我只能使用 IPv6 而不是 IPv4 連接到 OpenVPN 伺服器

我在 Synology Router 上設置了 OpenVPN 伺服器，但無法讓 IPv4 和 IPv6 連接正常工作。最初，我在弄清楚這一點時非常頭疼，但我已將其縮小到這一點：我可以通過它的 IPv6 地址成功連接到我的 OpenVPN 伺服器，但每次僅通過 IPv4 地址連接都會失敗。

我正在通過使用 DDNS 設置的域名進行連接。如果我手動將記錄設置為僅 IPv4 地址，它當然會失敗。一旦我更新 IPv6 記錄，它就會正常工作。

我已經在幾個不同的客戶端和網路上對此進行了測試，以確保它不是我的客戶端所在的網路。

這是我的伺服器配置： 伺服器配置

和客戶端配置文件：

dev tun
tls-client

remote my.domain.com 1194

redirect-gateway def1


pull

proto udp

script-security 2


reneg-sec 0

auth SHA1

cipher AES-128-CBC

auth-user-pass


key-direction 1

comp-lzo
explicit-exit-notify
<ca>

-----BEGIN CERTIFICATE-----

-----END CERTIFICATE-----
</ca>

<tls-auth>

-----BEGIN OpenVPN Static key V1-----

-----END OpenVPN Static key V1-----
</tls-auth>

這是客戶端連接日誌文件，已針對個人資訊進行了編輯：

5/20/2020, 1:03:10 AM OpenVPN core 3.git::15c71c44 win x86_64 64-bit PT_PROXY built on Feb 19 2020 17:36:01
⏎5/20/2020, 1:03:10 AM Frame=512/2048/512 mssfix-ctrl=1250
⏎5/20/2020, 1:03:10 AM UNUSED OPTIONS
1 [tls-client] 
4 [pull] 
6 [script-security] [2] 
13 [explicit-exit-notify] 
⏎5/20/2020, 1:03:10 AM EVENT: RESOLVE 
⏎5/20/2020, 1:03:10 AM EVENT: WAIT 
⏎5/20/2020, 1:03:10 AM Contacting 104.232.115.21:1194 via UDP
⏎5/20/2020, 1:03:10 AM Connecting to [my.domain.com]:1194 (x.x.x.x) via UDPv4
⏎5/20/2020, 1:03:20 AM Server poll timeout, trying next remote entry...
⏎5/20/2020, 1:03:20 AM EVENT: RECONNECTING
⏎5/20/2020, 1:03:20 AM EVENT: RESOLVE
⏎5/20/2020, 1:03:20 AM Contacting x.x.x.x:1194 via UDP
⏎5/20/2020, 1:03:20 AM Connecting to [my.domain.com]:1194 (x.x.x.x) via UDPv4
⏎5/20/2020, 1:03:20 AM EVENT: WAIT 
⏎5/20/2020, 1:03:30 AM Server poll timeout, trying next remote entry...

5 次嘗試失敗，直到超時：

⏎5/20/2020, 1:04:10 AM EVENT: CONNECTION_TIMEOUT
⏎5/20/2020, 1:04:10 AM EVENT: DISCONNECTED

現在嘗試 IPv6 地址

⏎5/20/2020, 1:04:46 AM OpenVPN core 3.git::15c71c44 win x86_64 64-bit PT_PROXY built on Feb 19 2020 17:36:01
⏎5/20/2020, 1:04:46 AM Frame=512/2048/512 mssfix-ctrl=1250
⏎5/20/2020, 1:04:46 AM UNUSED OPTIONS
1 [tls-client] 
4 [pull] 
6 [script-security] [2] 
13 [explicit-exit-notify] 
⏎5/20/2020, 1:04:46 AM EVENT: RESOLVE
⏎5/20/2020, 1:04:46 AM EVENT: WAIT
⏎5/20/2020, 1:04:46 AM Contacting x.x.x.x:1194 via UDP
⏎5/20/2020, 1:04:46 AM Connecting to [my.domain.com]:1194 (x.x.x.x) via UDPv4
⏎5/20/2020, 1:04:56 AM Server poll timeout, trying next remote entry...
⏎5/20/2020, 1:04:56 AM EVENT: RECONNECTING
⏎5/20/2020, 1:04:56 AM EVENT: RESOLVE
⏎5/20/2020, 1:04:56 AM EVENT: WAIT
⏎5/20/2020, 1:04:56 AM Contacting 104.232.115.21:1194 via UDP
⏎5/20/2020, 1:04:56 AM Connecting to [my.domain.com]:1194 (x.x.x.x) via UDPv4
⏎5/20/2020, 1:05:06 AM Server poll timeout, trying next remote entry...
⏎5/20/2020, 1:05:06 AM EVENT: RECONNECTING
⏎5/20/2020, 1:05:06 AM EVENT: RESOLVE
⏎5/20/2020, 1:05:06 AM EVENT: WAIT
⏎5/20/2020, 1:05:06 AM Contacting [xxxx::xxxx]:1194 via UDP
⏎5/20/2020, 1:05:06 AM Connecting to [my.domain.com]:1194 (xxxx::xxxx) via UDPv6
⏎5/20/2020, 1:05:06 AM EVENT: CONNECTING
⏎5/20/2020, 1:05:06 AM Tunnel Options:V4,dev-type tun,link-mtu 1558,tun-mtu 1500,proto UDPv4,comp-lzo,keydir 1,cipher AES-128-CBC,auth SHA1,keysize 128,tls-auth,key-method 2,tls-client
⏎5/20/2020, 1:05:06 AM Creds: Username/Password
⏎5/20/2020, 1:05:06 AM Peer Info:
IV_GUI_VER=OCmacOS_3.1.2-572
IV_VER=3.git::15c71c44
IV_PLAT=win
IV_NCP=2
IV_TCPNL=1
IV_PROTO=2
IV_LZO_STUB=1
IV_COMP_STUB=1
IV_COMP_STUBv2=1

⏎5/20/2020, 1:05:06 AM VERIFY OK : depth=1
Certificate Information

⏎5/20/2020, 1:05:06 AM VERIFY OK : depth=0
Certificate Information

⏎5/20/2020, 1:05:08 AM SSL Handshake: TLSv1.2/TLS-DHE-RSA-WITH-AES-256-GCM-SHA384
⏎5/20/2020, 1:05:08 AM Session is ACTIVE
⏎5/20/2020, 1:05:08 AM Sending PUSH_REQUEST to server...
⏎5/20/2020, 1:05:08 AM EVENT: GET_CONFIG 
⏎5/20/2020, 1:05:09 AM EVENT: DISCONNECTED

如您所見，使用 IPv6 地址時，它可以正常連接。但是當嘗試連接 IPv4 地址時，它每次都會失敗。這與我的 ISP 阻止某些 UDP 數據包有關嗎？我很好奇為什麼它只適用於 IPv6。

只花了幾個小時的故障排除，但我想通了，現在看起來很明顯，我不想承認。

在這一切開始時，我從 Synology 閱讀了一些需要在路由器上設置埠轉發規則的錯誤文件。但是他們忽略了提到如果您在路由器本身上使用 VPN 伺服器，您不應該這樣做！

我一起刪除了埠轉發規則，仔細檢查了我的防火牆規則並讓它正常工作。

引用自：https://serverfault.com/questions/1017896