2

我刚刚配置了 Strongswan 并且可以在 AWS EC2 实例上成功启动 VPN 隧道，但是我遇到了流量问题，因为我们需要对我的 EC2 实例的私有 IP 地址进行 NAT，所以通过 VPN 的所有流量都来自一个特定的IP。

但目前，如果我 ping [DESTINATION_IP] 地址，我的流量仍然来自我的私有 IP。我在 iptables 中尝试了几个 PREROUTING 和 POSTROUTING 规则，但似乎没有任何效果。谁能解释可能是什么问题？

当前的设置

在 AWS 源/目标检查中禁用。

strongswan statusall

Listening IP addresses:
  [PRIVATE_IP]
Connections:
          vpn:  %any...[VPN_FIREWALL_IP]  IKEv2, dpddelay=10s
          vpn:   local:  [[ELASTIC_PUBLIC_IP]] uses pre-shared key authentication
          vpn:   remote: [[VPN_FIREWALL_IP]] uses pre-shared key authentication
          vpn:   child:  0.0.0.0/0 === [DESTINATION_IP]/32 TUNNEL, dpdaction=restart
Security Associations (1 up, 0 connecting):
          vpn[1]: ESTABLISHED 5 seconds ago, [PRIVATE_IP][[ELASTIC_PUBLIC_IP]]...[VPN_FIREWALL_IP][[VPN_FIREWALL_IP]]
          vpn[1]: IKEv2 SPIs: 6055db442ef8607c_i* 3d2ec0bb945e9a2c_r, pre-shared key reauthentication in 7 hours
          vpn[1]: IKE proposal: AES_CBC_128/HMAC_SHA2_256_128/PRF_HMAC_SHA1/MODP_2048
          vpn{1}:  INSTALLED, TUNNEL, reqid 1, ESP in UDP SPIs: ca9d2ca0_i df70a539_o
          vpn{1}:  AES_CBC_128/HMAC_SHA1_96, 0 bytes_i, 0 bytes_o, rekeying in 46 minutes
          vpn{1}:   [NAT_SOURCE_IP]/31 === [DESTINATION_IP]/32

ipsec.conf

config setup
    charondebug="all"
    uniqueids=no

conn %default
    ikelifetime=28800s
    keyexchange=ikev2
    keylife=3600s
    keyingtries=%forever
    mobike=no

conn vpn
    authby=psk
    auto=start
    dpddelay=10s
    dpdtimeout=30s
    dpdaction=restart
    ike=aes128-sha256-prfsha1-modp2048!
    esp=aes128-sha256-modp2048,aes128-sha1-modp2048!
    left=%defaultroute
    leftid=[ELASTIC_PUBLIC_IP]
    leftsubnet=0.0.0.0/0
    leftfirewall=yes
    rightsubnet=[DESTINATION_IP]/32
    right=[VPN_FIREWALL_IP]
    rightid=[VPN_FIREWALL_IP]
    type=tunnel
    mark=100

iptables-保存

*nat
:PREROUTING ACCEPT [9728:543855]
:INPUT ACCEPT [7882:388791]
:OUTPUT ACCEPT [20219:1527154]
:POSTROUTING ACCEPT [20725:1569658]
COMMIT
*filter
:INPUT ACCEPT [142:30437]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [188:34735]
-A FORWARD -s [DESTINATION_IP]/32 -d [NAT_SOURCE_IP]/31 -i eth0 -m policy --dir in --pol ipsec --reqid 1 --proto esp -j ACCEPT
-A FORWARD -s [NAT_SOURCE_IP]/31 -d [DESTINATION_IP]/32 -o eth0 -m policy --dir out --pol ipsec --reqid 1 --proto esp -j ACCEPT
COMMIT
4

1 回答 1

1

如果我正确理解您的问题，您是在询问如何使用 Strongswan 在 EC2 实例上设置源 NAT。我运行相同的设置，就我而言，遵循 [1] 中的 iptables 规则提供了请求的功能：

iptables -t nat -A POSTROUTING -s <NAT_SOURCE_IP>/24 -o eth0 -m policy --dir out --pol ipsec -j ACCEPT
iptables -t nat -A POSTROUTING -s <NAT_SOURCE_IP>/24 -o eth0 -j MASQUERADE

[1] https://wiki.strongswan.org/projects/strongswan/wiki/ForwardingAndSplitTunneling

于 2020-10-26T19:19:35.280 回答