試圖在 strongswan IPsec 隧道 docker 容器上轉發 SMTP 埠？

我已經在 docker 容器中成功設置了一個 vpn 隧道，strongswan並希望使用該隧道連接將特定埠（如 SMTP）轉發到隧道另一側的主機，在我的情況下host 10.0.0.10。

目標是能夠通過strongswan-container像這樣連接到中間的服務直接在我的應用程序中使用 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])

在閱讀了一些關於此的文件後，我嘗試了這些iptables命令strongswan-container但沒有成功：

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

在my-mail-sending-app-container我嘗試執行

telnet strongswan-container 25

但它只會等待響應直到超時。

我的iptables命令有什麼問題？

iptables-savestrongswan 連接隧道後的輸出：

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

我通過安裝traefik到我的strongswan容器中然後使用在內部公開隧道埠的TCP routing功能來解決它。traefik

Dockerfile（我完全知道這也可以使用來實現alpine）：

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

有關完整範例，請參見此處。

引用自：https://serverfault.com/questions/1070343