9a -o br-192821446c9a -j ACCEPT
-A FORWARD -o br-b61364bf1724 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-b61364bf1724 -j DOCKER
-A FORWARD -i br-b61364bf1724 ! -o br-b61364bf1724 -j ACCEPT
-A FORWARD -i br-b61364bf1724 -o br-b61364bf1724 -j ACCEPT
-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i lo -j ACCEPT
-A FORWARD -j FORWARD_direct
-A FORWARD -j FORWARD_IN_ZONES_SOURCE
-A FORWARD -j FORWARD_IN_ZONES
-A FORWARD -j FORWARD_OUT_ZONES_SOURCE
-A FORWARD -j FORWARD_OUT_ZONES
-A FORWARD -m conntrack --ctstate INVALID -j DROP
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
-A OUTPUT -j OUTPUT_direct
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-192821446c9a -o br-192821446c9a -p tcp -m tcp --dport 80 -j ACCEPT
-A DOCKER -d 172.20.0.2/32 ! -i br-2d90be830c58 -o br-2d90be830c58 -p tcp -m tcp --dport 1194 -j ACCEPT
-A DOCKER-ISOLATION -j RETURN
-A FORWARD_IN_ZONES -i enp3s0 -g FWDI_public
-A FORWARD_IN_ZONES -i virbr0 -g FWDI_internal
-A FORWARD_IN_ZONES -g FWDI_public
-A FORWARD_OUT_ZONES -o enp3s0 -g FWDO_public
-A FORWARD_OUT_ZONES -o virbr0 -g FWDO_internal
-A FORWARD_OUT_ZONES -g FWDO_public
-A FWDI_internal -j FWDI_internal_log
-A FWDI_internal -j FWDI_internal_deny
-A FWDI_internal -j FWDI_internal_allow
-A FWDI_internal -p icmp -j ACCEPT
-A FWDI_public -j FWDI_public_log
-A FWDI_public -j FWDI_public_deny
-A FWDI_public -j FWDI_public_allow
-A FWDI_public -p icmp -j ACCEPT
-A FWDO_internal -j FWDO_internal_log
-A FWDO_internal -j FWDO_internal_deny
-A FWDO_internal -j FWDO_internal_allow
-A FWDO_public -j FWDO_public_log
-A FWDO_public -j FWDO_public_deny
-A FWDO_public -j FWDO_public_allow
-A FWDO_public_allow -m conntrack --ctstate NEW -j ACCEPT
-A INPUT_ZONES -i enp3s0 -g IN_public
-A INPUT_ZONES -i virbr0 -g IN_internal
-A INPUT_ZONES -g IN_public
-A IN_internal -j IN_internal_log
-A IN_internal -j IN_internal_deny
-A IN_internal -j IN_internal_allow
-A IN_internal -p icmp -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -d 224.0.0.251/32 -p udp -m udp --dport 5353 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 137 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 138 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 2049 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 20048 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 20048 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 111 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 111 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 139 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 445 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 58846 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 8112 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p tcp -m tcp --dport 53 -m conntrack --ctstate NEW -j ACCEPT
-A IN_internal_allow -p udp -m udp --dport 53 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public -j IN_public_log
-A IN_public -j IN_public_deny
-A IN_public -j IN_public_allow
-A IN_public -p icmp -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p udp -m udp --dport 67 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 443 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p udp -m udp --dport 1194 -m conntrack --ctstate NEW -j ACCEPT
-A IN_public_allow -p tcp -m tcp --dport 1195 -m conntrack --ctstate NEW -j ACCEPT
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
# Generated by iptables-save v1.4.21 on Tue Nov 28 19:16:31 2017
*nat
:PREROUTING ACCEPT [118631:13941821]
:INPUT ACCEPT [6147:464301]
:OUTPUT ACCEPT [18836:1989867]
:POSTROUTING ACCEPT [2593:197858]
:DOCKER - [0:0]
:OUTPUT_direct - [0:0]
:POSTROUTING_ZONES - [0:0]
:POSTROUTING_ZONES_SOURCE - [0:0]
:POSTROUTING_direct - [0:0]
:POST_internal - [0:0]
:POST_internal_allow - [0:0]
:POST_internal_deny - [0:0]
:POST_internal_log - [0:0]
:POST_public - [0:0]
:POST_public_allow - [0:0]
:POST_public_deny - [0:0]
:POST_public_log - [0:0]
:PREROUTING_ZONES - [0:0]
:PREROUTING_ZONES_SOURCE - [0:0]
:PREROUTING_direct - [0:0]
:PRE_internal - [0:0]
:PRE_internal_allow - [0:0]
:PRE_internal_deny - [0:0]
:PRE_internal_log - [0:0]
:PRE_public - [0:0]
:PRE_public_allow - [0:0]
:PRE_public_deny - [0:0]
:PRE_public_log - [0:0]
-A PREROUTING -j PREROUTING_direct
-A PREROUTING -j PREROUTING_ZONES_SOURCE
-A PREROUTING -j PREROUTING_ZONES
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT -j OUTPUT_direct
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.101.0.0/24 ! -o br-828c38e3582b -j MASQUERADE
-A POSTROUTING -s 172.102.0.0/24 ! -o br-7cbbdaf3d8fe -j MASQUERADE
-A POSTROUTING -s 172.101.0.0/24 ! -o br-92f8d769de0b -j MASQUERADE
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.102.0.0/24 ! -o br-6a38b645b1c7 -j MASQUERADE
-A POSTROUTING -s 172.20.0.0/16 ! -o br-2d90be830c58 -j MASQUERADE
-A POSTROUTING -s 172.18.0.0/16 ! -o br-192821446c9a -j MASQUERADE
-A POSTROUTING -s 172.19.0.0/16 ! -o br-b61364bf1724 -j MASQUERADE
-A POSTROUTING -j POSTROUTING_direct
-A POSTROUTING -j POSTROUTING_ZONES_SOURCE
-A POSTROUTING -j POSTROUTING_ZONES
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A POSTROUTING -s 172.20.0.2/32 -d 172.20.0.2/32 -p tcp -m tcp --dport 1194 -j MASQUERADE
-A DOCKER -i br-828c38e3582b -j RETURN
-A DOCKER -i br-7cbbdaf3d8fe -j RETURN
-A DOCKER -i br-92f8d769de0b -j RETURN
-A DOCKER -i docker0 -j RETURN
-A DOCKER -i br-6a38b645b1c7 -j RETURN
-A DOCKER -i br-2d90be830c58 -j RETURN
-A DOCKER -i br-192821446c9a -j RETURN
-A DOCKER -i br-b61364bf1724 -j RETURN
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.18.0.2:443
-A DOCKER ! -i br-192821446c9a -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.18.0.2:80
-A DOCKER ! -i br-2d90be830c58 -p tcp -m tcp --dport 1195 -j DNAT --to-destination 172.20.0.2:1194
-A POSTROUTING_ZONES -o enp3s0 -g POST_public
-A POSTROUTING_ZONES -o virbr0 -g POST_internal
-A POSTROUTING_ZONES -g POST_public
-A POST_internal -j POST_internal_log
-A POST_internal -j POST_internal_deny
-A POST_internal -j POST_internal_allow
-A POST_public -j POST_public_log
-A POST_public -j POST_public_deny
-A POST_public -j POST_public_allow
-A POST_public_allow ! -o lo -j MASQUERADE
-A PREROUTING_ZONES -i enp3s0 -g PRE_public
-A PREROUTING_ZONES -i virbr0 -g PRE_internal
-A PREROUTING_ZONES -g PRE_public
-A PRE_internal -j PRE_internal_log
-A PRE_internal -j PRE_internal_deny
-A PRE_internal -j PRE_internal_allow
-A PRE_public -j PRE_public_log
-A PRE_public -j PRE_public_deny
-A PRE_public -j PRE_public_allow
COMMIT
# Completed on Tue Nov 28 19:16:31 2017
最后，回答我自己的问题。
经过一番研究，我发现是 IP 伪装导致 Docker 无法正确识别客户端地址。
原因
在我的例子中，firewalld 配置为与本地网络中的其他机器共享互联网连接。这是通过将外部接口 (enp3s0) 的区域设置为 public 和本地接口 (enp1s0、enp2s0) 的 internal 来实现的，并通过为外发包启用 IP 伪装。
就是这样。伪装也适用于从 public 网络到 docker 网络的包，就好像该包要去（另一个）外部接口一样。
解决方案
据我了解所有 iptables 和 Docker 的东西，有一个可以接受的解决方法：将 Docker 创建的所有虚拟网络接口添加到 internal 区域，所以伪装规则不适用于去往相应网络的包。例如：
# firewall-cmd --permanent --zone=internal --change-interface=br-192821446c9a
要使方案持久化，需要在/etc/sysconfig/network-scripts目录下创建相应的脚本。例如，对于br-192821446c9a接口，应该创建一个文件/etc/sysconfig/network-scripts/ifcfg-br-192821446c9a，内容如下：
DEVICE=br-192821446c9a
TYPE=Bridge
BOOTPROTO=none
IPADDR=172.18.0.1
PREFIX=16
DEFROUTE=yes
IPV4_DNS_PRIORITY=100
NAME=br-192821446c9a
ONBOOT=no
ZONE=internal
希望这个回答能节省一些人的时间。