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尝试在 strongswan IPsec 隧道 docker 容器上转发 SMTP 端口？

tag-icon • tag-icon iptables port-forwarding ipsec
尝试在 strongswan IPsec 隧道 docker 容器上转发 SMTP 端口？

我已经在 docker 容器中成功设置了 vpn 隧道strongswan，并且想要使用该隧道连接将特定端口（如 SMTP）转发到隧道另一端的主机（就我而言）host 10.0.0.10。

目标是能够通过strongswan-container像这样连接到中间的服务直接在我的应用程序中使用 SMTP

(smtp-host)-[IPSec-tunnel]-(strongswan-container [exposes port 25 and forwards everything to tunneled smtp-host])-[some-docker-network]-(my-mail-sending-app-container [calls strongswan-container:25 for smtp])

在阅读了一些关于此内容的文档后，我尝试了这些iptables命令strongswan-container，但没有成功：

iptables -t nat -A PREROUTING  -p tcp --dport 25 -j DNAT --to-destination 10.0.0.10:25
iptables -t nat -A POSTROUTING -p tcp -d 10.0.0.10 --dport 25 -j MASQUERADE

我my-mail-sending-app-container尝试跑步

telnet strongswan-container 25

但它只会等待响应直到超时。

我的命令出了什么问题iptables？

iptables-savestrongswan 连接隧道后的输出：

root@14d43f1e2f55:/# iptables-save
# Generated by iptables-save v1.8.4 on Thu Jul 22 16:25:04 2021
*filter
:INPUT ACCEPT [1:112]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1:112]
-A INPUT -s 10.0.0.0/16 -d 192.168.112.2/32 -i eth0 -m policy --dir in --pol ipsec --reqid 1 --proto esp -j ACCEPT
-A OUTPUT -s 192.168.112.2/32 -d 10.0.0.0/16 -o eth0 -m policy --dir out --pol ipsec --reqid 1 --proto esp -j ACCEPT
COMMIT
# Completed on Thu Jul 22 16:25:04 2021
# Generated by iptables-save v1.8.4 on Thu Jul 22 16:25:04 2021
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [2:1600]
:POSTROUTING ACCEPT [2:1600]
:DOCKER_OUTPUT - [0:0]
:DOCKER_POSTROUTING - [0:0]
-A OUTPUT -d 127.0.0.11/32 -j DOCKER_OUTPUT
-A POSTROUTING -d 127.0.0.11/32 -j DOCKER_POSTROUTING
-A DOCKER_OUTPUT -d 127.0.0.11/32 -p tcp -m tcp --dport 53 -j DNAT --to-destination 127.0.0.11:46701
-A DOCKER_OUTPUT -d 127.0.0.11/32 -p udp -m udp --dport 53 -j DNAT --to-destination 127.0.0.11:58024
-A DOCKER_POSTROUTING -s 127.0.0.11/32 -p tcp -m tcp --sport 46701 -j SNAT --to-source :53
-A DOCKER_POSTROUTING -s 127.0.0.11/32 -p udp -m udp --sport 58024 -j SNAT --to-source :53
COMMIT
# Completed on Thu Jul 22 16:25:04 2021

我的ipsec.conf：

config setup
     strictcrlpolicy=no
     uniqueids=no

# left is local by default, left and right otherwise dynamically detected
conn %default

conn "ezvpn"
    keyexchange=ikev2
    aggressive=yes
    ike=(some-ciphers)     # Phase1 parameters
    esp=(some-ciphers)              # Phase2 parameters
    left=192.168.112.2         # local IP used to connect to IOS
    leftid=12.123.123.1                 # IKEID (group name) used for IOS
    leftfirewall=yes
    leftauth=psk
    rightauth=psk
    fragmentation=yes
    right=12.123.123.2        #gateway (IOS) IP
    rightsubnet=10.0.0.0/16
    rightfirewall=yes
    auto=route
    type=tunnel
    ikelifetime=180m
    keylife=60m

答案1

我通过安装traefik到我的strongswan容器中然后使用TCP routing功能在traefik内部公开隧道端口来解决这个问题。

Dockerfile（我完全清楚，这alpine也可以通过以下方式实现）：

FROM ubuntu


RUN apt update && apt-get install -yf wget iputils-ping telnet strongswan iptables \
    && ln -sf /conf/ipsec.conf /etc/ipsec.conf \
    && ln -sf /conf/ipsec.secrets /etc/ipsec.secrets \
    && echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf \
    && wget -O /traefik.tar.gz https://github.com/traefik/traefik/releases/download/v2.4.12/traefik_v2.4.12_linux_amd64.tar.gz \
    && tar -zxvf /traefik.tar.gz \
    && ln -s /traefik /usr/bin/traefik


COPY docker-entrypoint.sh /entrypoint.sh
COPY /strongswan /conf
COPY /traefik-conf /traefik-conf

CMD ["/entrypoint.sh"]

我的entrypoint.sh：

#!/bin/sh -e

{
    # wait to make sure ipsec is started when upping the tunnel
    sleep 2
    ipsec up ezvpn
    traefik --configfile /traefik-conf/traefik.yml
} &

exec ipsec start --nofork "$@"

traefik-conf/traefik.yml：

# https://doc.traefik.io/traefik/routing/entrypoints/
entryPoints:
  smtp:
    address: ":1025" # the port that listens within the docker network

accessLog: {}

providers:
  file:
    directory: /traefik-conf/dynamic/
    # I use dynamic configurations for local development
    watch: true

api:
  dashboard: true
  insecure: true

/traefik-conf/dynamic/dynamic.yml：

tcp:
  # https://doc.traefik.io/traefik/routing/routers/#rule_1
  routers:
    smtp-router:
      rule: "HostSNI(`*`)"
      entryPoints:
        - smtp
      service: smtp-service

  # https://doc.traefik.io/traefik/routing/routers/#services
  services:
    smtp-service:
      loadBalancer:
        servers:
          - address: 10.0.0.1:25 # replace with your target IP & service port

看这里以查看完整示例。

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